Merge remote-tracking branch 'origin/master' into patch-2

Analysis/include/Luau/BuiltinDefinitions.h

@@ -65,10 +65,7 @@ TypeId makeFunction( // Polymorphic
     bool checked = false
 );
 
-void attachMagicFunction(TypeId ty, MagicFunction fn);
-void attachDcrMagicFunction(TypeId ty, DcrMagicFunction fn);
-void attachDcrMagicRefinement(TypeId ty, DcrMagicRefinement fn);
-void attachDcrMagicFunctionTypeCheck(TypeId ty, DcrMagicFunctionTypeCheck fn);
+void attachMagicFunction(TypeId ty, std::shared_ptr<MagicFunction> fn);
 Property makeProperty(TypeId ty, std::optional<std::string> documentationSymbol = std::nullopt);
 void assignPropDocumentationSymbols(TableType::Props& props, const std::string& baseName);
 

Analysis/include/Luau/Clone.h

@@ -4,6 +4,7 @@
 #include <Luau/NotNull.h>
 #include "Luau/TypeArena.h"
 #include "Luau/Type.h"
+#include "Luau/Scope.h"
 
 #include <unordered_map>
 
@@ -26,13 +27,17 @@ struct CloneState
  * while `clone` will make a deep copy of the entire type and its every component.
  *
  * Be mindful about which behavior you actually _want_.
+ *
+ * Persistent types are not cloned as an optimization.
+ * If a type is cloned in order to mutate it, 'ignorePersistent' has to be set
  */
 
-TypePackId shallowClone(TypePackId tp, TypeArena& dest, CloneState& cloneState);
-TypeId shallowClone(TypeId typeId, TypeArena& dest, CloneState& cloneState);
+TypePackId shallowClone(TypePackId tp, TypeArena& dest, CloneState& cloneState, bool ignorePersistent = false);
+TypeId shallowClone(TypeId typeId, TypeArena& dest, CloneState& cloneState, bool ignorePersistent = false);
 
 TypePackId clone(TypePackId tp, TypeArena& dest, CloneState& cloneState);
 TypeId clone(TypeId tp, TypeArena& dest, CloneState& cloneState);
 TypeFun clone(const TypeFun& typeFun, TypeArena& dest, CloneState& cloneState);
+Binding clone(const Binding& binding, TypeArena& dest, CloneState& cloneState);
 
 } // namespace Luau

Analysis/include/Luau/ConstraintSolver.h

@@ -166,7 +166,7 @@ struct ConstraintSolver
      **/
     void finalizeTypeFunctions();
 
-    bool isDone();
+    bool isDone() const;
 
 private:
     /**
@@ -298,10 +298,10 @@ public:
     // FIXME: This use of a boolean for the return result is an appalling
     // interface.
     bool blockOnPendingTypes(TypeId target, NotNull<const Constraint> constraint);
-    bool blockOnPendingTypes(TypePackId target, NotNull<const Constraint> constraint);
+    bool blockOnPendingTypes(TypePackId targetPack, NotNull<const Constraint> constraint);
 
     void unblock(NotNull<const Constraint> progressed);
-    void unblock(TypeId progressed, Location location);
+    void unblock(TypeId ty, Location location);
     void unblock(TypePackId progressed, Location location);
     void unblock(const std::vector<TypeId>& types, Location location);
     void unblock(const std::vector<TypePackId>& packs, Location location);
@@ -336,7 +336,7 @@ public:
      * @param location the location where the require is taking place; used for
      * error locations.
      **/
-    TypeId resolveModule(const ModuleInfo& module, const Location& location);
+    TypeId resolveModule(const ModuleInfo& info, const Location& location);
 
     void reportError(TypeErrorData&& data, const Location& location);
     void reportError(TypeError e);
@@ -420,6 +420,11 @@ public:
     void throwUserCancelError() const;
 
     ToStringOptions opts;
+
+    void fillInDiscriminantTypes(
+        NotNull<const Constraint> constraint,
+        const std::vector<std::optional<TypeId>>& discriminantTypes
+    );
 };
 
 void dump(NotNull<Scope> rootScope, struct ToStringOptions& opts);

Analysis/include/Luau/DataFlowGraph.h

@@ -6,6 +6,7 @@
 #include "Luau/ControlFlow.h"
 #include "Luau/DenseHash.h"
 #include "Luau/Def.h"
+#include "Luau/NotNull.h"
 #include "Luau/Symbol.h"
 #include "Luau/TypedAllocator.h"
 
@@ -48,13 +49,13 @@ struct DataFlowGraph
     const RefinementKey* getRefinementKey(const AstExpr* expr) const;
 
 private:
-    DataFlowGraph() = default;
+    DataFlowGraph(NotNull<DefArena> defArena, NotNull<RefinementKeyArena> keyArena);
 
     DataFlowGraph(const DataFlowGraph&) = delete;
     DataFlowGraph& operator=(const DataFlowGraph&) = delete;
 
-    DefArena defArena;
-    RefinementKeyArena keyArena;
+    NotNull<DefArena> defArena;
+    NotNull<RefinementKeyArena> keyArena;
 
     DenseHashMap<const AstExpr*, const Def*> astDefs{nullptr};
 
@@ -110,30 +111,22 @@ using ScopeStack = std::vector<DfgScope*>;
 
 struct DataFlowGraphBuilder
 {
-    static DataFlowGraph build(AstStatBlock* root, NotNull<struct InternalErrorReporter> handle);
-
-    /**
-     * This method is identical to the build method above, but returns a pair of dfg, scopes as the data flow graph
-     * here is intended to live on the module between runs of typechecking. Before, the DFG only needed to live as
-     * long as the typecheck, but in a world with incremental typechecking, we need the information on the dfg to incrementally
-     * typecheck small fragments of code.
-     * @param block - pointer to the ast to build the dfg for
-     * @param handle - for raising internal errors while building the dfg
-     */
-    static std::pair<std::shared_ptr<DataFlowGraph>, std::vector<std::unique_ptr<DfgScope>>> buildShared(
+    static DataFlowGraph build(
         AstStatBlock* block,
-        NotNull<InternalErrorReporter> handle
+        NotNull<DefArena> defArena,
+        NotNull<RefinementKeyArena> keyArena,
+        NotNull<struct InternalErrorReporter> handle
     );
 
 private:
-    DataFlowGraphBuilder() = default;
+    DataFlowGraphBuilder(NotNull<DefArena> defArena, NotNull<RefinementKeyArena> keyArena);
 
     DataFlowGraphBuilder(const DataFlowGraphBuilder&) = delete;
     DataFlowGraphBuilder& operator=(const DataFlowGraphBuilder&) = delete;
 
     DataFlowGraph graph;
-    NotNull<DefArena> defArena{&graph.defArena};
-    NotNull<RefinementKeyArena> keyArena{&graph.keyArena};
+    NotNull<DefArena> defArena;
+    NotNull<RefinementKeyArena> keyArena;
 
     struct InternalErrorReporter* handle = nullptr;
 

Analysis/include/Luau/EqSatSimplificationImpl.h

@@ -53,7 +53,7 @@ LUAU_EQSAT_NODE_SET(Intersection);
 
 LUAU_EQSAT_NODE_ARRAY(Negation, 1);
 
-LUAU_EQSAT_NODE_ATOM_WITH_VECTOR(TTypeFun, const TypeFunction*);
+LUAU_EQSAT_NODE_ATOM_WITH_VECTOR(TTypeFun, std::shared_ptr<const TypeFunctionInstanceType>);
 
 LUAU_EQSAT_UNIT(TNoRefine);
 LUAU_EQSAT_UNIT(Invalid);
@@ -105,6 +105,9 @@ private:
     std::vector<Id> storage;
 };
 
+template <typename L>
+using Node = EqSat::Node<L>;
+
 using EType = EqSat::Language<
     TNil,
     TBoolean,
@@ -146,7 +149,7 @@ using EType = EqSat::Language<
 struct StringCache
 {
     Allocator allocator;
-    DenseHashMap<size_t, StringId> strings{{}};
+    DenseHashMap<std::string_view, StringId> strings{{}};
     std::vector<std::string_view> views;
 
     StringId add(std::string_view s);
@@ -171,6 +174,9 @@ struct Subst
     Id eclass;
     Id newClass;
 
+    // The node into eclass which is boring, if any
+    std::optional<size_t> boringIndex;
+
     std::string desc;
 
     Subst(Id eclass, Id newClass, std::string desc = "");
@@ -211,6 +217,7 @@ struct Simplifier
     void subst(Id from, Id to);
     void subst(Id from, Id to, const std::string& ruleName);
     void subst(Id from, Id to, const std::string& ruleName, const std::unordered_map<Id, size_t>& forceNodes);
+    void subst(Id from, size_t boringIndex, Id to, const std::string& ruleName, const std::unordered_map<Id, size_t>& forceNodes);
 
     void unionClasses(std::vector<Id>& hereParts, Id there);
 
@@ -218,6 +225,7 @@ struct Simplifier
     void simplifyUnion(Id id);
     void uninhabitedIntersection(Id id);
     void intersectWithNegatedClass(Id id);
+    void intersectWithNegatedAtom(Id id);
     void intersectWithNoRefine(Id id);
     void cyclicIntersectionOfUnion(Id id);
     void cyclicUnionOfIntersection(Id id);
@@ -228,6 +236,7 @@ struct Simplifier
     void unneededTableModification(Id id);
     void builtinTypeFunctions(Id id);
     void iffyTypeFunctions(Id id);
+    void strictMetamethods(Id id);
 };
 
 template<typename Tag>
@@ -293,13 +302,13 @@ QueryIterator<Tag>::QueryIterator(EGraph* egraph_, Id eclass)
 
     for (const auto& enode : ecl.nodes)
     {
-        if (enode.index() < idx)
+        if (enode.node.index() < idx)
             ++index;
         else
             break;
     }
 
-    if (index >= ecl.nodes.size() || ecl.nodes[index].index() != idx)
+    if (index >= ecl.nodes.size() || ecl.nodes[index].node.index() != idx)
     {
         egraph = nullptr;
         index = 0;
@@ -329,7 +338,7 @@ std::pair<const Tag*, size_t> QueryIterator<Tag>::operator*() const
     EGraph::EClassT& ecl = (*egraph)[eclass];
 
     LUAU_ASSERT(index < ecl.nodes.size());
-    auto& enode = ecl.nodes[index];
+    auto& enode = ecl.nodes[index].node;
     Tag* result = enode.template get<Tag>();
     LUAU_ASSERT(result);
     return {result, index};
@@ -341,12 +350,16 @@ QueryIterator<Tag>& QueryIterator<Tag>::operator++()
 {
     const auto& ecl = (*egraph)[eclass];
 
-    ++index;
-    if (index >= ecl.nodes.size() || ecl.nodes[index].index() != EType::VariantTy::getTypeId<Tag>())
+    do
     {
-        egraph = nullptr;
-        index = 0;
-    }
+        ++index;
+        if (index >= ecl.nodes.size() || ecl.nodes[index].node.index() != EType::VariantTy::getTypeId<Tag>())
+        {
+            egraph = nullptr;
+            index = 0;
+            break;
+        }
+    } while (ecl.nodes[index].boring);
 
     return *this;
 }

Analysis/include/Luau/FragmentAutocomplete.h

@@ -15,6 +15,12 @@ namespace Luau
 {
 struct FrontendOptions;
 
+enum class FragmentTypeCheckStatus
+{
+    SkipAutocomplete,
+    Success,
+};
+
 struct FragmentAutocompleteAncestryResult
 {
     DenseHashMap<AstName, AstLocal*> localMap{AstName()};
@@ -29,6 +35,7 @@ struct FragmentParseResult
     AstStatBlock* root = nullptr;
     std::vector<AstNode*> ancestry;
     AstStat* nearestStatement = nullptr;
+    std::vector<Comment> commentLocations;
     std::unique_ptr<Allocator> alloc = std::make_unique<Allocator>();
 };
 
@@ -49,14 +56,14 @@ struct FragmentAutocompleteResult
 
 FragmentAutocompleteAncestryResult findAncestryForFragmentParse(AstStatBlock* root, const Position& cursorPos);
 
-FragmentParseResult parseFragment(
+std::optional<FragmentParseResult> parseFragment(
     const SourceModule& srcModule,
     std::string_view src,
     const Position& cursorPos,
     std::optional<Position> fragmentEndPosition
 );
 
-FragmentTypeCheckResult typecheckFragment(
+std::pair<FragmentTypeCheckStatus, FragmentTypeCheckResult> typecheckFragment(
     Frontend& frontend,
     const ModuleName& moduleName,
     const Position& cursorPos,

Analysis/include/Luau/Frontend.h

@@ -7,6 +7,7 @@
 #include "Luau/ModuleResolver.h"
 #include "Luau/RequireTracer.h"
 #include "Luau/Scope.h"
+#include "Luau/Set.h"
 #include "Luau/TypeCheckLimits.h"
 #include "Luau/Variant.h"
 #include "Luau/AnyTypeSummary.h"
@@ -56,13 +57,32 @@ struct SourceNode
         return forAutocomplete ? dirtyModuleForAutocomplete : dirtyModule;
     }
 
+    bool hasInvalidModuleDependency(bool forAutocomplete) const
+    {
+        return forAutocomplete ? invalidModuleDependencyForAutocomplete : invalidModuleDependency;
+    }
+
+    void setInvalidModuleDependency(bool value, bool forAutocomplete)
+    {
+        if (forAutocomplete)
+            invalidModuleDependencyForAutocomplete = value;
+        else
+            invalidModuleDependency = value;
+    }
+
     ModuleName name;
     std::string humanReadableName;
     DenseHashSet<ModuleName> requireSet{{}};
     std::vector<std::pair<ModuleName, Location>> requireLocations;
+    Set<ModuleName> dependents{{}};
+
     bool dirtySourceModule = true;
     bool dirtyModule = true;
     bool dirtyModuleForAutocomplete = true;
+
+    bool invalidModuleDependency = true;
+    bool invalidModuleDependencyForAutocomplete = true;
+
     double autocompleteLimitsMult = 1.0;
 };
 
@@ -117,7 +137,7 @@ struct FrontendModuleResolver : ModuleResolver
     std::optional<ModuleInfo> resolveModuleInfo(const ModuleName& currentModuleName, const AstExpr& pathExpr) override;
     std::string getHumanReadableModuleName(const ModuleName& moduleName) const override;
 
-    void setModule(const ModuleName& moduleName, ModulePtr module);
+    bool setModule(const ModuleName& moduleName, ModulePtr module);
     void clearModules();
 
 private:
@@ -151,9 +171,13 @@ struct Frontend
     // Parse and typecheck module graph
     CheckResult check(const ModuleName& name, std::optional<FrontendOptions> optionOverride = {}); // new shininess
 
+    bool allModuleDependenciesValid(const ModuleName& name, bool forAutocomplete = false) const;
+
     bool isDirty(const ModuleName& name, bool forAutocomplete = false) const;
     void markDirty(const ModuleName& name, std::vector<ModuleName>* markedDirty = nullptr);
 
+    void traverseDependents(const ModuleName& name, std::function<bool(SourceNode&)> processSubtree);
+
     /** Borrow a pointer into the SourceModule cache.
      *
      * Returns nullptr if we don't have it.  This could mean that the script

Analysis/include/Luau/Module.h

@@ -16,6 +16,8 @@
 #include <unordered_map>
 #include <optional>
 
+LUAU_FASTFLAG(LuauIncrementalAutocompleteCommentDetection)
+
 namespace Luau
 {
 
@@ -55,6 +57,7 @@ struct SourceModule
     }
 };
 
+bool isWithinComment(const std::vector<Comment>& commentLocations, Position pos);
 bool isWithinComment(const SourceModule& sourceModule, Position pos);
 bool isWithinComment(const ParseResult& result, Position pos);
 
@@ -136,6 +139,11 @@ struct Module
     TypePackId returnType = nullptr;
     std::unordered_map<Name, TypeFun> exportedTypeBindings;
 
+    // Arenas related to the DFG must persist after the DFG no longer exists, as
+    // Module objects maintain raw pointers to objects in these arenas.
+    DefArena defArena;
+    RefinementKeyArena keyArena;
+
     bool hasModuleScope() const;
     ScopePtr getModuleScope() const;
 

Analysis/include/Luau/NonStrictTypeChecker.h

@@ -15,6 +15,7 @@ struct TypeCheckLimits;
 
 void checkNonStrict(
     NotNull<BuiltinTypes> builtinTypes,
+    NotNull<Simplifier> simplifier,
     NotNull<TypeFunctionRuntime> typeFunctionRuntime,
     NotNull<InternalErrorReporter> ice,
     NotNull<UnifierSharedState> unifierState,

Analysis/include/Luau/Normalize.h

@@ -1,6 +1,7 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #pragma once
 
+#include "Luau/EqSatSimplification.h"
 #include "Luau/NotNull.h"
 #include "Luau/Set.h"
 #include "Luau/TypeFwd.h"
@@ -21,8 +22,22 @@ struct Scope;
 
 using ModulePtr = std::shared_ptr<Module>;
 
-bool isSubtype(TypeId subTy, TypeId superTy, NotNull<Scope> scope, NotNull<BuiltinTypes> builtinTypes, InternalErrorReporter& ice);
-bool isSubtype(TypePackId subTy, TypePackId superTy, NotNull<Scope> scope, NotNull<BuiltinTypes> builtinTypes, InternalErrorReporter& ice);
+bool isSubtype(
+    TypeId subTy,
+    TypeId superTy,
+    NotNull<Scope> scope,
+    NotNull<BuiltinTypes> builtinTypes,
+    NotNull<Simplifier> simplifier,
+    InternalErrorReporter& ice
+);
+bool isSubtype(
+    TypePackId subPack,
+    TypePackId superPack,
+    NotNull<Scope> scope,
+    NotNull<BuiltinTypes> builtinTypes,
+    NotNull<Simplifier> simplifier,
+    InternalErrorReporter& ice
+);
 
 class TypeIds
 {

Analysis/include/Luau/OverloadResolution.h

@@ -2,12 +2,13 @@
 #pragma once
 
 #include "Luau/Ast.h"
-#include "Luau/InsertionOrderedMap.h"
-#include "Luau/NotNull.h"
-#include "Luau/TypeFwd.h"
-#include "Luau/Location.h"
+#include "Luau/EqSatSimplification.h"
 #include "Luau/Error.h"
+#include "Luau/InsertionOrderedMap.h"
+#include "Luau/Location.h"
+#include "Luau/NotNull.h"
 #include "Luau/Subtyping.h"
+#include "Luau/TypeFwd.h"
 
 namespace Luau
 {
@@ -34,6 +35,7 @@ struct OverloadResolver
     OverloadResolver(
         NotNull<BuiltinTypes> builtinTypes,
         NotNull<TypeArena> arena,
+        NotNull<Simplifier> simplifier,
         NotNull<Normalizer> normalizer,
         NotNull<TypeFunctionRuntime> typeFunctionRuntime,
         NotNull<Scope> scope,
@@ -44,6 +46,7 @@ struct OverloadResolver
 
     NotNull<BuiltinTypes> builtinTypes;
     NotNull<TypeArena> arena;
+    NotNull<Simplifier> simplifier;
     NotNull<Normalizer> normalizer;
     NotNull<TypeFunctionRuntime> typeFunctionRuntime;
     NotNull<Scope> scope;
@@ -110,6 +113,7 @@ struct SolveResult
 SolveResult solveFunctionCall(
     NotNull<TypeArena> arena,
     NotNull<BuiltinTypes> builtinTypes,
+    NotNull<Simplifier> simplifier,
     NotNull<Normalizer> normalizer,
     NotNull<TypeFunctionRuntime> typeFunctionRuntime,
     NotNull<InternalErrorReporter> iceReporter,

Analysis/include/Luau/Scope.h

@@ -85,12 +85,18 @@ struct Scope
     void inheritAssignments(const ScopePtr& childScope);
     void inheritRefinements(const ScopePtr& childScope);
 
+    // Track globals that should emit warnings during type checking.
+    DenseHashSet<std::string> globalsToWarn{""};
+    bool shouldWarnGlobal(std::string name) const;
+
     // For mutually recursive type aliases, it's important that
     // they use the same types for the same names.
     // For instance, in `type Tree<T> { data: T, children: Forest<T> } type Forest<T> = {Tree<T>}`
     // we need that the generic type `T` in both cases is the same, so we use a cache.
     std::unordered_map<Name, TypeId> typeAliasTypeParameters;
     std::unordered_map<Name, TypePackId> typeAliasTypePackParameters;
+
+    std::optional<std::vector<TypeId>> interiorFreeTypes;
 };
 
 // Returns true iff the left scope encloses the right scope.  A Scope* equal to

Analysis/include/Luau/Simplify.h

@@ -19,10 +19,10 @@ struct SimplifyResult
     DenseHashSet<TypeId> blockedTypes;
 };
 
-SimplifyResult simplifyIntersection(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, TypeId ty, TypeId discriminant);
+SimplifyResult simplifyIntersection(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, TypeId left, TypeId right);
 SimplifyResult simplifyIntersection(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, std::set<TypeId> parts);
 
-SimplifyResult simplifyUnion(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, TypeId ty, TypeId discriminant);
+SimplifyResult simplifyUnion(NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, TypeId left, TypeId right);
 
 enum class Relation
 {

Analysis/include/Luau/Subtyping.h

@@ -1,13 +1,14 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #pragma once
 
+#include "Luau/DenseHash.h"
+#include "Luau/EqSatSimplification.h"
 #include "Luau/Set.h"
+#include "Luau/TypeCheckLimits.h"
+#include "Luau/TypeFunction.h"
 #include "Luau/TypeFwd.h"
 #include "Luau/TypePairHash.h"
 #include "Luau/TypePath.h"
-#include "Luau/TypeFunction.h"
-#include "Luau/TypeCheckLimits.h"
-#include "Luau/DenseHash.h"
 
 #include <vector>
 #include <optional>
@@ -134,6 +135,7 @@ struct Subtyping
 {
     NotNull<BuiltinTypes> builtinTypes;
     NotNull<TypeArena> arena;
+    NotNull<Simplifier> simplifier;
     NotNull<Normalizer> normalizer;
     NotNull<TypeFunctionRuntime> typeFunctionRuntime;
     NotNull<InternalErrorReporter> iceReporter;
@@ -155,6 +157,7 @@ struct Subtyping
     Subtyping(
         NotNull<BuiltinTypes> builtinTypes,
         NotNull<TypeArena> typeArena,
+        NotNull<Simplifier> simplifier,
         NotNull<Normalizer> normalizer,
         NotNull<TypeFunctionRuntime> typeFunctionRuntime,
         NotNull<InternalErrorReporter> iceReporter

Analysis/include/Luau/Type.h

@@ -69,12 +69,16 @@ using Name = std::string;
 // A free type is one whose exact shape has yet to be fully determined.
 struct FreeType
 {
+    // New constructors
+    explicit FreeType(TypeLevel level, TypeId lowerBound, TypeId upperBound);
+    // This one got promoted to explicit
+    explicit FreeType(Scope* scope, TypeId lowerBound, TypeId upperBound);
+    explicit FreeType(Scope* scope, TypeLevel level, TypeId lowerBound, TypeId upperBound);
+    // Old constructors
     explicit FreeType(TypeLevel level);
     explicit FreeType(Scope* scope);
     FreeType(Scope* scope, TypeLevel level);
 
-    FreeType(Scope* scope, TypeId lowerBound, TypeId upperBound);
-
     int index;
     TypeLevel level;
     Scope* scope = nullptr;
@@ -131,14 +135,14 @@ struct BlockedType
     BlockedType();
     int index;
 
-    Constraint* getOwner() const;
-    void setOwner(Constraint* newOwner);
-    void replaceOwner(Constraint* newOwner);
+    const Constraint* getOwner() const;
+    void setOwner(const Constraint* newOwner);
+    void replaceOwner(const Constraint* newOwner);
 
 private:
     // The constraint that is intended to unblock this type. Other constraints
     // should block on this constraint if present.
-    Constraint* owner = nullptr;
+    const Constraint* owner = nullptr;
 };
 
 struct PrimitiveType
@@ -279,9 +283,6 @@ struct WithPredicate
     }
 };
 
-using MagicFunction = std::function<std::optional<
-    WithPredicate<TypePackId>>(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>)>;
-
 struct MagicFunctionCallContext
 {
     NotNull<struct ConstraintSolver> solver;
@@ -291,7 +292,6 @@ struct MagicFunctionCallContext
     TypePackId result;
 };
 
-using DcrMagicFunction = std::function<bool(MagicFunctionCallContext)>;
 struct MagicRefinementContext
 {
     NotNull<Scope> scope;
@@ -308,8 +308,29 @@ struct MagicFunctionTypeCheckContext
     NotNull<Scope> checkScope;
 };
 
-using DcrMagicRefinement = void (*)(const MagicRefinementContext&);
-using DcrMagicFunctionTypeCheck = std::function<void(const MagicFunctionTypeCheckContext&)>;
+struct MagicFunction
+{
+    virtual std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) = 0;
+
+    // Callback to allow custom typechecking of builtin function calls whose argument types
+    // will only be resolved after constraint solving. For example, the arguments to string.format
+    // have types that can only be decided after parsing the format string and unifying
+    // with the passed in values, but the correctness of the call can only be decided after
+    // all the types have been finalized.
+    virtual bool infer(const MagicFunctionCallContext&) = 0;
+    virtual void refine(const MagicRefinementContext&) {}
+
+    // If a magic function needs to do its own special typechecking, do it here.
+    // Returns true if magic typechecking was performed.  Return false if the
+    // default typechecking logic should run.
+    virtual bool typeCheck(const MagicFunctionTypeCheckContext&)
+    {
+        return false;
+    }
+
+    virtual ~MagicFunction() {}
+};
+
 struct FunctionType
 {
     // Global monomorphic function
@@ -367,16 +388,7 @@ struct FunctionType
     Scope* scope = nullptr;
     TypePackId argTypes;
     TypePackId retTypes;
-    MagicFunction magicFunction = nullptr;
-    DcrMagicFunction dcrMagicFunction = nullptr;
-    DcrMagicRefinement dcrMagicRefinement = nullptr;
-
-    // Callback to allow custom typechecking of builtin function calls whose argument types
-    // will only be resolved after constraint solving. For example, the arguments to string.format
-    // have types that can only be decided after parsing the format string and unifying
-    // with the passed in values, but the correctness of the call can only be decided after
-    // all the types have been finalized.
-    DcrMagicFunctionTypeCheck dcrMagicTypeCheck = nullptr;
+    std::shared_ptr<MagicFunction> magic = nullptr;
 
     bool hasSelf;
     // `hasNoFreeOrGenericTypes` should be true if and only if the type does not have any free or generic types present inside it.
@@ -608,7 +620,8 @@ struct UserDefinedFunctionData
     // References to AST elements are owned by the Module allocator which also stores this type
     AstStatTypeFunction* definition = nullptr;
 
-    DenseHashMap<Name, AstStatTypeFunction*> environment{""};
+    DenseHashMap<Name, std::pair<AstStatTypeFunction*, size_t>> environment{""};
+    DenseHashMap<Name, AstStatTypeFunction*> environment_DEPRECATED{""};
 };
 
 /**
@@ -625,7 +638,7 @@ struct TypeFunctionInstanceType
     std::vector<TypeId> typeArguments;
     std::vector<TypePackId> packArguments;
 
-    std::optional<AstName> userFuncName;          // Name of the user-defined type function; only available for UDTFs
+    std::optional<AstName> userFuncName; // Name of the user-defined type function; only available for UDTFs
     UserDefinedFunctionData userFuncData;
 
     TypeFunctionInstanceType(

Analysis/include/Luau/TypeArena.h

@@ -32,9 +32,13 @@ struct TypeArena
 
     TypeId addTV(Type&& tv);
 
-    TypeId freshType(TypeLevel level);
-    TypeId freshType(Scope* scope);
-    TypeId freshType(Scope* scope, TypeLevel level);
+    TypeId freshType(NotNull<BuiltinTypes> builtins, TypeLevel level);
+    TypeId freshType(NotNull<BuiltinTypes> builtins, Scope* scope);
+    TypeId freshType(NotNull<BuiltinTypes> builtins, Scope* scope, TypeLevel level);
+
+    TypeId freshType_DEPRECATED(TypeLevel level);
+    TypeId freshType_DEPRECATED(Scope* scope);
+    TypeId freshType_DEPRECATED(Scope* scope, TypeLevel level);
 
     TypePackId freshTypePack(Scope* scope);
 

Analysis/include/Luau/TypeChecker2.h

@@ -2,15 +2,16 @@
 
 #pragma once
 
-#include "Luau/Error.h"
-#include "Luau/NotNull.h"
 #include "Luau/Common.h"
-#include "Luau/TypeUtils.h"
+#include "Luau/EqSatSimplification.h"
+#include "Luau/Error.h"
+#include "Luau/Normalize.h"
+#include "Luau/NotNull.h"
+#include "Luau/Subtyping.h"
 #include "Luau/Type.h"
 #include "Luau/TypeFwd.h"
 #include "Luau/TypeOrPack.h"
-#include "Luau/Normalize.h"
-#include "Luau/Subtyping.h"
+#include "Luau/TypeUtils.h"
 
 namespace Luau
 {
@@ -60,8 +61,9 @@ struct Reasonings
 
 void check(
     NotNull<BuiltinTypes> builtinTypes,
+    NotNull<Simplifier> simplifier,
     NotNull<TypeFunctionRuntime> typeFunctionRuntime,
-    NotNull<UnifierSharedState> sharedState,
+    NotNull<UnifierSharedState> unifierState,
     NotNull<TypeCheckLimits> limits,
     DcrLogger* logger,
     const SourceModule& sourceModule,
@@ -71,6 +73,7 @@ void check(
 struct TypeChecker2
 {
     NotNull<BuiltinTypes> builtinTypes;
+    NotNull<Simplifier> simplifier;
     NotNull<TypeFunctionRuntime> typeFunctionRuntime;
     DcrLogger* logger;
     const NotNull<TypeCheckLimits> limits;
@@ -90,6 +93,7 @@ struct TypeChecker2
 
     TypeChecker2(
         NotNull<BuiltinTypes> builtinTypes,
+        NotNull<Simplifier> simplifier,
         NotNull<TypeFunctionRuntime> typeFunctionRuntime,
         NotNull<UnifierSharedState> unifierState,
         NotNull<TypeCheckLimits> limits,
@@ -112,14 +116,14 @@ private:
     std::optional<StackPusher> pushStack(AstNode* node);
     void checkForInternalTypeFunction(TypeId ty, Location location);
     TypeId checkForTypeFunctionInhabitance(TypeId instance, Location location);
-    TypePackId lookupPack(AstExpr* expr);
+    TypePackId lookupPack(AstExpr* expr) const;
     TypeId lookupType(AstExpr* expr);
     TypeId lookupAnnotation(AstType* annotation);
-    std::optional<TypePackId> lookupPackAnnotation(AstTypePack* annotation);
-    TypeId lookupExpectedType(AstExpr* expr);
-    TypePackId lookupExpectedPack(AstExpr* expr, TypeArena& arena);
+    std::optional<TypePackId> lookupPackAnnotation(AstTypePack* annotation) const;
+    TypeId lookupExpectedType(AstExpr* expr) const;
+    TypePackId lookupExpectedPack(AstExpr* expr, TypeArena& arena) const;
     TypePackId reconstructPack(AstArray<AstExpr*> exprs, TypeArena& arena);
-    Scope* findInnermostScope(Location location);
+    Scope* findInnermostScope(Location location) const;
     void visit(AstStat* stat);
     void visit(AstStatIf* ifStatement);
     void visit(AstStatWhile* whileStatement);
@@ -156,7 +160,7 @@ private:
     void visit(AstExprVarargs* expr);
     void visitCall(AstExprCall* call);
     void visit(AstExprCall* call);
-    std::optional<TypeId> tryStripUnionFromNil(TypeId ty);
+    std::optional<TypeId> tryStripUnionFromNil(TypeId ty) const;
     TypeId stripFromNilAndReport(TypeId ty, const Location& location);
     void visitExprName(AstExpr* expr, Location location, const std::string& propName, ValueContext context, TypeId astIndexExprTy);
     void visit(AstExprIndexName* indexName, ValueContext context);
@@ -213,6 +217,9 @@ private:
         std::vector<TypeError>& errors
     );
 
+    // Avoid duplicate warnings being emitted for the same global variable.
+    DenseHashSet<std::string> warnedGlobals{""};
+
     void diagnoseMissingTableKey(UnknownProperty* utk, TypeErrorData& data) const;
     bool isErrorSuppressing(Location loc, TypeId ty);
     bool isErrorSuppressing(Location loc1, TypeId ty1, Location loc2, TypeId ty2);

Analysis/include/Luau/TypeFunction.h

@@ -2,6 +2,7 @@
 #pragma once
 
 #include "Luau/Constraint.h"
+#include "Luau/EqSatSimplification.h"
 #include "Luau/Error.h"
 #include "Luau/NotNull.h"
 #include "Luau/TypeCheckLimits.h"
@@ -41,9 +42,15 @@ struct TypeFunctionRuntime
 
     StateRef state;
 
+    // Set of functions which have their environment table initialized
+    DenseHashSet<AstStatTypeFunction*> initialized{nullptr};
+
     // Evaluation of type functions should only be performed in the absence of parse errors in the source module
     bool allowEvaluation = true;
 
+    // Output created by 'print' function
+    std::vector<std::string> messages;
+
 private:
     void prepareState();
 };
@@ -53,6 +60,7 @@ struct TypeFunctionContext
     NotNull<TypeArena> arena;
     NotNull<BuiltinTypes> builtins;
     NotNull<Scope> scope;
+    NotNull<Simplifier> simplifier;
     NotNull<Normalizer> normalizer;
     NotNull<TypeFunctionRuntime> typeFunctionRuntime;
     NotNull<InternalErrorReporter> ice;
@@ -63,7 +71,7 @@ struct TypeFunctionContext
     // The constraint being reduced in this run of the reduction
     const Constraint* constraint;
 
-    std::optional<AstName> userFuncName;          // Name of the user-defined type function; only available for UDTFs
+    std::optional<AstName> userFuncName; // Name of the user-defined type function; only available for UDTFs
 
     TypeFunctionContext(NotNull<ConstraintSolver> cs, NotNull<Scope> scope, NotNull<const Constraint> constraint);
 
@@ -71,6 +79,7 @@ struct TypeFunctionContext
         NotNull<TypeArena> arena,
         NotNull<BuiltinTypes> builtins,
         NotNull<Scope> scope,
+        NotNull<Simplifier> simplifier,
         NotNull<Normalizer> normalizer,
         NotNull<TypeFunctionRuntime> typeFunctionRuntime,
         NotNull<InternalErrorReporter> ice,
@@ -79,6 +88,7 @@ struct TypeFunctionContext
         : arena(arena)
         , builtins(builtins)
         , scope(scope)
+        , simplifier(simplifier)
         , normalizer(normalizer)
         , typeFunctionRuntime(typeFunctionRuntime)
         , ice(ice)
@@ -91,19 +101,31 @@ struct TypeFunctionContext
     NotNull<Constraint> pushConstraint(ConstraintV&& c) const;
 };
 
+enum class Reduction
+{
+    // The type function is either known to be reducible or the determination is blocked.
+    MaybeOk,
+    // The type function is known to be irreducible, but maybe not be erroneous, e.g. when it's over generics or free types.
+    Irreducible,
+    // The type function is known to be irreducible, and is definitely erroneous.
+    Erroneous,
+};
+
 /// Represents a reduction result, which may have successfully reduced the type,
 /// may have concretely failed to reduce the type, or may simply be stuck
 /// without more information.
 template<typename Ty>
 struct TypeFunctionReductionResult
 {
+
     /// The result of the reduction, if any. If this is nullopt, the type function
     /// could not be reduced.
     std::optional<Ty> result;
-    /// Whether the result is uninhabited: whether we know, unambiguously and
-    /// permanently, whether this type function reduction results in an
-    /// uninhabitable type. This will trigger an error to be reported.
-    bool uninhabited;
+    /// Indicates the status of this reduction: is `Reduction::Irreducible` if
+    /// the this result indicates the type function is irreducible, and
+    /// `Reduction::Erroneous` if this result indicates the type function is
+    /// erroneous. `Reduction::MaybeOk` otherwise.
+    Reduction reductionStatus;
     /// Any types that need to be progressed or mutated before the reduction may
     /// proceed.
     std::vector<TypeId> blockedTypes;
@@ -112,6 +134,8 @@ struct TypeFunctionReductionResult
     std::vector<TypePackId> blockedPacks;
     /// A runtime error message from user-defined type functions
     std::optional<std::string> error;
+    /// Messages printed out from user-defined type functions
+    std::vector<std::string> messages;
 };
 
 template<typename T>
@@ -145,6 +169,7 @@ struct TypePackFunction
 struct FunctionGraphReductionResult
 {
     ErrorVec errors;
+    ErrorVec messages;
     DenseHashSet<TypeId> blockedTypes{nullptr};
     DenseHashSet<TypePackId> blockedPacks{nullptr};
     DenseHashSet<TypeId> reducedTypes{nullptr};
@@ -216,6 +241,9 @@ struct BuiltinTypeFunctions
     TypeFunction indexFunc;
     TypeFunction rawgetFunc;
 
+    TypeFunction setmetatableFunc;
+    TypeFunction getmetatableFunc;
+
     void addToScope(NotNull<TypeArena> arena, NotNull<Scope> scope) const;
 };
 

Analysis/include/Luau/TypeFunctionRuntime.h

@@ -119,7 +119,14 @@ struct TypeFunctionVariadicTypePack
     TypeFunctionTypeId type;
 };
 
-using TypeFunctionTypePackVariant = Variant<TypeFunctionTypePack, TypeFunctionVariadicTypePack>;
+struct TypeFunctionGenericTypePack
+{
+    bool isNamed = false;
+
+    std::string name;
+};
+
+using TypeFunctionTypePackVariant = Variant<TypeFunctionTypePack, TypeFunctionVariadicTypePack, TypeFunctionGenericTypePack>;
 
 struct TypeFunctionTypePackVar
 {
@@ -135,6 +142,9 @@ struct TypeFunctionTypePackVar
 
 struct TypeFunctionFunctionType
 {
+    std::vector<TypeFunctionTypeId> generics;
+    std::vector<TypeFunctionTypePackId> genericPacks;
+
     TypeFunctionTypePackId argTypes;
     TypeFunctionTypePackId retTypes;
 };
@@ -210,6 +220,14 @@ struct TypeFunctionClassType
     std::string name;
 };
 
+struct TypeFunctionGenericType
+{
+    bool isNamed = false;
+    bool isPack = false;
+
+    std::string name;
+};
+
 using TypeFunctionTypeVariant = Luau::Variant<
     TypeFunctionPrimitiveType,
     TypeFunctionAnyType,
@@ -221,7 +239,8 @@ using TypeFunctionTypeVariant = Luau::Variant<
     TypeFunctionNegationType,
     TypeFunctionFunctionType,
     TypeFunctionTableType,
-    TypeFunctionClassType>;
+    TypeFunctionClassType,
+    TypeFunctionGenericType>;
 
 struct TypeFunctionType
 {

Analysis/include/Luau/TypeUtils.h

@@ -40,7 +40,7 @@ struct InConditionalContext
     TypeContext* typeContext;
     TypeContext oldValue;
 
-    InConditionalContext(TypeContext* c)
+    explicit InConditionalContext(TypeContext* c)
         : typeContext(c)
         , oldValue(*c)
     {
@@ -269,8 +269,8 @@ bool isLiteral(const AstExpr* expr);
 std::vector<TypeId> findBlockedTypesIn(AstExprTable* expr, NotNull<DenseHashMap<const AstExpr*, TypeId>> astTypes);
 
 /**
- * Given a function call and a mapping from expression to type, determine 
- * whether the type of any argument in said call in depends on a blocked types. 
+ * Given a function call and a mapping from expression to type, determine
+ * whether the type of any argument in said call in depends on a blocked types.
  * This is used as a precondition for bidirectional inference: be warned that
  * the behavior of this algorithm is tightly coupled to that of bidirectional
  * inference.
@@ -280,4 +280,13 @@ std::vector<TypeId> findBlockedTypesIn(AstExprTable* expr, NotNull<DenseHashMap<
  */
 std::vector<TypeId> findBlockedArgTypesIn(AstExprCall* expr, NotNull<DenseHashMap<const AstExpr*, TypeId>> astTypes);
 
+/**
+ * Given a scope and a free type, find the closest parent that has a present
+ * `interiorFreeTypes` and append the given type to said list. This list will
+ * be generalized when the requiste `GeneralizationConstraint` is resolved.
+ * @param scope Initial scope this free type was attached to
+ * @param ty Free type to track.
+ */
+void trackInteriorFreeType(Scope* scope, TypeId ty);
+
 } // namespace Luau

Analysis/include/Luau/VisitType.h

@@ -85,6 +85,8 @@ struct GenericTypeVisitor
     {
     }
 
+    virtual ~GenericTypeVisitor() {}
+
     virtual void cycle(TypeId) {}
     virtual void cycle(TypePackId) {}
 

Analysis/src/AnyTypeSummary.cpp

@@ -177,7 +177,6 @@ void AnyTypeSummary::visit(const Scope* scope, AstStatReturn* ret, const Module*
             }
         }
     }
-
 }
 
 void AnyTypeSummary::visit(const Scope* scope, AstStatLocal* local, const Module* module, NotNull<BuiltinTypes> builtinTypes)

Analysis/src/AstJsonEncoder.cpp

@@ -1161,6 +1161,19 @@ struct AstJsonEncoder : public AstVisitor
         );
     }
 
+    bool visit(class AstTypeGroup* node) override
+    {
+        writeNode(
+            node,
+            "AstTypeGroup",
+            [&]()
+            {
+                write("type", node->type);
+            }
+        );
+        return false;
+    }
+
     bool visit(class AstTypeSingletonBool* node) override
     {
         writeNode(

Analysis/src/AstQuery.cpp

@@ -13,7 +13,7 @@
 
 LUAU_FASTFLAG(LuauSolverV2)
 
-LUAU_FASTFLAGVARIABLE(LuauDocumentationAtPosition)
+LUAU_FASTFLAG(LuauExtendStatEndPosWithSemicolon)
 
 namespace Luau
 {
@@ -43,11 +43,26 @@ struct AutocompleteNodeFinder : public AstVisitor
 
     bool visit(AstStat* stat) override
     {
-        if (stat->location.begin < pos && pos <= stat->location.end)
+        if (FFlag::LuauExtendStatEndPosWithSemicolon)
         {
-            ancestry.push_back(stat);
-            return true;
+            // Consider 'local myLocal = 4;|' and 'local myLocal = 4', where '|' is the cursor position. In both cases, the cursor position is equal
+            // to `AstStatLocal.location.end`. However, in the first case (semicolon), we are starting a new statement, whilst in the second case
+            // (no semicolon) we are still part of the AstStatLocal, hence the different comparison check.
+            if (stat->location.begin < pos && (stat->hasSemicolon ? pos < stat->location.end : pos <= stat->location.end))
+            {
+                ancestry.push_back(stat);
+                return true;
+            }
         }
+        else
+        {
+            if (stat->location.begin < pos && pos <= stat->location.end)
+            {
+                ancestry.push_back(stat);
+                return true;
+            }
+        }
+
         return false;
     }
 
@@ -518,7 +533,6 @@ static std::optional<DocumentationSymbol> getMetatableDocumentation(
     const AstName& index
 )
 {
-    LUAU_ASSERT(FFlag::LuauDocumentationAtPosition);
     auto indexIt = mtable->props.find("__index");
     if (indexIt == mtable->props.end())
         return std::nullopt;
@@ -575,26 +589,7 @@ std::optional<DocumentationSymbol> getDocumentationSymbolAtPosition(const Source
                 }
                 else if (const ClassType* ctv = get<ClassType>(parentTy))
                 {
-                    if (FFlag::LuauDocumentationAtPosition)
-                    {
-                        while (ctv)
-                        {
-                            if (auto propIt = ctv->props.find(indexName->index.value); propIt != ctv->props.end())
-                            {
-                                if (FFlag::LuauSolverV2)
-                                {
-                                    if (auto ty = propIt->second.readTy)
-                                        return checkOverloadedDocumentationSymbol(module, *ty, parentExpr, propIt->second.documentationSymbol);
-                                }
-                                else
-                                    return checkOverloadedDocumentationSymbol(
-                                        module, propIt->second.type(), parentExpr, propIt->second.documentationSymbol
-                                    );
-                            }
-                            ctv = ctv->parent ? Luau::get<Luau::ClassType>(*ctv->parent) : nullptr;
-                        }
-                    }
-                    else
+                    while (ctv)
                     {
                         if (auto propIt = ctv->props.find(indexName->index.value); propIt != ctv->props.end())
                         {
@@ -608,17 +603,15 @@ std::optional<DocumentationSymbol> getDocumentationSymbolAtPosition(const Source
                                     module, propIt->second.type(), parentExpr, propIt->second.documentationSymbol
                                 );
                         }
+                        ctv = ctv->parent ? Luau::get<Luau::ClassType>(*ctv->parent) : nullptr;
                     }
                 }
-                else if (FFlag::LuauDocumentationAtPosition)
+                else if (const PrimitiveType* ptv = get<PrimitiveType>(parentTy); ptv && ptv->metatable)
                 {
-                    if (const PrimitiveType* ptv = get<PrimitiveType>(parentTy); ptv && ptv->metatable)
+                    if (auto mtable = get<TableType>(*ptv->metatable))
                     {
-                        if (auto mtable = get<TableType>(*ptv->metatable))
-                        {
-                            if (std::optional<std::string> docSymbol = getMetatableDocumentation(module, parentExpr, mtable, indexName->index))
-                                return docSymbol;
-                        }
+                        if (std::optional<std::string> docSymbol = getMetatableDocumentation(module, parentExpr, mtable, indexName->index))
+                            return docSymbol;
                     }
                 }
             }

Analysis/src/AutocompleteCore.cpp

@@ -25,6 +25,7 @@ LUAU_FASTINT(LuauTypeInferIterationLimit)
 LUAU_FASTINT(LuauTypeInferRecursionLimit)
 
 LUAU_FASTFLAGVARIABLE(LuauAutocompleteRefactorsForIncrementalAutocomplete)
+LUAU_FASTFLAGVARIABLE(LuauAutocompleteUseLimits)
 
 static const std::unordered_set<std::string> kStatementStartingKeywords =
     {"while", "if", "local", "repeat", "function", "do", "for", "return", "break", "continue", "type", "export"};
@@ -150,6 +151,7 @@ static bool checkTypeMatch(TypeId subTy, TypeId superTy, NotNull<Scope> scope, T
 {
     InternalErrorReporter iceReporter;
     UnifierSharedState unifierState(&iceReporter);
+    SimplifierPtr simplifier = newSimplifier(NotNull{typeArena}, builtinTypes);
     Normalizer normalizer{typeArena, builtinTypes, NotNull{&unifierState}};
 
     if (FFlag::LuauSolverV2)
@@ -162,7 +164,9 @@ static bool checkTypeMatch(TypeId subTy, TypeId superTy, NotNull<Scope> scope, T
         unifierState.counters.recursionLimit = FInt::LuauTypeInferRecursionLimit;
         unifierState.counters.iterationLimit = FInt::LuauTypeInferIterationLimit;
 
-        Subtyping subtyping{builtinTypes, NotNull{typeArena}, NotNull{&normalizer}, NotNull{&typeFunctionRuntime}, NotNull{&iceReporter}};
+        Subtyping subtyping{
+            builtinTypes, NotNull{typeArena}, NotNull{simplifier.get()}, NotNull{&normalizer}, NotNull{&typeFunctionRuntime}, NotNull{&iceReporter}
+        };
 
         return subtyping.isSubtype(subTy, superTy, scope).isSubtype;
     }
@@ -174,6 +178,12 @@ static bool checkTypeMatch(TypeId subTy, TypeId superTy, NotNull<Scope> scope, T
         unifier.normalize = false;
         unifier.checkInhabited = false;
 
+        if (FFlag::LuauAutocompleteUseLimits)
+        {
+            unifierState.counters.recursionLimit = FInt::LuauTypeInferRecursionLimit;
+            unifierState.counters.iterationLimit = FInt::LuauTypeInferIterationLimit;
+        }
+
         return unifier.canUnify(subTy, superTy).empty();
     }
 }

Analysis/src/BuiltinDefinitions.cpp

@@ -29,50 +29,81 @@
  */
 
 LUAU_FASTFLAG(LuauSolverV2)
-LUAU_FASTFLAGVARIABLE(LuauTypestateBuiltins2)
-LUAU_FASTFLAGVARIABLE(LuauStringFormatArityFix)
+LUAU_FASTFLAGVARIABLE(LuauStringFormatErrorSuppression)
 LUAU_FASTFLAG(AutocompleteRequirePathSuggestions2)
-LUAU_FASTFLAG(LuauVectorDefinitionsExtra)
+LUAU_FASTFLAGVARIABLE(LuauTableCloneClonesType3)
+LUAU_FASTFLAG(LuauTrackInteriorFreeTypesOnScope)
+LUAU_FASTFLAGVARIABLE(LuauFreezeIgnorePersistent)
 
 namespace Luau
 {
 
-static std::optional<WithPredicate<TypePackId>> magicFunctionSelect(
-    TypeChecker& typechecker,
-    const ScopePtr& scope,
-    const AstExprCall& expr,
-    WithPredicate<TypePackId> withPredicate
-);
-static std::optional<WithPredicate<TypePackId>> magicFunctionSetMetaTable(
-    TypeChecker& typechecker,
-    const ScopePtr& scope,
-    const AstExprCall& expr,
-    WithPredicate<TypePackId> withPredicate
-);
-static std::optional<WithPredicate<TypePackId>> magicFunctionAssert(
-    TypeChecker& typechecker,
-    const ScopePtr& scope,
-    const AstExprCall& expr,
-    WithPredicate<TypePackId> withPredicate
-);
-static std::optional<WithPredicate<TypePackId>> magicFunctionPack(
-    TypeChecker& typechecker,
-    const ScopePtr& scope,
-    const AstExprCall& expr,
-    WithPredicate<TypePackId> withPredicate
-);
-static std::optional<WithPredicate<TypePackId>> magicFunctionRequire(
-    TypeChecker& typechecker,
-    const ScopePtr& scope,
-    const AstExprCall& expr,
-    WithPredicate<TypePackId> withPredicate
-);
+struct MagicSelect final : MagicFunction
+{
+    std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) override;
+    bool infer(const MagicFunctionCallContext& ctx) override;
+};
 
+struct MagicSetMetatable final : MagicFunction
+{
+    std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) override;
+    bool infer(const MagicFunctionCallContext& ctx) override;
+};
 
-static bool dcrMagicFunctionSelect(MagicFunctionCallContext context);
-static bool dcrMagicFunctionRequire(MagicFunctionCallContext context);
-static bool dcrMagicFunctionPack(MagicFunctionCallContext context);
-static bool dcrMagicFunctionFreeze(MagicFunctionCallContext context);
+struct MagicAssert final : MagicFunction
+{
+    std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) override;
+    bool infer(const MagicFunctionCallContext& ctx) override;
+};
+
+struct MagicPack final : MagicFunction
+{
+    std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) override;
+    bool infer(const MagicFunctionCallContext& ctx) override;
+};
+
+struct MagicRequire final : MagicFunction
+{
+    std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) override;
+    bool infer(const MagicFunctionCallContext& ctx) override;
+};
+
+struct MagicClone final : MagicFunction
+{
+    std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) override;
+    bool infer(const MagicFunctionCallContext& ctx) override;
+};
+
+struct MagicFreeze final : MagicFunction
+{
+    std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) override;
+    bool infer(const MagicFunctionCallContext& ctx) override;
+};
+
+struct MagicFormat final : MagicFunction
+{
+    std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) override;
+    bool infer(const MagicFunctionCallContext& ctx) override;
+    bool typeCheck(const MagicFunctionTypeCheckContext& ctx) override;
+};
+
+struct MagicMatch final : MagicFunction
+{
+    std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) override;
+    bool infer(const MagicFunctionCallContext& ctx) override;
+};
+
+struct MagicGmatch final : MagicFunction
+{
+    std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) override;
+    bool infer(const MagicFunctionCallContext& ctx) override;
+};
+
+struct MagicFind final : MagicFunction
+{
+    std::optional<WithPredicate<TypePackId>> handleOldSolver(struct TypeChecker&, const std::shared_ptr<struct Scope>&, const class AstExprCall&, WithPredicate<TypePackId>) override;
+    bool infer(const MagicFunctionCallContext& ctx) override;
+};
 
 TypeId makeUnion(TypeArena& arena, std::vector<TypeId>&& types)
 {
@@ -167,34 +198,10 @@ TypeId makeFunction(
     return arena.addType(std::move(ftv));
 }
 
-void attachMagicFunction(TypeId ty, MagicFunction fn)
+void attachMagicFunction(TypeId ty, std::shared_ptr<MagicFunction> magic)
 {
     if (auto ftv = getMutable<FunctionType>(ty))
-        ftv->magicFunction = fn;
-    else
-        LUAU_ASSERT(!"Got a non functional type");
-}
-
-void attachDcrMagicFunction(TypeId ty, DcrMagicFunction fn)
-{
-    if (auto ftv = getMutable<FunctionType>(ty))
-        ftv->dcrMagicFunction = fn;
-    else
-        LUAU_ASSERT(!"Got a non functional type");
-}
-
-void attachDcrMagicRefinement(TypeId ty, DcrMagicRefinement fn)
-{
-    if (auto ftv = getMutable<FunctionType>(ty))
-        ftv->dcrMagicRefinement = fn;
-    else
-        LUAU_ASSERT(!"Got a non functional type");
-}
-
-void attachDcrMagicFunctionTypeCheck(TypeId ty, DcrMagicFunctionTypeCheck fn)
-{
-    if (auto ftv = getMutable<FunctionType>(ty))
-        ftv->dcrMagicTypeCheck = fn;
+        ftv->magic = std::move(magic);
     else
         LUAU_ASSERT(!"Got a non functional type");
 }
@@ -301,28 +308,25 @@ void registerBuiltinGlobals(Frontend& frontend, GlobalTypes& globals, bool typeC
     addGlobalBinding(globals, "string", it->second.type(), "@luau");
 
     // Setup 'vector' metatable
-    if (FFlag::LuauVectorDefinitionsExtra)
+    if (auto it = globals.globalScope->exportedTypeBindings.find("vector"); it != globals.globalScope->exportedTypeBindings.end())
     {
-        if (auto it = globals.globalScope->exportedTypeBindings.find("vector"); it != globals.globalScope->exportedTypeBindings.end())
-        {
-            TypeId vectorTy = it->second.type;
-            ClassType* vectorCls = getMutable<ClassType>(vectorTy);
+        TypeId vectorTy = it->second.type;
+        ClassType* vectorCls = getMutable<ClassType>(vectorTy);
 
-            vectorCls->metatable = arena.addType(TableType{{}, std::nullopt, TypeLevel{}, TableState::Sealed});
-            TableType* metatableTy = Luau::getMutable<TableType>(vectorCls->metatable);
+        vectorCls->metatable = arena.addType(TableType{{}, std::nullopt, TypeLevel{}, TableState::Sealed});
+        TableType* metatableTy = Luau::getMutable<TableType>(vectorCls->metatable);
 
-            metatableTy->props["__add"] = {makeFunction(arena, vectorTy, {vectorTy}, {vectorTy})};
-            metatableTy->props["__sub"] = {makeFunction(arena, vectorTy, {vectorTy}, {vectorTy})};
-            metatableTy->props["__unm"] = {makeFunction(arena, vectorTy, {}, {vectorTy})};
+        metatableTy->props["__add"] = {makeFunction(arena, vectorTy, {vectorTy}, {vectorTy})};
+        metatableTy->props["__sub"] = {makeFunction(arena, vectorTy, {vectorTy}, {vectorTy})};
+        metatableTy->props["__unm"] = {makeFunction(arena, vectorTy, {}, {vectorTy})};
 
-            std::initializer_list<TypeId> mulOverloads{
-                makeFunction(arena, vectorTy, {vectorTy}, {vectorTy}),
-                makeFunction(arena, vectorTy, {builtinTypes->numberType}, {vectorTy}),
-            };
-            metatableTy->props["__mul"] = {makeIntersection(arena, mulOverloads)};
-            metatableTy->props["__div"] = {makeIntersection(arena, mulOverloads)};
-            metatableTy->props["__idiv"] = {makeIntersection(arena, mulOverloads)};
-        }
+        std::initializer_list<TypeId> mulOverloads{
+            makeFunction(arena, vectorTy, {vectorTy}, {vectorTy}),
+            makeFunction(arena, vectorTy, {builtinTypes->numberType}, {vectorTy}),
+        };
+        metatableTy->props["__mul"] = {makeIntersection(arena, mulOverloads)};
+        metatableTy->props["__div"] = {makeIntersection(arena, mulOverloads)};
+        metatableTy->props["__idiv"] = {makeIntersection(arena, mulOverloads)};
     }
 
     // next<K, V>(t: Table<K, V>, i: K?) -> (K?, V)
@@ -395,7 +399,7 @@ void registerBuiltinGlobals(Frontend& frontend, GlobalTypes& globals, bool typeC
         }
     }
 
-    attachMagicFunction(getGlobalBinding(globals, "assert"), magicFunctionAssert);
+    attachMagicFunction(getGlobalBinding(globals, "assert"), std::make_shared<MagicAssert>());
 
     if (FFlag::LuauSolverV2)
     {
@@ -411,9 +415,8 @@ void registerBuiltinGlobals(Frontend& frontend, GlobalTypes& globals, bool typeC
         addGlobalBinding(globals, "assert", assertTy, "@luau");
     }
 
-    attachMagicFunction(getGlobalBinding(globals, "setmetatable"), magicFunctionSetMetaTable);
-    attachMagicFunction(getGlobalBinding(globals, "select"), magicFunctionSelect);
-    attachDcrMagicFunction(getGlobalBinding(globals, "select"), dcrMagicFunctionSelect);
+    attachMagicFunction(getGlobalBinding(globals, "setmetatable"), std::make_shared<MagicSetMetatable>());
+    attachMagicFunction(getGlobalBinding(globals, "select"), std::make_shared<MagicSelect>());
 
     if (TableType* ttv = getMutable<TableType>(getGlobalBinding(globals, "table")))
     {
@@ -444,23 +447,21 @@ void registerBuiltinGlobals(Frontend& frontend, GlobalTypes& globals, bool typeC
         ttv->props["foreach"].deprecated = true;
         ttv->props["foreachi"].deprecated = true;
 
-        attachMagicFunction(ttv->props["pack"].type(), magicFunctionPack);
-        attachDcrMagicFunction(ttv->props["pack"].type(), dcrMagicFunctionPack);
-        if (FFlag::LuauTypestateBuiltins2)
-            attachDcrMagicFunction(ttv->props["freeze"].type(), dcrMagicFunctionFreeze);
+        attachMagicFunction(ttv->props["pack"].type(), std::make_shared<MagicPack>());
+        if (FFlag::LuauTableCloneClonesType3)
+            attachMagicFunction(ttv->props["clone"].type(), std::make_shared<MagicClone>());
+        attachMagicFunction(ttv->props["freeze"].type(), std::make_shared<MagicFreeze>());
     }
 
     if (FFlag::AutocompleteRequirePathSuggestions2)
     {
         TypeId requireTy = getGlobalBinding(globals, "require");
         attachTag(requireTy, kRequireTagName);
-        attachMagicFunction(requireTy, magicFunctionRequire);
-        attachDcrMagicFunction(requireTy, dcrMagicFunctionRequire);
+        attachMagicFunction(requireTy, std::make_shared<MagicRequire>());
     }
     else
     {
-        attachMagicFunction(getGlobalBinding(globals, "require"), magicFunctionRequire);
-        attachDcrMagicFunction(getGlobalBinding(globals, "require"), dcrMagicFunctionRequire);
+        attachMagicFunction(getGlobalBinding(globals, "require"), std::make_shared<MagicRequire>());
     }
 }
 
@@ -500,7 +501,7 @@ static std::vector<TypeId> parseFormatString(NotNull<BuiltinTypes> builtinTypes,
     return result;
 }
 
-std::optional<WithPredicate<TypePackId>> magicFunctionFormat(
+std::optional<WithPredicate<TypePackId>> MagicFormat::handleOldSolver(
     TypeChecker& typechecker,
     const ScopePtr& scope,
     const AstExprCall& expr,
@@ -550,7 +551,7 @@ std::optional<WithPredicate<TypePackId>> magicFunctionFormat(
     return WithPredicate<TypePackId>{arena.addTypePack({typechecker.stringType})};
 }
 
-static bool dcrMagicFunctionFormat(MagicFunctionCallContext context)
+bool MagicFormat::infer(const MagicFunctionCallContext& context)
 {
     TypeArena* arena = context.solver->arena;
 
@@ -594,7 +595,7 @@ static bool dcrMagicFunctionFormat(MagicFunctionCallContext context)
     return true;
 }
 
-static void dcrMagicFunctionTypeCheckFormat(MagicFunctionTypeCheckContext context)
+bool MagicFormat::typeCheck(const MagicFunctionTypeCheckContext& context)
 {
     AstExprConstantString* fmt = nullptr;
     if (auto index = context.callSite->func->as<AstExprIndexName>(); index && context.callSite->self)
@@ -610,9 +611,8 @@ static void dcrMagicFunctionTypeCheckFormat(MagicFunctionTypeCheckContext contex
 
     if (!fmt)
     {
-        if (FFlag::LuauStringFormatArityFix)
-            context.typechecker->reportError(CountMismatch{1, std::nullopt, 0, CountMismatch::Arg, true, "string.format"}, context.callSite->location);
-        return;
+        context.typechecker->reportError(CountMismatch{1, std::nullopt, 0, CountMismatch::Arg, true, "string.format"}, context.callSite->location);
+        return true;
     }
 
     std::vector<TypeId> expected = parseFormatString(context.builtinTypes, fmt->value.data, fmt->value.size);
@@ -629,12 +629,33 @@ static void dcrMagicFunctionTypeCheckFormat(MagicFunctionTypeCheckContext contex
         Location location = context.callSite->args.data[i + (calledWithSelf ? 0 : paramOffset)]->location;
         // use subtyping instead here
         SubtypingResult result = context.typechecker->subtyping->isSubtype(actualTy, expectedTy, context.checkScope);
+
         if (!result.isSubtype)
         {
-            Reasonings reasonings = context.typechecker->explainReasonings(actualTy, expectedTy, location, result);
-            context.typechecker->reportError(TypeMismatch{expectedTy, actualTy, reasonings.toString()}, location);
+            if (FFlag::LuauStringFormatErrorSuppression)
+            {
+                switch (shouldSuppressErrors(NotNull{&context.typechecker->normalizer}, actualTy))
+                {
+                    case ErrorSuppression::Suppress:
+                        break;
+                    case ErrorSuppression::NormalizationFailed:
+                        break;
+                    case ErrorSuppression::DoNotSuppress:
+                        Reasonings reasonings = context.typechecker->explainReasonings(actualTy, expectedTy, location, result);
+
+                        if (!reasonings.suppressed)
+                            context.typechecker->reportError(TypeMismatch{expectedTy, actualTy, reasonings.toString()}, location);
+                }
+            }
+            else
+            {
+                Reasonings reasonings = context.typechecker->explainReasonings(actualTy, expectedTy, location, result);
+                context.typechecker->reportError(TypeMismatch{expectedTy, actualTy, reasonings.toString()}, location);
+            }
         }
     }
+
+    return true;
 }
 
 static std::vector<TypeId> parsePatternString(NotNull<BuiltinTypes> builtinTypes, const char* data, size_t size)
@@ -697,7 +718,7 @@ static std::vector<TypeId> parsePatternString(NotNull<BuiltinTypes> builtinTypes
     return result;
 }
 
-static std::optional<WithPredicate<TypePackId>> magicFunctionGmatch(
+std::optional<WithPredicate<TypePackId>> MagicGmatch::handleOldSolver(
     TypeChecker& typechecker,
     const ScopePtr& scope,
     const AstExprCall& expr,
@@ -733,7 +754,7 @@ static std::optional<WithPredicate<TypePackId>> magicFunctionGmatch(
     return WithPredicate<TypePackId>{arena.addTypePack({iteratorType})};
 }
 
-static bool dcrMagicFunctionGmatch(MagicFunctionCallContext context)
+bool MagicGmatch::infer(const MagicFunctionCallContext& context)
 {
     const auto& [params, tail] = flatten(context.arguments);
 
@@ -766,7 +787,7 @@ static bool dcrMagicFunctionGmatch(MagicFunctionCallContext context)
     return true;
 }
 
-static std::optional<WithPredicate<TypePackId>> magicFunctionMatch(
+std::optional<WithPredicate<TypePackId>> MagicMatch::handleOldSolver(
     TypeChecker& typechecker,
     const ScopePtr& scope,
     const AstExprCall& expr,
@@ -806,7 +827,7 @@ static std::optional<WithPredicate<TypePackId>> magicFunctionMatch(
     return WithPredicate<TypePackId>{returnList};
 }
 
-static bool dcrMagicFunctionMatch(MagicFunctionCallContext context)
+bool MagicMatch::infer(const MagicFunctionCallContext& context)
 {
     const auto& [params, tail] = flatten(context.arguments);
 
@@ -842,7 +863,7 @@ static bool dcrMagicFunctionMatch(MagicFunctionCallContext context)
     return true;
 }
 
-static std::optional<WithPredicate<TypePackId>> magicFunctionFind(
+std::optional<WithPredicate<TypePackId>> MagicFind::handleOldSolver(
     TypeChecker& typechecker,
     const ScopePtr& scope,
     const AstExprCall& expr,
@@ -900,7 +921,7 @@ static std::optional<WithPredicate<TypePackId>> magicFunctionFind(
     return WithPredicate<TypePackId>{returnList};
 }
 
-static bool dcrMagicFunctionFind(MagicFunctionCallContext context)
+bool MagicFind::infer(const MagicFunctionCallContext& context)
 {
     const auto& [params, tail] = flatten(context.arguments);
 
@@ -977,11 +998,9 @@ TypeId makeStringMetatable(NotNull<BuiltinTypes> builtinTypes)
 
 
     FunctionType formatFTV{arena->addTypePack(TypePack{{stringType}, variadicTailPack}), oneStringPack};
-    formatFTV.magicFunction = &magicFunctionFormat;
     formatFTV.isCheckedFunction = true;
     const TypeId formatFn = arena->addType(formatFTV);
-    attachDcrMagicFunction(formatFn, dcrMagicFunctionFormat);
-    attachDcrMagicFunctionTypeCheck(formatFn, dcrMagicFunctionTypeCheckFormat);
+    attachMagicFunction(formatFn, std::make_shared<MagicFormat>());
 
 
     const TypeId stringToStringType = makeFunction(*arena, std::nullopt, {}, {}, {stringType}, {}, {stringType}, /* checked */ true);
@@ -995,16 +1014,14 @@ TypeId makeStringMetatable(NotNull<BuiltinTypes> builtinTypes)
         makeFunction(*arena, stringType, {}, {}, {stringType, replArgType, optionalNumber}, {}, {stringType, numberType}, /* checked */ false);
     const TypeId gmatchFunc =
         makeFunction(*arena, stringType, {}, {}, {stringType}, {}, {arena->addType(FunctionType{emptyPack, stringVariadicList})}, /* checked */ true);
-    attachMagicFunction(gmatchFunc, magicFunctionGmatch);
-    attachDcrMagicFunction(gmatchFunc, dcrMagicFunctionGmatch);
+    attachMagicFunction(gmatchFunc, std::make_shared<MagicGmatch>());
 
     FunctionType matchFuncTy{
         arena->addTypePack({stringType, stringType, optionalNumber}), arena->addTypePack(TypePackVar{VariadicTypePack{stringType}})
     };
     matchFuncTy.isCheckedFunction = true;
     const TypeId matchFunc = arena->addType(matchFuncTy);
-    attachMagicFunction(matchFunc, magicFunctionMatch);
-    attachDcrMagicFunction(matchFunc, dcrMagicFunctionMatch);
+    attachMagicFunction(matchFunc, std::make_shared<MagicMatch>());
 
     FunctionType findFuncTy{
         arena->addTypePack({stringType, stringType, optionalNumber, optionalBoolean}),
@@ -1012,8 +1029,7 @@ TypeId makeStringMetatable(NotNull<BuiltinTypes> builtinTypes)
     };
     findFuncTy.isCheckedFunction = true;
     const TypeId findFunc = arena->addType(findFuncTy);
-    attachMagicFunction(findFunc, magicFunctionFind);
-    attachDcrMagicFunction(findFunc, dcrMagicFunctionFind);
+    attachMagicFunction(findFunc, std::make_shared<MagicFind>());
 
     // string.byte : string -> number? -> number? -> ...number
     FunctionType stringDotByte{arena->addTypePack({stringType, optionalNumber, optionalNumber}), numberVariadicList};
@@ -1074,7 +1090,7 @@ TypeId makeStringMetatable(NotNull<BuiltinTypes> builtinTypes)
     return arena->addType(TableType{{{{"__index", {tableType}}}}, std::nullopt, TypeLevel{}, TableState::Sealed});
 }
 
-static std::optional<WithPredicate<TypePackId>> magicFunctionSelect(
+std::optional<WithPredicate<TypePackId>> MagicSelect::handleOldSolver(
     TypeChecker& typechecker,
     const ScopePtr& scope,
     const AstExprCall& expr,
@@ -1119,7 +1135,7 @@ static std::optional<WithPredicate<TypePackId>> magicFunctionSelect(
     return std::nullopt;
 }
 
-static bool dcrMagicFunctionSelect(MagicFunctionCallContext context)
+bool MagicSelect::infer(const MagicFunctionCallContext& context)
 {
     if (context.callSite->args.size <= 0)
     {
@@ -1164,7 +1180,7 @@ static bool dcrMagicFunctionSelect(MagicFunctionCallContext context)
     return false;
 }
 
-static std::optional<WithPredicate<TypePackId>> magicFunctionSetMetaTable(
+std::optional<WithPredicate<TypePackId>> MagicSetMetatable::handleOldSolver(
     TypeChecker& typechecker,
     const ScopePtr& scope,
     const AstExprCall& expr,
@@ -1246,7 +1262,12 @@ static std::optional<WithPredicate<TypePackId>> magicFunctionSetMetaTable(
     return WithPredicate<TypePackId>{arena.addTypePack({target})};
 }
 
-static std::optional<WithPredicate<TypePackId>> magicFunctionAssert(
+bool MagicSetMetatable::infer(const MagicFunctionCallContext&)
+{
+    return false;
+}
+
+std::optional<WithPredicate<TypePackId>> MagicAssert::handleOldSolver(
     TypeChecker& typechecker,
     const ScopePtr& scope,
     const AstExprCall& expr,
@@ -1280,7 +1301,12 @@ static std::optional<WithPredicate<TypePackId>> magicFunctionAssert(
     return WithPredicate<TypePackId>{arena.addTypePack(TypePack{std::move(head), tail})};
 }
 
-static std::optional<WithPredicate<TypePackId>> magicFunctionPack(
+bool MagicAssert::infer(const MagicFunctionCallContext&)
+{
+    return false;
+}
+
+std::optional<WithPredicate<TypePackId>> MagicPack::handleOldSolver(
     TypeChecker& typechecker,
     const ScopePtr& scope,
     const AstExprCall& expr,
@@ -1323,7 +1349,7 @@ static std::optional<WithPredicate<TypePackId>> magicFunctionPack(
     return WithPredicate<TypePackId>{arena.addTypePack({packedTable})};
 }
 
-static bool dcrMagicFunctionPack(MagicFunctionCallContext context)
+bool MagicPack::infer(const MagicFunctionCallContext& context)
 {
 
     TypeArena* arena = context.solver->arena;
@@ -1363,7 +1389,74 @@ static bool dcrMagicFunctionPack(MagicFunctionCallContext context)
     return true;
 }
 
-static std::optional<TypeId> freezeTable(TypeId inputType, MagicFunctionCallContext& context)
+std::optional<WithPredicate<TypePackId>> MagicClone::handleOldSolver(
+    TypeChecker& typechecker,
+    const ScopePtr& scope,
+    const AstExprCall& expr,
+    WithPredicate<TypePackId> withPredicate
+)
+{
+    LUAU_ASSERT(FFlag::LuauTableCloneClonesType3);
+
+    auto [paramPack, _predicates] = withPredicate;
+
+    TypeArena& arena = typechecker.currentModule->internalTypes;
+
+    const auto& [paramTypes, paramTail] = flatten(paramPack);
+    if (paramTypes.empty() || expr.args.size == 0)
+    {
+        typechecker.reportError(expr.argLocation, CountMismatch{1, std::nullopt, 0});
+        return std::nullopt;
+    }
+
+    TypeId inputType = follow(paramTypes[0]);
+
+    if (!get<TableType>(inputType))
+        return std::nullopt;
+
+    CloneState cloneState{typechecker.builtinTypes};
+    TypeId resultType = shallowClone(inputType, arena, cloneState);
+
+    TypePackId clonedTypePack = arena.addTypePack({resultType});
+    return WithPredicate<TypePackId>{clonedTypePack};
+}
+
+bool MagicClone::infer(const MagicFunctionCallContext& context)
+{
+    LUAU_ASSERT(FFlag::LuauTableCloneClonesType3);
+
+    TypeArena* arena = context.solver->arena;
+
+    const auto& [paramTypes, paramTail] = flatten(context.arguments);
+    if (paramTypes.empty() || context.callSite->args.size == 0)
+    {
+        context.solver->reportError(CountMismatch{1, std::nullopt, 0}, context.callSite->argLocation);
+        return false;
+    }
+
+    TypeId inputType = follow(paramTypes[0]);
+
+    if (!get<TableType>(inputType))
+        return false;
+
+    CloneState cloneState{context.solver->builtinTypes};
+    TypeId resultType = shallowClone(inputType, *arena, cloneState, /* ignorePersistent */ FFlag::LuauFreezeIgnorePersistent);
+
+    if (auto tableType = getMutable<TableType>(resultType))
+    {
+        tableType->scope = context.constraint->scope.get();
+    }
+
+    if (FFlag::LuauTrackInteriorFreeTypesOnScope)
+        trackInteriorFreeType(context.constraint->scope.get(), resultType);
+
+    TypePackId clonedTypePack = arena->addTypePack({resultType});
+    asMutable(context.result)->ty.emplace<BoundTypePack>(clonedTypePack);
+
+    return true;
+}
+
+static std::optional<TypeId> freezeTable(TypeId inputType, const MagicFunctionCallContext& context)
 {
     TypeArena* arena = context.solver->arena;
 
@@ -1383,7 +1476,7 @@ static std::optional<TypeId> freezeTable(TypeId inputType, MagicFunctionCallCont
     {
         // Clone the input type, this will become our final result type after we mutate it.
         CloneState cloneState{context.solver->builtinTypes};
-        TypeId resultType = shallowClone(inputType, *arena, cloneState);
+        TypeId resultType = shallowClone(inputType, *arena, cloneState, /* ignorePersistent */ FFlag::LuauFreezeIgnorePersistent);
         auto tableTy = getMutable<TableType>(resultType);
         // `clone` should not break this.
         LUAU_ASSERT(tableTy);
@@ -1408,10 +1501,13 @@ static std::optional<TypeId> freezeTable(TypeId inputType, MagicFunctionCallCont
     return std::nullopt;
 }
 
-static bool dcrMagicFunctionFreeze(MagicFunctionCallContext context)
+std::optional<WithPredicate<TypePackId>> MagicFreeze::handleOldSolver(struct TypeChecker &, const std::shared_ptr<struct Scope> &, const class AstExprCall &, WithPredicate<TypePackId>)
 {
-    LUAU_ASSERT(FFlag::LuauTypestateBuiltins2);
+    return std::nullopt;
+}
 
+bool MagicFreeze::infer(const MagicFunctionCallContext& context)
+{
     TypeArena* arena = context.solver->arena;
     const DataFlowGraph* dfg = context.solver->dfg.get();
     Scope* scope = context.constraint->scope.get();
@@ -1469,7 +1565,7 @@ static bool checkRequirePath(TypeChecker& typechecker, AstExpr* expr)
     return good;
 }
 
-static std::optional<WithPredicate<TypePackId>> magicFunctionRequire(
+std::optional<WithPredicate<TypePackId>> MagicRequire::handleOldSolver(
     TypeChecker& typechecker,
     const ScopePtr& scope,
     const AstExprCall& expr,
@@ -1515,7 +1611,7 @@ static bool checkRequirePathDcr(NotNull<ConstraintSolver> solver, AstExpr* expr)
     return good;
 }
 
-static bool dcrMagicFunctionRequire(MagicFunctionCallContext context)
+bool MagicRequire::infer(const MagicFunctionCallContext& context)
 {
     if (context.callSite->args.size != 1)
     {

Analysis/src/Clone.cpp

@@ -7,6 +7,7 @@
 #include "Luau/Unifiable.h"
 
 LUAU_FASTFLAG(LuauSolverV2)
+LUAU_FASTFLAG(LuauFreezeIgnorePersistent)
 
 // For each `Luau::clone` call, we will clone only up to N amount of types _and_ packs, as controlled by this limit.
 LUAU_FASTINTVARIABLE(LuauTypeCloneIterationLimit, 100'000)
@@ -38,14 +39,26 @@ class TypeCloner
     NotNull<SeenTypes> types;
     NotNull<SeenTypePacks> packs;
 
+    TypeId forceTy = nullptr;
+    TypePackId forceTp = nullptr;
+
     int steps = 0;
 
 public:
-    TypeCloner(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtinTypes, NotNull<SeenTypes> types, NotNull<SeenTypePacks> packs)
+    TypeCloner(
+        NotNull<TypeArena> arena,
+        NotNull<BuiltinTypes> builtinTypes,
+        NotNull<SeenTypes> types,
+        NotNull<SeenTypePacks> packs,
+        TypeId forceTy,
+        TypePackId forceTp
+    )
         : arena(arena)
         , builtinTypes(builtinTypes)
         , types(types)
         , packs(packs)
+        , forceTy(forceTy)
+        , forceTp(forceTp)
     {
     }
 
@@ -112,7 +125,7 @@ private:
         ty = follow(ty, FollowOption::DisableLazyTypeThunks);
         if (auto it = types->find(ty); it != types->end())
             return it->second;
-        else if (ty->persistent)
+        else if (ty->persistent && (!FFlag::LuauFreezeIgnorePersistent || ty != forceTy))
             return ty;
         return std::nullopt;
     }
@@ -122,7 +135,7 @@ private:
         tp = follow(tp);
         if (auto it = packs->find(tp); it != packs->end())
             return it->second;
-        else if (tp->persistent)
+        else if (tp->persistent && (!FFlag::LuauFreezeIgnorePersistent || tp != forceTp))
             return tp;
         return std::nullopt;
     }
@@ -148,7 +161,7 @@ public:
 
         if (auto clone = find(ty))
             return *clone;
-        else if (ty->persistent)
+        else if (ty->persistent && (!FFlag::LuauFreezeIgnorePersistent || ty != forceTy))
             return ty;
 
         TypeId target = arena->addType(ty->ty);
@@ -174,7 +187,7 @@ public:
 
         if (auto clone = find(tp))
             return *clone;
-        else if (tp->persistent)
+        else if (tp->persistent && (!FFlag::LuauFreezeIgnorePersistent || tp != forceTp))
             return tp;
 
         TypePackId target = arena->addTypePack(tp->ty);
@@ -458,21 +471,37 @@ private:
 
 } // namespace
 
-TypePackId shallowClone(TypePackId tp, TypeArena& dest, CloneState& cloneState)
+TypePackId shallowClone(TypePackId tp, TypeArena& dest, CloneState& cloneState, bool ignorePersistent)
 {
-    if (tp->persistent)
+    if (tp->persistent && (!FFlag::LuauFreezeIgnorePersistent || !ignorePersistent))
         return tp;
 
-    TypeCloner cloner{NotNull{&dest}, cloneState.builtinTypes, NotNull{&cloneState.seenTypes}, NotNull{&cloneState.seenTypePacks}};
+    TypeCloner cloner{
+        NotNull{&dest},
+        cloneState.builtinTypes,
+        NotNull{&cloneState.seenTypes},
+        NotNull{&cloneState.seenTypePacks},
+        nullptr,
+        FFlag::LuauFreezeIgnorePersistent && ignorePersistent ? tp : nullptr
+    };
+
     return cloner.shallowClone(tp);
 }
 
-TypeId shallowClone(TypeId typeId, TypeArena& dest, CloneState& cloneState)
+TypeId shallowClone(TypeId typeId, TypeArena& dest, CloneState& cloneState, bool ignorePersistent)
 {
-    if (typeId->persistent)
+    if (typeId->persistent && (!FFlag::LuauFreezeIgnorePersistent || !ignorePersistent))
         return typeId;
 
-    TypeCloner cloner{NotNull{&dest}, cloneState.builtinTypes, NotNull{&cloneState.seenTypes}, NotNull{&cloneState.seenTypePacks}};
+    TypeCloner cloner{
+        NotNull{&dest},
+        cloneState.builtinTypes,
+        NotNull{&cloneState.seenTypes},
+        NotNull{&cloneState.seenTypePacks},
+        FFlag::LuauFreezeIgnorePersistent && ignorePersistent ? typeId : nullptr,
+        nullptr
+    };
+
     return cloner.shallowClone(typeId);
 }
 
@@ -481,7 +510,7 @@ TypePackId clone(TypePackId tp, TypeArena& dest, CloneState& cloneState)
     if (tp->persistent)
         return tp;
 
-    TypeCloner cloner{NotNull{&dest}, cloneState.builtinTypes, NotNull{&cloneState.seenTypes}, NotNull{&cloneState.seenTypePacks}};
+    TypeCloner cloner{NotNull{&dest}, cloneState.builtinTypes, NotNull{&cloneState.seenTypes}, NotNull{&cloneState.seenTypePacks}, nullptr, nullptr};
     return cloner.clone(tp);
 }
 
@@ -490,13 +519,13 @@ TypeId clone(TypeId typeId, TypeArena& dest, CloneState& cloneState)
     if (typeId->persistent)
         return typeId;
 
-    TypeCloner cloner{NotNull{&dest}, cloneState.builtinTypes, NotNull{&cloneState.seenTypes}, NotNull{&cloneState.seenTypePacks}};
+    TypeCloner cloner{NotNull{&dest}, cloneState.builtinTypes, NotNull{&cloneState.seenTypes}, NotNull{&cloneState.seenTypePacks}, nullptr, nullptr};
     return cloner.clone(typeId);
 }
 
 TypeFun clone(const TypeFun& typeFun, TypeArena& dest, CloneState& cloneState)
 {
-    TypeCloner cloner{NotNull{&dest}, cloneState.builtinTypes, NotNull{&cloneState.seenTypes}, NotNull{&cloneState.seenTypePacks}};
+    TypeCloner cloner{NotNull{&dest}, cloneState.builtinTypes, NotNull{&cloneState.seenTypes}, NotNull{&cloneState.seenTypePacks}, nullptr, nullptr};
 
     TypeFun copy = typeFun;
 
@@ -521,4 +550,18 @@ TypeFun clone(const TypeFun& typeFun, TypeArena& dest, CloneState& cloneState)
     return copy;
 }
 
+Binding clone(const Binding& binding, TypeArena& dest, CloneState& cloneState)
+{
+    TypeCloner cloner{NotNull{&dest}, cloneState.builtinTypes, NotNull{&cloneState.seenTypes}, NotNull{&cloneState.seenTypePacks}, nullptr, nullptr};
+
+    Binding b;
+    b.deprecated = binding.deprecated;
+    b.deprecatedSuggestion = binding.deprecatedSuggestion;
+    b.documentationSymbol = binding.documentationSymbol;
+    b.location = binding.location;
+    b.typeId = cloner.clone(binding.typeId);
+
+    return b;
+}
+
 } // namespace Luau

Analysis/src/Constraint.cpp

@@ -3,8 +3,6 @@
 #include "Luau/Constraint.h"
 #include "Luau/VisitType.h"
 
-LUAU_FASTFLAGVARIABLE(LuauDontRefCountTypesInTypeFunctions)
-
 namespace Luau
 {
 
@@ -60,9 +58,8 @@ struct ReferenceCountInitializer : TypeOnceVisitor
         //
         // The default behavior here is `true` for "visit the child types"
         // of this type, hence:
-        return !FFlag::LuauDontRefCountTypesInTypeFunctions;
+        return false;
     }
-
 };
 
 bool isReferenceCountedType(const TypeId typ)

Analysis/src/ConstraintGenerator.cpp

@@ -31,13 +31,14 @@
 LUAU_FASTINT(LuauCheckRecursionLimit)
 LUAU_FASTFLAG(DebugLuauLogSolverToJson)
 LUAU_FASTFLAG(DebugLuauMagicTypes)
-LUAU_FASTFLAG(DebugLuauEqSatSimplification)
-LUAU_FASTFLAG(LuauTypestateBuiltins2)
+LUAU_FASTFLAG(LuauPreserveUnionIntersectionNodeForLeadingTokenSingleType)
 
-LUAU_FASTFLAGVARIABLE(LuauNewSolverVisitErrorExprLvalues)
 LUAU_FASTFLAGVARIABLE(LuauNewSolverPrePopulateClasses)
-LUAU_FASTFLAGVARIABLE(LuauUserTypeFunExportedAndLocal)
 LUAU_FASTFLAGVARIABLE(LuauNewSolverPopulateTableLocations)
+LUAU_FASTFLAGVARIABLE(LuauTrackInteriorFreeTypesOnScope)
+
+LUAU_FASTFLAGVARIABLE(InferGlobalTypes)
+LUAU_FASTFLAG(LuauFreeTypesMustHaveBounds)
 
 namespace Luau
 {
@@ -229,8 +230,17 @@ void ConstraintGenerator::visitModuleRoot(AstStatBlock* block)
     Checkpoint end = checkpoint(this);
 
     TypeId result = arena->addType(BlockedType{});
-    NotNull<Constraint> genConstraint =
-        addConstraint(scope, block->location, GeneralizationConstraint{result, moduleFnTy, std::move(interiorTypes.back())});
+    NotNull<Constraint> genConstraint = addConstraint(
+        scope,
+        block->location,
+        GeneralizationConstraint{
+            result, moduleFnTy, FFlag::LuauTrackInteriorFreeTypesOnScope ? std::vector<TypeId>{} : std::move(interiorTypes.back())
+        }
+    );
+
+    if (FFlag::LuauTrackInteriorFreeTypesOnScope)
+        scope->interiorFreeTypes = std::move(interiorTypes.back());
+
     getMutable<BlockedType>(result)->setOwner(genConstraint);
     forEachConstraint(
         start,
@@ -299,9 +309,19 @@ void ConstraintGenerator::visitFragmentRoot(const ScopePtr& resumeScope, AstStat
     }
 }
 
+
 TypeId ConstraintGenerator::freshType(const ScopePtr& scope)
 {
-    return Luau::freshType(arena, builtinTypes, scope.get());
+    if (FFlag::LuauTrackInteriorFreeTypesOnScope)
+    {
+        auto ft = Luau::freshType(arena, builtinTypes, scope.get());
+        interiorTypes.back().push_back(ft);
+        return ft;
+    }
+    else
+    {
+        return Luau::freshType(arena, builtinTypes, scope.get());
+    }
 }
 
 TypePackId ConstraintGenerator::freshTypePack(const ScopePtr& scope)
@@ -720,12 +740,6 @@ void ConstraintGenerator::checkAliases(const ScopePtr& scope, AstStatBlock* bloc
                 continue;
             }
 
-            if (!FFlag::LuauUserTypeFunExportedAndLocal && scope->parent != globalScope)
-            {
-                reportError(function->location, GenericError{"Local user-defined functions are not supported yet"});
-                continue;
-            }
-
             ScopePtr defnScope = childScope(function, scope);
 
             // Create TypeFunctionInstanceType
@@ -751,11 +765,8 @@ void ConstraintGenerator::checkAliases(const ScopePtr& scope, AstStatBlock* bloc
 
             UserDefinedFunctionData udtfData;
 
-            if (FFlag::LuauUserTypeFunExportedAndLocal)
-            {
-                udtfData.owner = module;
-                udtfData.definition = function;
-            }
+            udtfData.owner = module;
+            udtfData.definition = function;
 
             TypeId typeFunctionTy = arena->addType(
                 TypeFunctionInstanceType{NotNull{&builtinTypeFunctions().userFunc}, std::move(typeParams), {}, function->name, udtfData}
@@ -764,7 +775,7 @@ void ConstraintGenerator::checkAliases(const ScopePtr& scope, AstStatBlock* bloc
             TypeFun typeFunction{std::move(quantifiedTypeParams), typeFunctionTy};
 
             // Set type bindings and definition locations for this user-defined type function
-            if (FFlag::LuauUserTypeFunExportedAndLocal && function->exported)
+            if (function->exported)
                 scope->exportedTypeBindings[function->name.value] = std::move(typeFunction);
             else
                 scope->privateTypeBindings[function->name.value] = std::move(typeFunction);
@@ -799,49 +810,74 @@ void ConstraintGenerator::checkAliases(const ScopePtr& scope, AstStatBlock* bloc
         }
     }
 
-    if (FFlag::LuauUserTypeFunExportedAndLocal)
+    // Additional pass for user-defined type functions to fill in their environments completely
+    for (AstStat* stat : block->body)
     {
-        // Additional pass for user-defined type functions to fill in their environments completely
-        for (AstStat* stat : block->body)
+        if (auto function = stat->as<AstStatTypeFunction>())
         {
-            if (auto function = stat->as<AstStatTypeFunction>())
+            // Find the type function we have already created
+            TypeFunctionInstanceType* mainTypeFun = nullptr;
+
+            if (auto it = scope->privateTypeBindings.find(function->name.value); it != scope->privateTypeBindings.end())
+                mainTypeFun = getMutable<TypeFunctionInstanceType>(it->second.type);
+
+            if (!mainTypeFun)
             {
-                // Find the type function we have already created
-                TypeFunctionInstanceType* mainTypeFun = nullptr;
-
-                if (auto it = scope->privateTypeBindings.find(function->name.value); it != scope->privateTypeBindings.end())
+                if (auto it = scope->exportedTypeBindings.find(function->name.value); it != scope->exportedTypeBindings.end())
                     mainTypeFun = getMutable<TypeFunctionInstanceType>(it->second.type);
+            }
 
-                if (!mainTypeFun)
+            // Fill it with all visible type functions
+            if (mainTypeFun)
+            {
+                UserDefinedFunctionData& userFuncData = mainTypeFun->userFuncData;
+                size_t level = 0;
+
+                for (Scope* curr = scope.get(); curr; curr = curr->parent.get())
                 {
-                    if (auto it = scope->exportedTypeBindings.find(function->name.value); it != scope->exportedTypeBindings.end())
-                        mainTypeFun = getMutable<TypeFunctionInstanceType>(it->second.type);
-                }
-
-                // Fill it with all visible type functions
-                if (mainTypeFun)
-                {
-                    UserDefinedFunctionData& userFuncData = mainTypeFun->userFuncData;
-
-                    for (Scope* curr = scope.get(); curr; curr = curr->parent.get())
+                    for (auto& [name, tf] : curr->privateTypeBindings)
                     {
-                        for (auto& [name, tf] : curr->privateTypeBindings)
-                        {
-                            if (userFuncData.environment.find(name))
-                                continue;
+                        if (userFuncData.environment.find(name))
+                            continue;
 
-                            if (auto ty = get<TypeFunctionInstanceType>(tf.type); ty && ty->userFuncData.definition)
-                                userFuncData.environment[name] = ty->userFuncData.definition;
-                        }
+                        if (auto ty = get<TypeFunctionInstanceType>(tf.type); ty && ty->userFuncData.definition)
+                            userFuncData.environment[name] = std::make_pair(ty->userFuncData.definition, level);
+                    }
 
-                        for (auto& [name, tf] : curr->exportedTypeBindings)
-                        {
-                            if (userFuncData.environment.find(name))
-                                continue;
+                    for (auto& [name, tf] : curr->exportedTypeBindings)
+                    {
+                        if (userFuncData.environment.find(name))
+                            continue;
 
-                            if (auto ty = get<TypeFunctionInstanceType>(tf.type); ty && ty->userFuncData.definition)
-                                userFuncData.environment[name] = ty->userFuncData.definition;
-                        }
+                        if (auto ty = get<TypeFunctionInstanceType>(tf.type); ty && ty->userFuncData.definition)
+                            userFuncData.environment[name] = std::make_pair(ty->userFuncData.definition, level);
+                    }
+
+                    level++;
+                }
+            }
+            else if (mainTypeFun)
+            {
+                UserDefinedFunctionData& userFuncData = mainTypeFun->userFuncData;
+
+                for (Scope* curr = scope.get(); curr; curr = curr->parent.get())
+                {
+                    for (auto& [name, tf] : curr->privateTypeBindings)
+                    {
+                        if (userFuncData.environment_DEPRECATED.find(name))
+                            continue;
+
+                        if (auto ty = get<TypeFunctionInstanceType>(tf.type); ty && ty->userFuncData.definition)
+                            userFuncData.environment_DEPRECATED[name] = ty->userFuncData.definition;
+                    }
+
+                    for (auto& [name, tf] : curr->exportedTypeBindings)
+                    {
+                        if (userFuncData.environment_DEPRECATED.find(name))
+                            continue;
+
+                        if (auto ty = get<TypeFunctionInstanceType>(tf.type); ty && ty->userFuncData.definition)
+                            userFuncData.environment_DEPRECATED[name] = ty->userFuncData.definition;
                     }
                 }
             }
@@ -1053,18 +1089,8 @@ ControlFlow ConstraintGenerator::visit(const ScopePtr& scope, AstStatLocal* stat
             addConstraint(scope, value->location, NameConstraint{*firstValueType, var->name.value, /*synthetic*/ true});
         else if (const AstExprCall* call = value->as<AstExprCall>())
         {
-            if (FFlag::LuauTypestateBuiltins2)
-            {
-                if (matchSetMetatable(*call))
-                    addConstraint(scope, value->location, NameConstraint{*firstValueType, var->name.value, /*synthetic*/ true});
-            }
-            else
-            {
-                if (const AstExprGlobal* global = call->func->as<AstExprGlobal>(); global && global->name == "setmetatable")
-                {
-                    addConstraint(scope, value->location, NameConstraint{*firstValueType, var->name.value, /*synthetic*/ true});
-                }
-            }
+            if (matchSetMetatable(*call))
+                addConstraint(scope, value->location, NameConstraint{*firstValueType, var->name.value, /*synthetic*/ true});
         }
     }
 
@@ -1571,20 +1597,6 @@ ControlFlow ConstraintGenerator::visit(const ScopePtr& scope, AstStatTypeAlias*
 
 ControlFlow ConstraintGenerator::visit(const ScopePtr& scope, AstStatTypeFunction* function)
 {
-    // If a type function with the same name was already defined, we skip over
-    auto bindingIt = scope->privateTypeBindings.find(function->name.value);
-    if (bindingIt == scope->privateTypeBindings.end())
-        return ControlFlow::None;
-
-    TypeFun typeFunction = bindingIt->second;
-
-    // Adding typeAliasExpansionConstraint on user-defined type function for the constraint solver
-    if (auto typeFunctionTy = get<TypeFunctionInstanceType>(follow(typeFunction.type)))
-    {
-        TypeId expansionTy = arena->addType(PendingExpansionType{{}, function->name, typeFunctionTy->typeArguments, typeFunctionTy->packArguments});
-        addConstraint(scope, function->location, TypeAliasExpansionConstraint{/* target */ expansionTy});
-    }
-
     return ControlFlow::None;
 }
 
@@ -2047,7 +2059,7 @@ InferencePack ConstraintGenerator::checkPack(const ScopePtr& scope, AstExprCall*
         return InferencePack{arena->addTypePack({resultTy}), {refinementArena.variadic(returnRefinements)}};
     }
 
-    if (FFlag::LuauTypestateBuiltins2 && shouldTypestateForFirstArgument(*call) && call->args.size > 0 && isLValue(call->args.data[0]))
+    if (shouldTypestateForFirstArgument(*call) && call->args.size > 0 && isLValue(call->args.data[0]))
     {
         AstExpr* targetExpr = call->args.data[0];
         auto resultTy = arena->addType(BlockedType{});
@@ -2196,7 +2208,8 @@ Inference ConstraintGenerator::check(const ScopePtr& scope, AstExprConstantStrin
     if (forceSingleton)
         return Inference{arena->addType(SingletonType{StringSingleton{std::string{string->value.data, string->value.size}}})};
 
-    FreeType ft = FreeType{scope.get()};
+    FreeType ft =
+        FFlag::LuauFreeTypesMustHaveBounds ? FreeType{scope.get(), builtinTypes->neverType, builtinTypes->unknownType} : FreeType{scope.get()};
     ft.lowerBound = arena->addType(SingletonType{StringSingleton{std::string{string->value.data, string->value.size}}});
     ft.upperBound = builtinTypes->stringType;
     const TypeId freeTy = arena->addType(ft);
@@ -2210,7 +2223,8 @@ Inference ConstraintGenerator::check(const ScopePtr& scope, AstExprConstantBool*
     if (forceSingleton)
         return Inference{singletonType};
 
-    FreeType ft = FreeType{scope.get()};
+    FreeType ft =
+        FFlag::LuauFreeTypesMustHaveBounds ? FreeType{scope.get(), builtinTypes->neverType, builtinTypes->unknownType} : FreeType{scope.get()};
     ft.lowerBound = singletonType;
     ft.upperBound = builtinTypes->booleanType;
     const TypeId freeTy = arena->addType(ft);
@@ -2372,8 +2386,17 @@ Inference ConstraintGenerator::check(const ScopePtr& scope, AstExprFunction* fun
     Checkpoint endCheckpoint = checkpoint(this);
 
     TypeId generalizedTy = arena->addType(BlockedType{});
-    NotNull<Constraint> gc =
-        addConstraint(sig.signatureScope, func->location, GeneralizationConstraint{generalizedTy, sig.signature, std::move(interiorTypes.back())});
+    NotNull<Constraint> gc = addConstraint(
+        sig.signatureScope,
+        func->location,
+        GeneralizationConstraint{
+            generalizedTy, sig.signature, FFlag::LuauTrackInteriorFreeTypesOnScope ? std::vector<TypeId>{} : std::move(interiorTypes.back())
+        }
+    );
+
+    if (FFlag::LuauTrackInteriorFreeTypesOnScope)
+        sig.signatureScope->interiorFreeTypes = std::move(interiorTypes.back());
+
     getMutable<BlockedType>(generalizedTy)->setOwner(gc);
     interiorTypes.pop_back();
 
@@ -2721,15 +2744,12 @@ void ConstraintGenerator::visitLValue(const ScopePtr& scope, AstExpr* expr, Type
         visitLValue(scope, e, rhsType);
     else if (auto e = expr->as<AstExprError>())
     {
-        if (FFlag::LuauNewSolverVisitErrorExprLvalues)
+        // If we end up with some sort of error expression in an lvalue
+        // position, at least go and check the expressions so that when
+        // we visit them later, there aren't any invalid assumptions.
+        for (auto subExpr : e->expressions)
         {
-            // If we end up with some sort of error expression in an lvalue
-            // position, at least go and check the expressions so that when
-            // we visit them later, there aren't any invalid assumptions.
-            for (auto subExpr : e->expressions)
-            {
-                check(scope, subExpr);
-            }
+            check(scope, subExpr);
         }
     }
     else
@@ -2790,6 +2810,14 @@ void ConstraintGenerator::visitLValue(const ScopePtr& scope, AstExprGlobal* glob
         DefId def = dfg->getDef(global);
         rootScope->lvalueTypes[def] = rhsType;
 
+        if (FFlag::InferGlobalTypes)
+        {
+            // Sketchy: We're specifically looking for BlockedTypes that were
+            // initially created by ConstraintGenerator::prepopulateGlobalScope.
+            if (auto bt = get<BlockedType>(follow(*annotatedTy)); bt && !bt->getOwner())
+                emplaceType<BoundType>(asMutable(*annotatedTy), rhsType);
+        }
+
         addConstraint(scope, global->location, SubtypeConstraint{rhsType, *annotatedTy});
     }
 }
@@ -2931,11 +2959,11 @@ Inference ConstraintGenerator::check(const ScopePtr& scope, AstExprTable* expr,
                 ty,
                 expr,
                 toBlock
-                );
-                // The visitor we ran prior should ensure that there are no
-                // blocked types that we would encounter while matching on
-                // this expression.
-                LUAU_ASSERT(toBlock.empty());
+            );
+            // The visitor we ran prior should ensure that there are no
+            // blocked types that we would encounter while matching on
+            // this expression.
+            LUAU_ASSERT(toBlock.empty());
         }
     }
 
@@ -3182,9 +3210,8 @@ TypeId ConstraintGenerator::resolveReferenceType(
 
     if (alias.has_value())
     {
-        // If the alias is not generic, we don't need to set up a blocked
-        // type and an instantiation constraint.
-        if (alias.has_value() && alias->typeParams.empty() && alias->typePackParams.empty())
+        // If the alias is not generic, we don't need to set up a blocked type and an instantiation constraint
+        if (alias.has_value() && alias->typeParams.empty() && alias->typePackParams.empty() && !ref->hasParameterList)
         {
             result = alias->type;
         }
@@ -3393,6 +3420,12 @@ TypeId ConstraintGenerator::resolveType(const ScopePtr& scope, AstType* ty, bool
     }
     else if (auto unionAnnotation = ty->as<AstTypeUnion>())
     {
+        if (FFlag::LuauPreserveUnionIntersectionNodeForLeadingTokenSingleType)
+        {
+            if (unionAnnotation->types.size == 1)
+                return resolveType(scope, unionAnnotation->types.data[0], inTypeArguments);
+        }
+
         std::vector<TypeId> parts;
         for (AstType* part : unionAnnotation->types)
         {
@@ -3403,6 +3436,12 @@ TypeId ConstraintGenerator::resolveType(const ScopePtr& scope, AstType* ty, bool
     }
     else if (auto intersectionAnnotation = ty->as<AstTypeIntersection>())
     {
+        if (FFlag::LuauPreserveUnionIntersectionNodeForLeadingTokenSingleType)
+        {
+            if (intersectionAnnotation->types.size == 1)
+                return resolveType(scope, intersectionAnnotation->types.data[0], inTypeArguments);
+        }
+
         std::vector<TypeId> parts;
         for (AstType* part : intersectionAnnotation->types)
         {
@@ -3411,6 +3450,10 @@ TypeId ConstraintGenerator::resolveType(const ScopePtr& scope, AstType* ty, bool
 
         result = arena->addType(IntersectionType{parts});
     }
+    else if (auto typeGroupAnnotation = ty->as<AstTypeGroup>())
+    {
+        result = resolveType(scope, typeGroupAnnotation->type, inTypeArguments);
+    }
     else if (auto boolAnnotation = ty->as<AstTypeSingletonBool>())
     {
         if (boolAnnotation->value)
@@ -3694,6 +3737,26 @@ struct GlobalPrepopulator : AstVisitor
         return true;
     }
 
+    bool visit(AstStatAssign* assign) override
+    {
+        if (FFlag::InferGlobalTypes)
+        {
+            for (const Luau::AstExpr* expr : assign->vars)
+            {
+                if (const AstExprGlobal* g = expr->as<AstExprGlobal>())
+                {
+                    if (!globalScope->lookup(g->name))
+                        globalScope->globalsToWarn.insert(g->name.value);
+
+                    TypeId bt = arena->addType(BlockedType{});
+                    globalScope->bindings[g->name] = Binding{bt, g->location};
+                }
+            }
+        }
+
+        return true;
+    }
+
     bool visit(AstStatFunction* function) override
     {
         if (AstExprGlobal* g = function->name->as<AstExprGlobal>())
@@ -3877,20 +3940,7 @@ TypeId ConstraintGenerator::createTypeFunctionInstance(
 
 TypeId ConstraintGenerator::simplifyUnion(const ScopePtr& scope, Location location, TypeId left, TypeId right)
 {
-    if (FFlag::DebugLuauEqSatSimplification)
-    {
-        TypeId ty = arena->addType(UnionType{{left, right}});
-        std::optional<EqSatSimplificationResult> res = eqSatSimplify(simplifier, ty);
-        if (!res)
-            return ty;
-
-        for (TypeId tyFun : res->newTypeFunctions)
-            addConstraint(scope, location, ReduceConstraint{tyFun});
-
-        return res->result;
-    }
-    else
-        return ::Luau::simplifyUnion(builtinTypes, arena, left, right).result;
+    return ::Luau::simplifyUnion(builtinTypes, arena, left, right).result;
 }
 
 std::vector<NotNull<Constraint>> borrowConstraints(const std::vector<ConstraintPtr>& constraints)

Analysis/src/ConstraintSolver.cpp

@@ -31,10 +31,12 @@ LUAU_FASTFLAGVARIABLE(DebugLuauLogSolver)
 LUAU_FASTFLAGVARIABLE(DebugLuauLogSolverIncludeDependencies)
 LUAU_FASTFLAGVARIABLE(DebugLuauLogBindings)
 LUAU_FASTINTVARIABLE(LuauSolverRecursionLimit, 500)
-LUAU_FASTFLAGVARIABLE(LuauRemoveNotAnyHack)
 LUAU_FASTFLAGVARIABLE(DebugLuauEqSatSimplification)
 LUAU_FASTFLAG(LuauNewSolverPopulateTableLocations)
 LUAU_FASTFLAGVARIABLE(LuauAllowNilAssignmentToIndexer)
+LUAU_FASTFLAG(LuauTrackInteriorFreeTypesOnScope)
+LUAU_FASTFLAGVARIABLE(LuauAlwaysFillInFunctionCallDiscriminantTypes)
+LUAU_FASTFLAGVARIABLE(LuauTrackInteriorFreeTablesOnScope)
 
 namespace Luau
 {
@@ -72,7 +74,7 @@ size_t HashBlockedConstraintId::operator()(const BlockedConstraintId& bci) const
 {
     if (auto blocked = get<BlockedType>(ty))
     {
-        Constraint* owner = blocked->getOwner();
+        const Constraint* owner = blocked->getOwner();
         LUAU_ASSERT(owner);
         return owner == constraint;
     }
@@ -443,7 +445,7 @@ void ConstraintSolver::run()
             if (success)
             {
                 unblock(c);
-                unsolvedConstraints.erase(unsolvedConstraints.begin() + i);
+                unsolvedConstraints.erase(unsolvedConstraints.begin() + ptrdiff_t(i));
 
                 // decrement the referenced free types for this constraint if we dispatched successfully!
                 for (auto ty : c->getMaybeMutatedFreeTypes())
@@ -550,7 +552,7 @@ void ConstraintSolver::finalizeTypeFunctions()
     }
 }
 
-bool ConstraintSolver::isDone()
+bool ConstraintSolver::isDone() const
 {
     return unsolvedConstraints.empty();
 }
@@ -723,8 +725,20 @@ bool ConstraintSolver::tryDispatch(const GeneralizationConstraint& c, NotNull<co
         bind(constraint, c.generalizedType, builtinTypes->errorRecoveryType());
     }
 
-    for (TypeId ty : c.interiorTypes)
-        generalize(NotNull{arena}, builtinTypes, constraint->scope, generalizedTypes, ty, /* avoidSealingTables */ false);
+    if (FFlag::LuauTrackInteriorFreeTypesOnScope)
+    {
+        // We check if this member is initialized and then access it, but
+        // clang-tidy doesn't understand this is safe.
+        if (constraint->scope->interiorFreeTypes)
+            for (TypeId ty : *constraint->scope->interiorFreeTypes) // NOLINT(bugprone-unchecked-optional-access)
+                generalize(NotNull{arena}, builtinTypes, constraint->scope, generalizedTypes, ty, /* avoidSealingTables */ false);
+    }
+    else
+    {
+        for (TypeId ty : c.interiorTypes)
+            generalize(NotNull{arena}, builtinTypes, constraint->scope, generalizedTypes, ty, /* avoidSealingTables */ false);
+    }
+
 
     return true;
 }
@@ -800,9 +814,17 @@ bool ConstraintSolver::tryDispatch(const IterableConstraint& c, NotNull<const Co
     {
         TypeId keyTy = freshType(arena, builtinTypes, constraint->scope);
         TypeId valueTy = freshType(arena, builtinTypes, constraint->scope);
+        if (FFlag::LuauTrackInteriorFreeTypesOnScope)
+        {
+            trackInteriorFreeType(constraint->scope, keyTy);
+            trackInteriorFreeType(constraint->scope, valueTy);
+        }
         TypeId tableTy =
             arena->addType(TableType{TableType::Props{}, TableIndexer{keyTy, valueTy}, TypeLevel{}, constraint->scope, TableState::Free});
 
+        if (FFlag::LuauTrackInteriorFreeTypesOnScope && FFlag::LuauTrackInteriorFreeTablesOnScope)
+            trackInteriorFreeType(constraint->scope, tableTy);
+
         unify(constraint, nextTy, tableTy);
 
         auto it = begin(c.variables);
@@ -939,14 +961,6 @@ bool ConstraintSolver::tryDispatch(const TypeAliasExpansionConstraint& c, NotNul
     if (auto typeFn = get<TypeFunctionInstanceType>(follow(tf->type)))
         pushConstraint(NotNull(constraint->scope.get()), constraint->location, ReduceConstraint{tf->type});
 
-    // If there are no parameters to the type function we can just use the type
-    // directly.
-    if (tf->typeParams.empty() && tf->typePackParams.empty())
-    {
-        bindResult(tf->type);
-        return true;
-    }
-
     // Due to how pending expansion types and TypeFun's are created
     // If this check passes, we have created a cyclic / corecursive type alias
     // of size 0
@@ -959,6 +973,13 @@ bool ConstraintSolver::tryDispatch(const TypeAliasExpansionConstraint& c, NotNul
         return true;
     }
 
+    // If there are no parameters to the type function we can just use the type directly
+    if (tf->typeParams.empty() && tf->typePackParams.empty())
+    {
+        bindResult(tf->type);
+        return true;
+    }
+
     auto [typeArguments, packArguments] = saturateArguments(arena, builtinTypes, *tf, petv->typeArguments, petv->packArguments);
 
     bool sameTypes = std::equal(
@@ -1122,6 +1143,28 @@ bool ConstraintSolver::tryDispatch(const TypeAliasExpansionConstraint& c, NotNul
     return true;
 }
 
+void ConstraintSolver::fillInDiscriminantTypes(
+    NotNull<const Constraint> constraint,
+    const std::vector<std::optional<TypeId>>& discriminantTypes
+)
+{
+    for (std::optional<TypeId> ty : discriminantTypes)
+    {
+        if (!ty)
+            continue;
+
+        // If the discriminant type has been transmuted, we need to unblock them.
+        if (!isBlocked(*ty))
+        {
+            unblock(*ty, constraint->location);
+            continue;
+        }
+
+        // We bind any unused discriminants to the `*no-refine*` type indicating that it can be safely ignored.
+        emplaceType<BoundType>(asMutable(follow(*ty)), builtinTypes->noRefineType);
+    }
+}
+
 bool ConstraintSolver::tryDispatch(const FunctionCallConstraint& c, NotNull<const Constraint> constraint)
 {
     TypeId fn = follow(c.fn);
@@ -1137,6 +1180,8 @@ bool ConstraintSolver::tryDispatch(const FunctionCallConstraint& c, NotNull<cons
     {
         emplaceTypePack<BoundTypePack>(asMutable(c.result), builtinTypes->anyTypePack);
         unblock(c.result, constraint->location);
+        if (FFlag::LuauAlwaysFillInFunctionCallDiscriminantTypes)
+            fillInDiscriminantTypes(constraint, c.discriminantTypes);
         return true;
     }
 
@@ -1144,12 +1189,16 @@ bool ConstraintSolver::tryDispatch(const FunctionCallConstraint& c, NotNull<cons
     if (get<ErrorType>(fn))
     {
         bind(constraint, c.result, builtinTypes->errorRecoveryTypePack());
+        if (FFlag::LuauAlwaysFillInFunctionCallDiscriminantTypes)
+            fillInDiscriminantTypes(constraint, c.discriminantTypes);
         return true;
     }
 
     if (get<NeverType>(fn))
     {
         bind(constraint, c.result, builtinTypes->neverTypePack);
+        if (FFlag::LuauAlwaysFillInFunctionCallDiscriminantTypes)
+            fillInDiscriminantTypes(constraint, c.discriminantTypes);
         return true;
     }
 
@@ -1219,50 +1268,46 @@ bool ConstraintSolver::tryDispatch(const FunctionCallConstraint& c, NotNull<cons
 
         if (ftv)
         {
-            if (ftv->dcrMagicFunction)
-                usedMagic = ftv->dcrMagicFunction(MagicFunctionCallContext{NotNull{this}, constraint, c.callSite, c.argsPack, result});
-
-            if (ftv->dcrMagicRefinement)
-                ftv->dcrMagicRefinement(MagicRefinementContext{constraint->scope, c.callSite, c.discriminantTypes});
+            if (ftv->magic)
+            {
+                usedMagic = ftv->magic->infer(MagicFunctionCallContext{NotNull{this}, constraint, c.callSite, c.argsPack, result});
+                ftv->magic->refine(MagicRefinementContext{constraint->scope, c.callSite, c.discriminantTypes});
+            }
         }
 
         if (!usedMagic)
             emplace<FreeTypePack>(constraint, c.result, constraint->scope);
     }
 
-    for (std::optional<TypeId> ty : c.discriminantTypes)
+    if (FFlag::LuauAlwaysFillInFunctionCallDiscriminantTypes)
     {
-        if (!ty)
-            continue;
-
-        // If the discriminant type has been transmuted, we need to unblock them.
-        if (!isBlocked(*ty))
+        fillInDiscriminantTypes(constraint, c.discriminantTypes);
+    }
+    else
+    {
+        // NOTE: This is the body of the `fillInDiscriminantTypes` helper.
+        for (std::optional<TypeId> ty : c.discriminantTypes)
         {
-            unblock(*ty, constraint->location);
-            continue;
-        }
+            if (!ty)
+                continue;
+
+            // If the discriminant type has been transmuted, we need to unblock them.
+            if (!isBlocked(*ty))
+            {
+                unblock(*ty, constraint->location);
+                continue;
+            }
 
-        if (FFlag::LuauRemoveNotAnyHack)
-        {
             // We bind any unused discriminants to the `*no-refine*` type indicating that it can be safely ignored.
             emplaceType<BoundType>(asMutable(follow(*ty)), builtinTypes->noRefineType);
         }
-        else
-        {
-            // We use `any` here because the discriminant type may be pointed at by both branches,
-            // where the discriminant type is not negated, and the other where it is negated, i.e.
-            // `unknown ~ unknown` and `~unknown ~ never`, so `T & unknown ~ T` and `T & ~unknown ~ never`
-            // v.s.
-            // `any ~ any` and `~any ~ any`, so `T & any ~ T` and `T & ~any ~ T`
-            //
-            // In practice, users cannot negate `any`, so this is an implementation detail we can always change.
-            emplaceType<BoundType>(asMutable(follow(*ty)), builtinTypes->anyType);
-        }
     }
 
+
     OverloadResolver resolver{
         builtinTypes,
         NotNull{arena},
+        simplifier,
         normalizer,
         typeFunctionRuntime,
         constraint->scope,
@@ -1618,7 +1663,7 @@ bool ConstraintSolver::tryDispatchHasIndexer(
         for (TypeId part : parts)
         {
             TypeId r = arena->addType(BlockedType{});
-            getMutable<BlockedType>(r)->setOwner(const_cast<Constraint*>(constraint.get()));
+            getMutable<BlockedType>(r)->setOwner(constraint.get());
 
             bool ok = tryDispatchHasIndexer(recursionDepth, constraint, part, indexType, r, seen);
             // If we've cut a recursive loop short, skip it.
@@ -1650,7 +1695,7 @@ bool ConstraintSolver::tryDispatchHasIndexer(
         for (TypeId part : parts)
         {
             TypeId r = arena->addType(BlockedType{});
-            getMutable<BlockedType>(r)->setOwner(const_cast<Constraint*>(constraint.get()));
+            getMutable<BlockedType>(r)->setOwner(constraint.get());
 
             bool ok = tryDispatchHasIndexer(recursionDepth, constraint, part, indexType, r, seen);
             // If we've cut a recursive loop short, skip it.
@@ -1770,6 +1815,10 @@ bool ConstraintSolver::tryDispatch(const AssignPropConstraint& c, NotNull<const
         else
         {
             TypeId newUpperBound = arena->addType(TableType{TableState::Free, TypeLevel{}, constraint->scope});
+
+            if (FFlag::LuauTrackInteriorFreeTypesOnScope && FFlag::LuauTrackInteriorFreeTablesOnScope)
+                trackInteriorFreeType(constraint->scope, newUpperBound);
+
             TableType* upperTable = getMutable<TableType>(newUpperBound);
             LUAU_ASSERT(upperTable);
 
@@ -2048,6 +2097,8 @@ bool ConstraintSolver::tryDispatch(const UnpackConstraint& c, NotNull<const Cons
                 // constitute any meaningful constraint, so we replace it
                 // with a free type.
                 TypeId f = freshType(arena, builtinTypes, constraint->scope);
+                if (FFlag::LuauTrackInteriorFreeTypesOnScope)
+                    trackInteriorFreeType(constraint->scope, f);
                 shiftReferences(resultTy, f);
                 emplaceType<BoundType>(asMutable(resultTy), f);
             }
@@ -2103,6 +2154,11 @@ bool ConstraintSolver::tryDispatch(const ReduceConstraint& c, NotNull<const Cons
 
     if (force || reductionFinished)
     {
+        for (auto& message : result.messages)
+        {
+            reportError(std::move(message));
+        }
+
         // if we're completely dispatching this constraint, we want to record any uninhabited type functions to unblock.
         for (auto error : result.errors)
         {
@@ -2178,6 +2234,11 @@ bool ConstraintSolver::tryDispatchIterableTable(TypeId iteratorTy, const Iterabl
     {
         TypeId keyTy = freshType(arena, builtinTypes, constraint->scope);
         TypeId valueTy = freshType(arena, builtinTypes, constraint->scope);
+        if (FFlag::LuauTrackInteriorFreeTypesOnScope)
+        {
+            trackInteriorFreeType(constraint->scope, keyTy);
+            trackInteriorFreeType(constraint->scope, valueTy);
+        }
         TypeId tableTy = arena->addType(TableType{TableState::Sealed, {}, constraint->scope});
         getMutable<TableType>(tableTy)->indexer = TableIndexer{keyTy, valueTy};
 
@@ -2434,6 +2495,8 @@ TablePropLookupResult ConstraintSolver::lookupTableProp(
         if (ttv->state == TableState::Free)
         {
             TypeId result = freshType(arena, builtinTypes, ttv->scope);
+            if (FFlag::LuauTrackInteriorFreeTypesOnScope)
+                trackInteriorFreeType(ttv->scope, result);
             switch (context)
             {
             case ValueContext::RValue:
@@ -2539,10 +2602,17 @@ TablePropLookupResult ConstraintSolver::lookupTableProp(
         NotNull<Scope> scope{ft->scope};
 
         const TypeId newUpperBound = arena->addType(TableType{TableState::Free, TypeLevel{}, scope});
+
+        if (FFlag::LuauTrackInteriorFreeTypesOnScope && FFlag::LuauTrackInteriorFreeTablesOnScope)
+            trackInteriorFreeType(constraint->scope, newUpperBound);
+
         TableType* tt = getMutable<TableType>(newUpperBound);
         LUAU_ASSERT(tt);
         TypeId propType = freshType(arena, builtinTypes, scope);
 
+        if (FFlag::LuauTrackInteriorFreeTypesOnScope)
+            trackInteriorFreeType(scope, propType);
+
         switch (context)
         {
         case ValueContext::RValue:
@@ -2773,10 +2843,10 @@ bool ConstraintSolver::blockOnPendingTypes(TypeId target, NotNull<const Constrai
     return !blocker.blocked;
 }
 
-bool ConstraintSolver::blockOnPendingTypes(TypePackId pack, NotNull<const Constraint> constraint)
+bool ConstraintSolver::blockOnPendingTypes(TypePackId targetPack, NotNull<const Constraint> constraint)
 {
     Blocker blocker{NotNull{this}, constraint};
-    blocker.traverse(pack);
+    blocker.traverse(targetPack);
     return !blocker.blocked;
 }
 

Analysis/src/DataFlowGraph.cpp

@@ -13,7 +13,6 @@
 
 LUAU_FASTFLAG(DebugLuauFreezeArena)
 LUAU_FASTFLAG(LuauSolverV2)
-LUAU_FASTFLAG(LuauTypestateBuiltins2)
 
 namespace Luau
 {
@@ -62,6 +61,12 @@ const RefinementKey* RefinementKeyArena::node(const RefinementKey* parent, DefId
     return allocator.allocate(RefinementKey{parent, def, propName});
 }
 
+DataFlowGraph::DataFlowGraph(NotNull<DefArena> defArena, NotNull<RefinementKeyArena> keyArena)
+    : defArena{defArena}
+    , keyArena{keyArena}
+{
+}
+
 DefId DataFlowGraph::getDef(const AstExpr* expr) const
 {
     auto def = astDefs.find(expr);
@@ -178,11 +183,23 @@ bool DfgScope::canUpdateDefinition(DefId def, const std::string& key) const
     return true;
 }
 
-DataFlowGraph DataFlowGraphBuilder::build(AstStatBlock* block, NotNull<InternalErrorReporter> handle)
+DataFlowGraphBuilder::DataFlowGraphBuilder(NotNull<DefArena> defArena, NotNull<RefinementKeyArena> keyArena)
+    : graph{defArena, keyArena}
+    , defArena{defArena}
+    , keyArena{keyArena}
+{
+}
+
+DataFlowGraph DataFlowGraphBuilder::build(
+    AstStatBlock* block,
+    NotNull<DefArena> defArena,
+    NotNull<RefinementKeyArena> keyArena,
+    NotNull<struct InternalErrorReporter> handle
+)
 {
     LUAU_TIMETRACE_SCOPE("DataFlowGraphBuilder::build", "Typechecking");
 
-    DataFlowGraphBuilder builder;
+    DataFlowGraphBuilder builder(defArena, keyArena);
     builder.handle = handle;
     DfgScope* moduleScope = builder.makeChildScope();
     PushScope ps{builder.scopeStack, moduleScope};
@@ -198,30 +215,6 @@ DataFlowGraph DataFlowGraphBuilder::build(AstStatBlock* block, NotNull<InternalE
     return std::move(builder.graph);
 }
 
-std::pair<std::shared_ptr<DataFlowGraph>, std::vector<std::unique_ptr<DfgScope>>> DataFlowGraphBuilder::buildShared(
-    AstStatBlock* block,
-    NotNull<InternalErrorReporter> handle
-)
-{
-
-    LUAU_TIMETRACE_SCOPE("DataFlowGraphBuilder::build", "Typechecking");
-
-    DataFlowGraphBuilder builder;
-    builder.handle = handle;
-    DfgScope* moduleScope = builder.makeChildScope();
-    PushScope ps{builder.scopeStack, moduleScope};
-    builder.visitBlockWithoutChildScope(block);
-    builder.resolveCaptures();
-
-    if (FFlag::DebugLuauFreezeArena)
-    {
-        builder.defArena->allocator.freeze();
-        builder.keyArena->allocator.freeze();
-    }
-
-    return {std::make_shared<DataFlowGraph>(std::move(builder.graph)), std::move(builder.scopes)};
-}
-
 void DataFlowGraphBuilder::resolveCaptures()
 {
     for (const auto& [_, capture] : captures)
@@ -885,7 +878,7 @@ DataFlowResult DataFlowGraphBuilder::visitExpr(AstExprCall* c)
 {
     visitExpr(c->func);
 
-    if (FFlag::LuauTypestateBuiltins2 && shouldTypestateForFirstArgument(*c) && c->args.size > 1 && isLValue(*c->args.begin()))
+    if (shouldTypestateForFirstArgument(*c) && c->args.size > 1 && isLValue(*c->args.begin()))
     {
         AstExpr* firstArg = *c->args.begin();
 
@@ -1176,6 +1169,8 @@ void DataFlowGraphBuilder::visitType(AstType* t)
         return; // ok
     else if (auto s = t->as<AstTypeSingletonString>())
         return; // ok
+    else if (auto g = t->as<AstTypeGroup>())
+        return visitType(g->type);
     else
         handle->ice("Unknown AstType in DataFlowGraphBuilder::visitType");
 }

Analysis/src/Differ.cpp

@@ -13,7 +13,6 @@
 
 namespace Luau
 {
-
 std::string DiffPathNode::toString() const
 {
     switch (kind)
@@ -945,14 +944,12 @@ std::vector<std::pair<TypeId, TypeId>>::const_reverse_iterator DifferEnvironment
     return visitingStack.crend();
 }
 
-
 DifferResult diff(TypeId ty1, TypeId ty2)
 {
     DifferEnvironment differEnv{ty1, ty2, std::nullopt, std::nullopt};
     return diffUsingEnv(differEnv, ty1, ty2);
 }
 
-
 DifferResult diffWithSymbols(TypeId ty1, TypeId ty2, std::optional<std::string> symbol1, std::optional<std::string> symbol2)
 {
     DifferEnvironment differEnv{ty1, ty2, symbol1, symbol2};

Analysis/src/EmbeddedBuiltinDefinitions.cpp

@@ -1,15 +1,13 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #include "Luau/BuiltinDefinitions.h"
 
-LUAU_FASTFLAG(LuauMathMap)
-
-LUAU_FASTFLAGVARIABLE(LuauVectorDefinitions)
-LUAU_FASTFLAGVARIABLE(LuauVectorDefinitionsExtra)
+LUAU_FASTFLAG(LuauBufferBitMethods2)
+LUAU_FASTFLAGVARIABLE(LuauMathMapDefinition)
+LUAU_FASTFLAG(LuauVector2Constructor)
 
 namespace Luau
 {
 
-// TODO: there has to be a better way, like splitting up per library
 static const std::string kBuiltinDefinitionLuaSrcChecked_DEPRECATED = R"BUILTIN_SRC(
 
 declare bit32: {
@@ -30,227 +28,6 @@ declare bit32: {
     byteswap: @checked (n: number) -> number,
 }
 
-declare math: {
-    frexp: @checked (n: number) -> (number, number),
-    ldexp: @checked (s: number, e: number) -> number,
-    fmod: @checked (x: number, y: number) -> number,
-    modf: @checked (n: number) -> (number, number),
-    pow: @checked (x: number, y: number) -> number,
-    exp: @checked (n: number) -> number,
-
-    ceil: @checked (n: number) -> number,
-    floor: @checked (n: number) -> number,
-    abs: @checked (n: number) -> number,
-    sqrt: @checked (n: number) -> number,
-
-    log: @checked (n: number, base: number?) -> number,
-    log10: @checked (n: number) -> number,
-
-    rad: @checked (n: number) -> number,
-    deg: @checked (n: number) -> number,
-
-    sin: @checked (n: number) -> number,
-    cos: @checked (n: number) -> number,
-    tan: @checked (n: number) -> number,
-    sinh: @checked (n: number) -> number,
-    cosh: @checked (n: number) -> number,
-    tanh: @checked (n: number) -> number,
-    atan: @checked (n: number) -> number,
-    acos: @checked (n: number) -> number,
-    asin: @checked (n: number) -> number,
-    atan2: @checked (y: number, x: number) -> number,
-
-    min: @checked (number, ...number) -> number,
-    max: @checked (number, ...number) -> number,
-
-    pi: number,
-    huge: number,
-
-    randomseed: @checked (seed: number) -> (),
-    random: @checked (number?, number?) -> number,
-
-    sign: @checked (n: number) -> number,
-    clamp: @checked (n: number, min: number, max: number) -> number,
-    noise: @checked (x: number, y: number?, z: number?) -> number,
-    round: @checked (n: number) -> number,
-}
-
-type DateTypeArg = {
-    year: number,
-    month: number,
-    day: number,
-    hour: number?,
-    min: number?,
-    sec: number?,
-    isdst: boolean?,
-}
-
-type DateTypeResult = {
-    year: number,
-    month: number,
-    wday: number,
-    yday: number,
-    day: number,
-    hour: number,
-    min: number,
-    sec: number,
-    isdst: boolean,
-}
-
-declare os: {
-    time: (time: DateTypeArg?) -> number,
-    date: ((formatString: "*t" | "!*t", time: number?) -> DateTypeResult) & ((formatString: string?, time: number?) -> string),
-    difftime: (t2: DateTypeResult | number, t1: DateTypeResult | number) -> number,
-    clock: () -> number,
-}
-
-@checked declare function require(target: any): any
-
-@checked declare function getfenv(target: any): { [string]: any }
-
-declare _G: any
-declare _VERSION: string
-
-declare function gcinfo(): number
-
-declare function print<T...>(...: T...)
-
-declare function type<T>(value: T): string
-declare function typeof<T>(value: T): string
-
--- `assert` has a magic function attached that will give more detailed type information
-declare function assert<T>(value: T, errorMessage: string?): T
-declare function error<T>(message: T, level: number?): never
-
-declare function tostring<T>(value: T): string
-declare function tonumber<T>(value: T, radix: number?): number?
-
-declare function rawequal<T1, T2>(a: T1, b: T2): boolean
-declare function rawget<K, V>(tab: {[K]: V}, k: K): V
-declare function rawset<K, V>(tab: {[K]: V}, k: K, v: V): {[K]: V}
-declare function rawlen<K, V>(obj: {[K]: V} | string): number
-
-declare function setfenv<T..., R...>(target: number | (T...) -> R..., env: {[string]: any}): ((T...) -> R...)?
-
-declare function ipairs<V>(tab: {V}): (({V}, number) -> (number?, V), {V}, number)
-
-declare function pcall<A..., R...>(f: (A...) -> R..., ...: A...): (boolean, R...)
-
--- FIXME: The actual type of `xpcall` is:
--- <E, A..., R1..., R2...>(f: (A...) -> R1..., err: (E) -> R2..., A...) -> (true, R1...) | (false, R2...)
--- Since we can't represent the return value, we use (boolean, R1...).
-declare function xpcall<E, A..., R1..., R2...>(f: (A...) -> R1..., err: (E) -> R2..., ...: A...): (boolean, R1...)
-
--- `select` has a magic function attached to provide more detailed type information
-declare function select<A...>(i: string | number, ...: A...): ...any
-
--- FIXME: This type is not entirely correct - `loadstring` returns a function or
--- (nil, string).
-declare function loadstring<A...>(src: string, chunkname: string?): (((A...) -> any)?, string?)
-
-@checked declare function newproxy(mt: boolean?): any
-
-declare coroutine: {
-    create: <A..., R...>(f: (A...) -> R...) -> thread,
-    resume: <A..., R...>(co: thread, A...) -> (boolean, R...),
-    running: () -> thread,
-    status: @checked (co: thread) -> "dead" | "running" | "normal" | "suspended",
-    wrap: <A..., R...>(f: (A...) -> R...) -> ((A...) -> R...),
-    yield: <A..., R...>(A...) -> R...,
-    isyieldable: () -> boolean,
-    close: @checked (co: thread) -> (boolean, any)
-}
-
-declare table: {
-    concat: <V>(t: {V}, sep: string?, i: number?, j: number?) -> string,
-    insert: (<V>(t: {V}, value: V) -> ()) & (<V>(t: {V}, pos: number, value: V) -> ()),
-    maxn: <V>(t: {V}) -> number,
-    remove: <V>(t: {V}, number?) -> V?,
-    sort: <V>(t: {V}, comp: ((V, V) -> boolean)?) -> (),
-    create: <V>(count: number, value: V?) -> {V},
-    find: <V>(haystack: {V}, needle: V, init: number?) -> number?,
-
-    unpack: <V>(list: {V}, i: number?, j: number?) -> ...V,
-    pack: <V>(...V) -> { n: number, [number]: V },
-
-    getn: <V>(t: {V}) -> number,
-    foreach: <K, V>(t: {[K]: V}, f: (K, V) -> ()) -> (),
-    foreachi: <V>({V}, (number, V) -> ()) -> (),
-
-    move: <V>(src: {V}, a: number, b: number, t: number, dst: {V}?) -> {V},
-    clear: <K, V>(table: {[K]: V}) -> (),
-
-    isfrozen: <K, V>(t: {[K]: V}) -> boolean,
-}
-
-declare debug: {
-    info: (<R...>(thread: thread, level: number, options: string) -> R...) & (<R...>(level: number, options: string) -> R...) & (<A..., R1..., R2...>(func: (A...) -> R1..., options: string) -> R2...),
-    traceback: ((message: string?, level: number?) -> string) & ((thread: thread, message: string?, level: number?) -> string),
-}
-
-declare utf8: {
-    char: @checked (...number) -> string,
-    charpattern: string,
-    codes: @checked (str: string) -> ((string, number) -> (number, number), string, number),
-    codepoint: @checked (str: string, i: number?, j: number?) -> ...number,
-    len: @checked (s: string, i: number?, j: number?) -> (number?, number?),
-    offset: @checked (s: string, n: number?, i: number?) -> number,
-}
-
--- Cannot use `typeof` here because it will produce a polytype when we expect a monotype.
-declare function unpack<V>(tab: {V}, i: number?, j: number?): ...V
-
-
---- Buffer API
-declare buffer: {
-    create: @checked (size: number) -> buffer,
-    fromstring: @checked (str: string) -> buffer,
-    tostring: @checked (b: buffer) -> string,
-    len: @checked (b: buffer) -> number,
-    copy: @checked (target: buffer, targetOffset: number, source: buffer, sourceOffset: number?, count: number?) -> (),
-    fill: @checked (b: buffer, offset: number, value: number, count: number?) -> (),
-    readi8: @checked (b: buffer, offset: number) -> number,
-    readu8: @checked (b: buffer, offset: number) -> number,
-    readi16: @checked (b: buffer, offset: number) -> number,
-    readu16: @checked (b: buffer, offset: number) -> number,
-    readi32: @checked (b: buffer, offset: number) -> number,
-    readu32: @checked (b: buffer, offset: number) -> number,
-    readf32: @checked (b: buffer, offset: number) -> number,
-    readf64: @checked (b: buffer, offset: number) -> number,
-    writei8: @checked (b: buffer, offset: number, value: number) -> (),
-    writeu8: @checked (b: buffer, offset: number, value: number) -> (),
-    writei16: @checked (b: buffer, offset: number, value: number) -> (),
-    writeu16: @checked (b: buffer, offset: number, value: number) -> (),
-    writei32: @checked (b: buffer, offset: number, value: number) -> (),
-    writeu32: @checked (b: buffer, offset: number, value: number) -> (),
-    writef32: @checked (b: buffer, offset: number, value: number) -> (),
-    writef64: @checked (b: buffer, offset: number, value: number) -> (),
-    readstring: @checked (b: buffer, offset: number, count: number) -> string,
-    writestring: @checked (b: buffer, offset: number, value: string, count: number?) -> (),
-}
-
-)BUILTIN_SRC";
-
-static const std::string kBuiltinDefinitionLuaSrcChecked = R"BUILTIN_SRC(
-
-declare bit32: {
-    band: @checked (...number) -> number,
-    bor: @checked (...number) -> number,
-    bxor: @checked (...number) -> number,
-    btest: @checked (number, ...number) -> boolean,
-    rrotate: @checked (x: number, disp: number) -> number,
-    lrotate: @checked (x: number, disp: number) -> number,
-    lshift: @checked (x: number, disp: number) -> number,
-    arshift: @checked (x: number, disp: number) -> number,
-    rshift: @checked (x: number, disp: number) -> number,
-    bnot: @checked (x: number) -> number,
-    extract: @checked (n: number, field: number, width: number?) -> number,
-    replace: @checked (n: number, v: number, field: number, width: number?) -> number,
-    countlz: @checked (n: number) -> number,
-    countrz: @checked (n: number) -> number,
-    byteswap: @checked (n: number) -> number,
-}
-
 declare math: {
     frexp: @checked (n: number) -> (number, number),
     ldexp: @checked (s: number, e: number) -> number,
@@ -422,7 +199,231 @@ declare utf8: {
 -- Cannot use `typeof` here because it will produce a polytype when we expect a monotype.
 declare function unpack<V>(tab: {V}, i: number?, j: number?): ...V
 
+)BUILTIN_SRC";
 
+static const std::string kBuiltinDefinitionBaseSrc = R"BUILTIN_SRC(
+
+@checked declare function require(target: any): any
+
+@checked declare function getfenv(target: any): { [string]: any }
+
+declare _G: any
+declare _VERSION: string
+
+declare function gcinfo(): number
+
+declare function print<T...>(...: T...)
+
+declare function type<T>(value: T): string
+declare function typeof<T>(value: T): string
+
+-- `assert` has a magic function attached that will give more detailed type information
+declare function assert<T>(value: T, errorMessage: string?): T
+declare function error<T>(message: T, level: number?): never
+
+declare function tostring<T>(value: T): string
+declare function tonumber<T>(value: T, radix: number?): number?
+
+declare function rawequal<T1, T2>(a: T1, b: T2): boolean
+declare function rawget<K, V>(tab: {[K]: V}, k: K): V
+declare function rawset<K, V>(tab: {[K]: V}, k: K, v: V): {[K]: V}
+declare function rawlen<K, V>(obj: {[K]: V} | string): number
+
+declare function setfenv<T..., R...>(target: number | (T...) -> R..., env: {[string]: any}): ((T...) -> R...)?
+
+declare function ipairs<V>(tab: {V}): (({V}, number) -> (number?, V), {V}, number)
+
+declare function pcall<A..., R...>(f: (A...) -> R..., ...: A...): (boolean, R...)
+
+-- FIXME: The actual type of `xpcall` is:
+-- <E, A..., R1..., R2...>(f: (A...) -> R1..., err: (E) -> R2..., A...) -> (true, R1...) | (false, R2...)
+-- Since we can't represent the return value, we use (boolean, R1...).
+declare function xpcall<E, A..., R1..., R2...>(f: (A...) -> R1..., err: (E) -> R2..., ...: A...): (boolean, R1...)
+
+-- `select` has a magic function attached to provide more detailed type information
+declare function select<A...>(i: string | number, ...: A...): ...any
+
+-- FIXME: This type is not entirely correct - `loadstring` returns a function or
+-- (nil, string).
+declare function loadstring<A...>(src: string, chunkname: string?): (((A...) -> any)?, string?)
+
+@checked declare function newproxy(mt: boolean?): any
+
+-- Cannot use `typeof` here because it will produce a polytype when we expect a monotype.
+declare function unpack<V>(tab: {V}, i: number?, j: number?): ...V
+
+)BUILTIN_SRC";
+
+static const std::string kBuiltinDefinitionBit32Src = R"BUILTIN_SRC(
+
+declare bit32: {
+    band: @checked (...number) -> number,
+    bor: @checked (...number) -> number,
+    bxor: @checked (...number) -> number,
+    btest: @checked (number, ...number) -> boolean,
+    rrotate: @checked (x: number, disp: number) -> number,
+    lrotate: @checked (x: number, disp: number) -> number,
+    lshift: @checked (x: number, disp: number) -> number,
+    arshift: @checked (x: number, disp: number) -> number,
+    rshift: @checked (x: number, disp: number) -> number,
+    bnot: @checked (x: number) -> number,
+    extract: @checked (n: number, field: number, width: number?) -> number,
+    replace: @checked (n: number, v: number, field: number, width: number?) -> number,
+    countlz: @checked (n: number) -> number,
+    countrz: @checked (n: number) -> number,
+    byteswap: @checked (n: number) -> number,
+}
+
+)BUILTIN_SRC";
+
+static const std::string kBuiltinDefinitionMathSrc = R"BUILTIN_SRC(
+
+declare math: {
+    frexp: @checked (n: number) -> (number, number),
+    ldexp: @checked (s: number, e: number) -> number,
+    fmod: @checked (x: number, y: number) -> number,
+    modf: @checked (n: number) -> (number, number),
+    pow: @checked (x: number, y: number) -> number,
+    exp: @checked (n: number) -> number,
+
+    ceil: @checked (n: number) -> number,
+    floor: @checked (n: number) -> number,
+    abs: @checked (n: number) -> number,
+    sqrt: @checked (n: number) -> number,
+
+    log: @checked (n: number, base: number?) -> number,
+    log10: @checked (n: number) -> number,
+
+    rad: @checked (n: number) -> number,
+    deg: @checked (n: number) -> number,
+
+    sin: @checked (n: number) -> number,
+    cos: @checked (n: number) -> number,
+    tan: @checked (n: number) -> number,
+    sinh: @checked (n: number) -> number,
+    cosh: @checked (n: number) -> number,
+    tanh: @checked (n: number) -> number,
+    atan: @checked (n: number) -> number,
+    acos: @checked (n: number) -> number,
+    asin: @checked (n: number) -> number,
+    atan2: @checked (y: number, x: number) -> number,
+
+    min: @checked (number, ...number) -> number,
+    max: @checked (number, ...number) -> number,
+
+    pi: number,
+    huge: number,
+
+    randomseed: @checked (seed: number) -> (),
+    random: @checked (number?, number?) -> number,
+
+    sign: @checked (n: number) -> number,
+    clamp: @checked (n: number, min: number, max: number) -> number,
+    noise: @checked (x: number, y: number?, z: number?) -> number,
+    round: @checked (n: number) -> number,
+    map: @checked (x: number, inmin: number, inmax: number, outmin: number, outmax: number) -> number,
+    lerp: @checked (a: number, b: number, t: number) -> number,
+}
+
+)BUILTIN_SRC";
+
+static const std::string kBuiltinDefinitionOsSrc = R"BUILTIN_SRC(
+
+type DateTypeArg = {
+    year: number,
+    month: number,
+    day: number,
+    hour: number?,
+    min: number?,
+    sec: number?,
+    isdst: boolean?,
+}
+
+type DateTypeResult = {
+    year: number,
+    month: number,
+    wday: number,
+    yday: number,
+    day: number,
+    hour: number,
+    min: number,
+    sec: number,
+    isdst: boolean,
+}
+
+declare os: {
+    time: (time: DateTypeArg?) -> number,
+    date: ((formatString: "*t" | "!*t", time: number?) -> DateTypeResult) & ((formatString: string?, time: number?) -> string),
+    difftime: (t2: DateTypeResult | number, t1: DateTypeResult | number) -> number,
+    clock: () -> number,
+}
+
+)BUILTIN_SRC";
+
+static const std::string kBuiltinDefinitionCoroutineSrc = R"BUILTIN_SRC(
+
+declare coroutine: {
+    create: <A..., R...>(f: (A...) -> R...) -> thread,
+    resume: <A..., R...>(co: thread, A...) -> (boolean, R...),
+    running: () -> thread,
+    status: @checked (co: thread) -> "dead" | "running" | "normal" | "suspended",
+    wrap: <A..., R...>(f: (A...) -> R...) -> ((A...) -> R...),
+    yield: <A..., R...>(A...) -> R...,
+    isyieldable: () -> boolean,
+    close: @checked (co: thread) -> (boolean, any)
+}
+
+)BUILTIN_SRC";
+
+static const std::string kBuiltinDefinitionTableSrc = R"BUILTIN_SRC(
+
+declare table: {
+    concat: <V>(t: {V}, sep: string?, i: number?, j: number?) -> string,
+    insert: (<V>(t: {V}, value: V) -> ()) & (<V>(t: {V}, pos: number, value: V) -> ()),
+    maxn: <V>(t: {V}) -> number,
+    remove: <V>(t: {V}, number?) -> V?,
+    sort: <V>(t: {V}, comp: ((V, V) -> boolean)?) -> (),
+    create: <V>(count: number, value: V?) -> {V},
+    find: <V>(haystack: {V}, needle: V, init: number?) -> number?,
+
+    unpack: <V>(list: {V}, i: number?, j: number?) -> ...V,
+    pack: <V>(...V) -> { n: number, [number]: V },
+
+    getn: <V>(t: {V}) -> number,
+    foreach: <K, V>(t: {[K]: V}, f: (K, V) -> ()) -> (),
+    foreachi: <V>({V}, (number, V) -> ()) -> (),
+
+    move: <V>(src: {V}, a: number, b: number, t: number, dst: {V}?) -> {V},
+    clear: <K, V>(table: {[K]: V}) -> (),
+
+    isfrozen: <K, V>(t: {[K]: V}) -> boolean,
+}
+
+)BUILTIN_SRC";
+
+static const std::string kBuiltinDefinitionDebugSrc = R"BUILTIN_SRC(
+
+declare debug: {
+    info: (<R...>(thread: thread, level: number, options: string) -> R...) & (<R...>(level: number, options: string) -> R...) & (<A..., R1..., R2...>(func: (A...) -> R1..., options: string) -> R2...),
+    traceback: ((message: string?, level: number?) -> string) & ((thread: thread, message: string?, level: number?) -> string),
+}
+
+)BUILTIN_SRC";
+
+static const std::string kBuiltinDefinitionUtf8Src = R"BUILTIN_SRC(
+
+declare utf8: {
+    char: @checked (...number) -> string,
+    charpattern: string,
+    codes: @checked (str: string) -> ((string, number) -> (number, number), string, number),
+    codepoint: @checked (str: string, i: number?, j: number?) -> ...number,
+    len: @checked (s: string, i: number?, j: number?) -> (number?, number?),
+    offset: @checked (s: string, n: number?, i: number?) -> number,
+}
+
+)BUILTIN_SRC";
+
+static const std::string kBuiltinDefinitionBufferSrc_DEPRECATED = R"BUILTIN_SRC(
 --- Buffer API
 declare buffer: {
     create: @checked (size: number) -> buffer,
@@ -453,10 +454,47 @@ declare buffer: {
 
 )BUILTIN_SRC";
 
-static const std::string kBuiltinDefinitionVectorSrc_DEPRECATED = R"BUILTIN_SRC(
+static const std::string kBuiltinDefinitionBufferSrc = R"BUILTIN_SRC(
+--- Buffer API
+declare buffer: {
+    create: @checked (size: number) -> buffer,
+    fromstring: @checked (str: string) -> buffer,
+    tostring: @checked (b: buffer) -> string,
+    len: @checked (b: buffer) -> number,
+    copy: @checked (target: buffer, targetOffset: number, source: buffer, sourceOffset: number?, count: number?) -> (),
+    fill: @checked (b: buffer, offset: number, value: number, count: number?) -> (),
+    readi8: @checked (b: buffer, offset: number) -> number,
+    readu8: @checked (b: buffer, offset: number) -> number,
+    readi16: @checked (b: buffer, offset: number) -> number,
+    readu16: @checked (b: buffer, offset: number) -> number,
+    readi32: @checked (b: buffer, offset: number) -> number,
+    readu32: @checked (b: buffer, offset: number) -> number,
+    readf32: @checked (b: buffer, offset: number) -> number,
+    readf64: @checked (b: buffer, offset: number) -> number,
+    writei8: @checked (b: buffer, offset: number, value: number) -> (),
+    writeu8: @checked (b: buffer, offset: number, value: number) -> (),
+    writei16: @checked (b: buffer, offset: number, value: number) -> (),
+    writeu16: @checked (b: buffer, offset: number, value: number) -> (),
+    writei32: @checked (b: buffer, offset: number, value: number) -> (),
+    writeu32: @checked (b: buffer, offset: number, value: number) -> (),
+    writef32: @checked (b: buffer, offset: number, value: number) -> (),
+    writef64: @checked (b: buffer, offset: number, value: number) -> (),
+    readstring: @checked (b: buffer, offset: number, count: number) -> string,
+    writestring: @checked (b: buffer, offset: number, value: string, count: number?) -> (),
+    readbits: @checked (b: buffer, bitOffset: number, bitCount: number) -> number,
+    writebits: @checked (b: buffer, bitOffset: number, bitCount: number, value: number) -> (),
+}
 
--- TODO: this will be replaced with a built-in primitive type
-declare class vector end
+)BUILTIN_SRC";
+
+static const std::string kBuiltinDefinitionVectorSrc_NoVector2Ctor_DEPRECATED = R"BUILTIN_SRC(
+
+-- While vector would have been better represented as a built-in primitive type, type solver class handling covers most of the properties
+declare class vector
+    x: number
+    y: number
+    z: number
+end
 
 declare vector: {
     create: @checked (x: number, y: number, z: number) -> vector,
@@ -489,7 +527,7 @@ declare class vector
 end
 
 declare vector: {
-    create: @checked (x: number, y: number, z: number) -> vector,
+    create: @checked (x: number, y: number, z: number?) -> vector,
     magnitude: @checked (vec: vector) -> number,
     normalize: @checked (vec: vector) -> vector,
     cross: @checked (vec1: vector, vec2: vector) -> vector,
@@ -511,12 +549,25 @@ declare vector: {
 
 std::string getBuiltinDefinitionSource()
 {
-    std::string result = FFlag::LuauMathMap ? kBuiltinDefinitionLuaSrcChecked : kBuiltinDefinitionLuaSrcChecked_DEPRECATED;
+    std::string result = FFlag::LuauMathMapDefinition ? kBuiltinDefinitionBaseSrc : kBuiltinDefinitionLuaSrcChecked_DEPRECATED;
 
-    if (FFlag::LuauVectorDefinitionsExtra)
+    if (FFlag::LuauMathMapDefinition)
+    {
+        result += kBuiltinDefinitionBit32Src;
+        result += kBuiltinDefinitionMathSrc;
+        result += kBuiltinDefinitionOsSrc;
+        result += kBuiltinDefinitionCoroutineSrc;
+        result += kBuiltinDefinitionTableSrc;
+        result += kBuiltinDefinitionDebugSrc;
+        result += kBuiltinDefinitionUtf8Src;
+    }
+
+    result += FFlag::LuauBufferBitMethods2 ? kBuiltinDefinitionBufferSrc : kBuiltinDefinitionBufferSrc_DEPRECATED;
+
+    if (FFlag::LuauVector2Constructor)
         result += kBuiltinDefinitionVectorSrc;
-    else if (FFlag::LuauVectorDefinitions)
-        result += kBuiltinDefinitionVectorSrc_DEPRECATED;
+    else
+        result += kBuiltinDefinitionVectorSrc_NoVector2Ctor_DEPRECATED;
 
     return result;
 }

Analysis/src/EqSatSimplification.cpp

@@ -92,18 +92,24 @@ size_t TTable::Hash::operator()(const TTable& value) const
     return hash;
 }
 
-uint32_t StringCache::add(std::string_view s)
+StringId StringCache::add(std::string_view s)
 {
-    size_t hash = std::hash<std::string_view>()(s);
-    if (uint32_t* it = strings.find(hash))
+    /* Important subtlety: This use of DenseHashMap<std::string_view, StringId>
+     * is okay because std::hash<std::string_view> works solely on the bytes
+     * referred by the string_view.
+     *
+     * In other words, two string views which contain the same bytes will have
+     * the same hash whether or not their addresses are the same.
+     */
+    if (StringId* it = strings.find(s))
         return *it;
 
     char* storage = static_cast<char*>(allocator.allocate(s.size()));
     memcpy(storage, s.data(), s.size());
 
-    uint32_t result = uint32_t(views.size());
+    StringId result = StringId(views.size());
     views.emplace_back(storage, s.size());
-    strings[hash] = result;
+    strings[s] = result;
     return result;
 }
 
@@ -143,6 +149,61 @@ static bool isTerminal(const EType& node)
            node.get<TNever>() || node.get<TNoRefine>();
 }
 
+static bool areTerminalAndDefinitelyDisjoint(const EType& lhs, const EType& rhs)
+{
+    // If either node is non-terminal, then we early exit: we're not going to
+    // do a state space search for whether something like:
+    //  (A | B | C | D) & (E | F | G | H)
+    // ... is a disjoint intersection.
+    if (!isTerminal(lhs) || !isTerminal(rhs))
+        return false;
+
+    // Special case some types that aren't strict, disjoint subsets.
+    if (lhs.get<TTopClass>() || lhs.get<TClass>())
+        return !(rhs.get<TTopClass>() || rhs.get<TClass>());
+
+    // Handling strings / booleans: these are the types for which we
+    // expect something like:
+    //
+    //  "foo" & ~"bar"
+    //
+    // ... to simplify to "foo".
+    if (lhs.get<TString>())
+        return !(rhs.get<TString>() || rhs.get<SString>());
+
+    if (lhs.get<TBoolean>())
+        return !(rhs.get<TBoolean>() || rhs.get<SBoolean>());
+
+    if (auto lhsSString = lhs.get<SString>())
+    {
+        auto rhsSString = rhs.get<SString>();
+        if (!rhsSString)
+            return !rhs.get<TString>();
+        return lhsSString->value() != rhsSString->value();
+    }
+
+    if (auto lhsSBoolean = lhs.get<SBoolean>())
+    {
+        auto rhsSBoolean = rhs.get<SBoolean>();
+        if (!rhsSBoolean)
+            return !rhs.get<TBoolean>();
+        return lhsSBoolean->value() != rhsSBoolean->value();
+    }
+
+    // At this point:
+    // - We know both nodes are terminal
+    // - We know that the LHS is not any boolean, string, or class
+    // At this point, we have two classes of checks left:
+    // - Whether the two enodes are exactly the same set (now that the static
+    //   sets have been covered).
+    // - Whether one of the enodes is a large semantic set such as TAny,
+    //   TUnknown, or TError.
+    return !(
+        lhs.index() == rhs.index() || lhs.get<TUnknown>() || rhs.get<TUnknown>() || lhs.get<TAny>() || rhs.get<TAny>() || lhs.get<TNoRefine>() ||
+        rhs.get<TNoRefine>() || lhs.get<TError>() || rhs.get<TError>() || lhs.get<TOpaque>() || rhs.get<TOpaque>()
+    );
+}
+
 static bool isTerminal(const EGraph& egraph, Id eclass)
 {
     const auto& nodes = egraph[eclass].nodes;
@@ -151,7 +212,7 @@ static bool isTerminal(const EGraph& egraph, Id eclass)
         nodes.end(),
         [](auto& a)
         {
-            return isTerminal(a);
+            return isTerminal(a.node);
         }
     );
 }
@@ -335,11 +396,31 @@ Id toId(
     {
         LUAU_ASSERT(tfun->packArguments.empty());
 
+        if (tfun->userFuncName) {
+            // TODO: User defined type functions are pseudo-effectful: error
+            // reporting is done via the `print` statement, so running a
+            // UDTF multiple times may end up double erroring. egraphs
+            // currently may induce type functions to be reduced multiple
+            // times. We should probably opt _not_ to process user defined
+            // type functions at all.
+            return egraph.add(TOpaque{ty});
+        }
+
         std::vector<Id> parts;
+        parts.reserve(tfun->typeArguments.size());
         for (TypeId part : tfun->typeArguments)
             parts.push_back(toId(egraph, builtinTypes, mappingIdToClass, typeToMappingId, boundNodes, strings, part));
 
-        return cache(egraph.add(TTypeFun{tfun->function.get(), std::move(parts)}));
+        // This looks sily, but we're making a copy of the specific
+        // `TypeFunctionInstanceType` outside of the provided arena so that
+        // we can access the members without fear of the specific TFIT being
+        // overwritten with a bound type.
+        return cache(egraph.add(TTypeFun{
+            std::make_shared<const TypeFunctionInstanceType>(
+                tfun->function, tfun->typeArguments, tfun->packArguments, tfun->userFuncName, tfun->userFuncData
+            ),
+            std::move(parts)
+        }));
     }
     else if (get<NoRefineType>(ty))
         return egraph.add(TNoRefine{});
@@ -399,7 +480,7 @@ static size_t computeCost(std::unordered_map<Id, size_t>& bestNodes, const EGrap
     if (auto it = costs.find(id); it != costs.end())
         return it->second;
 
-    const std::vector<EType>& nodes = egraph[id].nodes;
+    const std::vector<Node<EType>>& nodes = egraph[id].nodes;
 
     size_t minCost = std::numeric_limits<size_t>::max();
     size_t bestNode = std::numeric_limits<size_t>::max();
@@ -416,7 +497,7 @@ static size_t computeCost(std::unordered_map<Id, size_t>& bestNodes, const EGrap
     // First, quickly scan for a terminal type.  If we can find one, it is obviously the best.
     for (size_t index = 0; index < nodes.size(); ++index)
     {
-        if (isTerminal(nodes[index]))
+        if (isTerminal(nodes[index].node))
         {
             minCost = 1;
             bestNode = index;
@@ -468,44 +549,44 @@ static size_t computeCost(std::unordered_map<Id, size_t>& bestNodes, const EGrap
     {
         const auto& node = nodes[index];
 
-        if (node.get<TBound>())
+        if (node.node.get<TBound>())
             updateCost(BOUND_PENALTY, index); // TODO: This could probably be an assert now that we don't need rewrite rules to handle TBound.
-        else if (node.get<TFunction>())
+        else if (node.node.get<TFunction>())
         {
             minCost = 1;
             bestNode = index;
         }
-        else if (auto tbl = node.get<TTable>())
+        else if (auto tbl = node.node.get<TTable>())
         {
             // TODO: We could make the penalty a parameter to computeChildren.
             std::optional<size_t> maybeCost = computeChildren(tbl->operands(), minCost);
             if (maybeCost)
                 updateCost(TABLE_TYPE_PENALTY + *maybeCost, index);
         }
-        else if (node.get<TImportedTable>())
+        else if (node.node.get<TImportedTable>())
         {
             minCost = IMPORTED_TABLE_PENALTY;
             bestNode = index;
         }
-        else if (auto u = node.get<Union>())
+        else if (auto u = node.node.get<Union>())
         {
             std::optional<size_t> maybeCost = computeChildren(u->operands(), minCost);
             if (maybeCost)
                 updateCost(SET_TYPE_PENALTY + *maybeCost, index);
         }
-        else if (auto i = node.get<Intersection>())
+        else if (auto i = node.node.get<Intersection>())
         {
             std::optional<size_t> maybeCost = computeChildren(i->operands(), minCost);
             if (maybeCost)
                 updateCost(SET_TYPE_PENALTY + *maybeCost, index);
         }
-        else if (auto negation = node.get<Negation>())
+        else if (auto negation = node.node.get<Negation>())
         {
             std::optional<size_t> maybeCost = computeChildren(negation->operands(), minCost);
             if (maybeCost)
                 updateCost(NEGATION_PENALTY + *maybeCost, index);
         }
-        else if (auto tfun = node.get<TTypeFun>())
+        else if (auto tfun = node.node.get<TTypeFun>())
         {
             std::optional<size_t> maybeCost = computeChildren(tfun->operands(), minCost);
             if (maybeCost)
@@ -574,28 +655,34 @@ TypeId flattenTableNode(
             // If a TTable is its own basis, it must be the case that some other
             // node on this eclass is a TImportedTable.  Let's use that.
 
+            bool found = false;
+
             for (size_t i = 0; i < eclass.nodes.size(); ++i)
             {
-                if (eclass.nodes[i].get<TImportedTable>())
+                if (eclass.nodes[i].node.get<TImportedTable>())
                 {
+                    found = true;
                     index = i;
                     break;
                 }
             }
 
-            // If we couldn't find one, we don't know what to do.  Use ErrorType.
-            LUAU_ASSERT(0);
-            return builtinTypes->errorType;
+            if (!found)
+            {
+                // If we couldn't find one, we don't know what to do.  Use ErrorType.
+                LUAU_ASSERT(0);
+                return builtinTypes->errorType;
+            }
         }
 
         const auto& node = eclass.nodes[index];
-        if (const TTable* ttable = node.get<TTable>())
+        if (const TTable* ttable = node.node.get<TTable>())
         {
             stack.push_back(ttable);
             id = ttable->getBasis();
             continue;
         }
-        else if (const TImportedTable* ti = node.get<TImportedTable>())
+        else if (const TImportedTable* ti = node.node.get<TImportedTable>())
         {
             importedTable = ti;
             break;
@@ -622,7 +709,8 @@ TypeId flattenTableNode(
             StringId propName = t->propNames[i];
             const Id propType = t->propTypes()[i];
 
-            resultTable.props[strings.asString(propName)] = Property{fromId(egraph, strings, builtinTypes, arena, bestNodes, seen, newTypeFunctions, propType)};
+            resultTable.props[strings.asString(propName)] =
+                Property{fromId(egraph, strings, builtinTypes, arena, bestNodes, seen, newTypeFunctions, propType)};
         }
     }
 
@@ -646,7 +734,7 @@ TypeId fromId(
     size_t index = bestNodes.at(rootId);
     LUAU_ASSERT(index <= egraph[rootId].nodes.size());
 
-    const EType& node = egraph[rootId].nodes[index];
+    const EType& node = egraph[rootId].nodes[index].node;
 
     if (node.get<TNil>())
         return builtinTypes->nilType;
@@ -703,7 +791,20 @@ TypeId fromId(
         if (parts.empty())
             return builtinTypes->neverType;
         else if (parts.size() == 1)
-            return fromId(egraph, strings, builtinTypes, arena, bestNodes, seen, newTypeFunctions, parts[0]);
+        {
+            TypeId placeholder = arena->addType(BlockedType{});
+            seen[rootId] = placeholder;
+            auto result = fromId(egraph, strings, builtinTypes, arena, bestNodes, seen, newTypeFunctions, parts[0]);
+            if (follow(result) == placeholder)
+            {
+                emplaceType<GenericType>(asMutable(placeholder), "EGRAPH-SINGLETON-CYCLE");
+            }
+            else
+            {
+                emplaceType<BoundType>(asMutable(placeholder), result);
+            }
+            return result;
+        }
         else
         {
             TypeId res = arena->addType(BlockedType{});
@@ -768,7 +869,11 @@ TypeId fromId(
         for (Id part : tfun->operands())
             args.push_back(fromId(egraph, strings, builtinTypes, arena, bestNodes, seen, newTypeFunctions, part));
 
-        asMutable(res)->ty.emplace<TypeFunctionInstanceType>(*tfun->value(), std::move(args));
+        auto oldInstance = tfun->value();
+
+        asMutable(res)->ty.emplace<TypeFunctionInstanceType>(
+            oldInstance->function, std::move(args), std::vector<TypePackId>(), oldInstance->userFuncName, oldInstance->userFuncData
+        );
 
         newTypeFunctions.push_back(res);
 
@@ -848,12 +953,20 @@ std::string mkDesc(
     const int RULE_PADDING = 35;
     const std::string rulePadding(std::max<size_t>(0, RULE_PADDING - rule.size()), ' ');
     const std::string fromIdStr = ""; // "(" + std::to_string(uint32_t(from)) + ") ";
-    const std::string toIdStr = ""; // "(" + std::to_string(uint32_t(to)) + ") ";
+    const std::string toIdStr = "";   // "(" + std::to_string(uint32_t(to)) + ") ";
 
     return rule + ":" + rulePadding + fromIdStr + toString(fromTy, opts) + " <=> " + toIdStr + toString(toTy, opts);
 }
 
-std::string mkDesc(EGraph& egraph, const StringCache& strings, NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtinTypes, Id from, Id to, const std::string& rule)
+std::string mkDesc(
+    EGraph& egraph,
+    const StringCache& strings,
+    NotNull<TypeArena> arena,
+    NotNull<BuiltinTypes> builtinTypes,
+    Id from,
+    Id to,
+    const std::string& rule
+)
 {
     if (!FFlag::DebugLuauLogSimplification)
         return "";
@@ -906,7 +1019,7 @@ static std::string getNodeName(const StringCache& strings, const EType& node)
     else if (node.get<TNever>())
         return "never";
     else if (auto tfun = node.get<TTypeFun>())
-        return "tfun " + tfun->value()->name;
+        return "tfun " + tfun->value()->function->name;
     else if (node.get<Negation>())
         return "~";
     else if (node.get<Invalid>())
@@ -928,8 +1041,9 @@ std::string toDot(const StringCache& strings, const EGraph& egraph)
 
     for (const auto& [id, eclass] : egraph.getAllClasses())
     {
-        for (const auto& node : eclass.nodes)
+        for (const auto& n : eclass.nodes)
         {
+            const EType& node = n.node;
             if (!node.operands().empty())
                 populated.insert(id);
             for (Id op : node.operands())
@@ -950,7 +1064,7 @@ std::string toDot(const StringCache& strings, const EGraph& egraph)
 
         for (size_t index = 0; index < eclass.nodes.size(); ++index)
         {
-            const auto& node = eclass.nodes[index];
+            const auto& node = eclass.nodes[index].node;
 
             const std::string label = getNodeName(strings, node);
             const std::string nodeName = "n" + std::to_string(uint32_t(id)) + "_" + std::to_string(index);
@@ -965,7 +1079,7 @@ std::string toDot(const StringCache& strings, const EGraph& egraph)
     {
         for (size_t index = 0; index < eclass.nodes.size(); ++index)
         {
-            const auto& node = eclass.nodes[index];
+            const auto& node = eclass.nodes[index].node;
 
             const std::string label = getNodeName(strings, node);
             const std::string nodeName = "n" + std::to_string(uint32_t(egraph.find(id))) + "_" + std::to_string(index);
@@ -1001,7 +1115,7 @@ static Tag const* isTag(const EGraph& egraph, Id id)
 {
     for (const auto& node : egraph[id].nodes)
     {
-        if (auto n = isTag<Tag>(node))
+        if (auto n = isTag<Tag>(node.node))
             return n;
     }
     return nullptr;
@@ -1037,7 +1151,7 @@ protected:
     {
         for (const auto& node : (*egraph)[id].nodes)
         {
-            if (auto n = node.get<Tag>())
+            if (auto n = node.node.get<Tag>())
                 return n;
         }
         return nullptr;
@@ -1225,8 +1339,10 @@ const EType* findSubtractableClass(const EGraph& egraph, std::unordered_set<Id>&
     const EType* bestUnion = nullptr;
     std::optional<size_t> unionSize;
 
-    for (const auto& node : egraph[id].nodes)
+    for (const auto& n : egraph[id].nodes)
     {
+        const EType& node = n.node;
+
         if (isTerminal(node))
             return &node;
 
@@ -1342,14 +1458,14 @@ bool subtract(EGraph& egraph, CanonicalizedType& ct, Id part)
     return true;
 }
 
-Id fromCanonicalized(EGraph& egraph, CanonicalizedType& ct)
+static std::pair<Id, size_t> fromCanonicalized(EGraph& egraph, CanonicalizedType& ct)
 {
     if (ct.isUnknown())
     {
         if (ct.errorPart)
-            return egraph.add(TAny{});
+            return {egraph.add(TAny{}), 1};
         else
-            return egraph.add(TUnknown{});
+            return {egraph.add(TUnknown{}), 1};
     }
 
     std::vector<Id> parts;
@@ -1387,7 +1503,12 @@ Id fromCanonicalized(EGraph& egraph, CanonicalizedType& ct)
     parts.insert(parts.end(), ct.functionParts.begin(), ct.functionParts.end());
     parts.insert(parts.end(), ct.otherParts.begin(), ct.otherParts.end());
 
-    return mkUnion(egraph, std::move(parts));
+    std::sort(parts.begin(), parts.end());
+    auto it = std::unique(parts.begin(), parts.end());
+    parts.erase(it, parts.end());
+
+    const size_t size = parts.size();
+    return {mkUnion(egraph, std::move(parts)), size};
 }
 
 void addChildren(const EGraph& egraph, const EType* enode, VecDeque<Id>& worklist)
@@ -1433,7 +1554,7 @@ const Tag* Simplifier::isTag(Id id) const
 {
     for (const auto& node : get(id).nodes)
     {
-        if (const Tag* ty = node.get<Tag>())
+        if (const Tag* ty = node.node.get<Tag>())
             return ty;
     }
 
@@ -1467,6 +1588,16 @@ void Simplifier::subst(Id from, Id to, const std::string& ruleName, const std::u
     substs.emplace_back(from, to, desc);
 }
 
+void Simplifier::subst(Id from, size_t boringIndex, Id to, const std::string& ruleName, const std::unordered_map<Id, size_t>& forceNodes)
+{
+    std::string desc;
+    if (FFlag::DebugLuauLogSimplification)
+        desc = mkDesc(egraph, stringCache, arena, builtinTypes, from, to, forceNodes, ruleName);
+
+    egraph.markBoring(from, boringIndex);
+    substs.emplace_back(from, to, desc);
+}
+
 void Simplifier::unionClasses(std::vector<Id>& hereParts, Id there)
 {
     if (1 == hereParts.size() && isTag<TTopClass>(hereParts[0]))
@@ -1517,9 +1648,12 @@ void Simplifier::simplifyUnion(Id id)
         for (Id part : u->operands())
             unionWithType(egraph, canonicalized, find(part));
 
-        Id resultId = fromCanonicalized(egraph, canonicalized);
+        const auto [resultId, newSize] = fromCanonicalized(egraph, canonicalized);
 
-        subst(id, resultId, "simplifyUnion", {{id, unionIndex}});
+        if (newSize < u->operands().size())
+            subst(id, unionIndex, resultId, "simplifyUnion", {{id, unionIndex}});
+        else
+            subst(id, resultId, "simplifyUnion", {{id, unionIndex}});
     }
 }
 
@@ -1552,11 +1686,6 @@ std::optional<EType> intersectOne(EGraph& egraph, Id hereId, const EType* hereNo
         thereNode->get<Intersection>() || thereNode->get<Negation>() || hereNode->get<TOpaque>() || thereNode->get<TOpaque>())
         return std::nullopt;
 
-    if (hereNode->get<TAny>())
-        return *thereNode;
-    if (thereNode->get<TAny>())
-        return *hereNode;
-
     if (hereNode->get<TUnknown>())
         return *thereNode;
     if (thereNode->get<TUnknown>())
@@ -1732,7 +1861,7 @@ void Simplifier::uninhabitedIntersection(Id id)
             const auto& partNodes = egraph[partId].nodes;
             for (size_t partIndex = 0; partIndex < partNodes.size(); ++partIndex)
             {
-                const EType& N = partNodes[partIndex];
+                const EType& N = partNodes[partIndex].node;
                 if (std::optional<EType> intersection = intersectOne(egraph, accumulator, &accumulatorNode, partId, &N))
                 {
                     if (isTag<TNever>(*intersection))
@@ -1755,9 +1884,14 @@ void Simplifier::uninhabitedIntersection(Id id)
         if ((unsimplified.empty() || !isTag<TUnknown>(accumulator)) && find(accumulator) != id)
             unsimplified.push_back(accumulator);
 
+        const bool isSmaller = unsimplified.size() < parts.size();
+
         const Id result = mkIntersection(egraph, std::move(unsimplified));
 
-        subst(id, result, "uninhabitedIntersection", {{id, index}});
+        if (isSmaller)
+            subst(id, index, result, "uninhabitedIntersection", {{id, index}});
+        else
+            subst(id, result, "uninhabitedIntersection", {{id, index}});
     }
 }
 
@@ -1788,14 +1922,19 @@ void Simplifier::intersectWithNegatedClass(Id id)
                     const auto& iNodes = egraph[iId].nodes;
                     for (size_t iIndex = 0; iIndex < iNodes.size(); ++iIndex)
                     {
-                        const EType& iNode = iNodes[iIndex];
+                        const EType& iNode = iNodes[iIndex].node;
                         if (isTag<TNil>(iNode) || isTag<TBoolean>(iNode) || isTag<TNumber>(iNode) || isTag<TString>(iNode) || isTag<TThread>(iNode) ||
                             isTag<TTopFunction>(iNode) ||
                             // isTag<TTopTable>(iNode) || // I'm not sure about this one.
                             isTag<SBoolean>(iNode) || isTag<SString>(iNode) || isTag<TFunction>(iNode) || isTag<TNever>(iNode))
                         {
                             // eg string & ~SomeClass
-                            subst(id, iId, "intersectClassWithNegatedClass", {{id, intersectionIndex}, {iId, iIndex}, {jId, negationIndex}, {negated, negatedClassIndex}});
+                            subst(
+                                id,
+                                iId,
+                                "intersectClassWithNegatedClass",
+                                {{id, intersectionIndex}, {iId, iIndex}, {jId, negationIndex}, {negated, negatedClassIndex}}
+                            );
                             return;
                         }
 
@@ -1803,27 +1942,37 @@ void Simplifier::intersectWithNegatedClass(Id id)
                         {
                             switch (relateClasses(class_, negatedClass))
                             {
-                                case LeftSuper:
-                                    // eg Instance & ~Part
-                                    // This cannot be meaningfully reduced.
-                                    continue;
-                                case RightSuper:
-                                    subst(id, egraph.add(TNever{}), "intersectClassWithNegatedClass", {{id, intersectionIndex}, {iId, iIndex}, {jId, negationIndex}, {negated, negatedClassIndex}});
-                                    return;
-                                case Unrelated:
-                                    // Part & ~Folder == Part
+                            case LeftSuper:
+                                // eg Instance & ~Part
+                                // This cannot be meaningfully reduced.
+                                continue;
+                            case RightSuper:
+                                subst(
+                                    id,
+                                    egraph.add(TNever{}),
+                                    "intersectClassWithNegatedClass",
+                                    {{id, intersectionIndex}, {iId, iIndex}, {jId, negationIndex}, {negated, negatedClassIndex}}
+                                );
+                                return;
+                            case Unrelated:
+                                // Part & ~Folder == Part
+                                {
+                                    std::vector<Id> newParts;
+                                    newParts.reserve(intersection->operands().size() - 1);
+                                    for (Id part : intersection->operands())
                                     {
-                                        std::vector<Id> newParts;
-                                        newParts.reserve(intersection->operands().size() - 1);
-                                        for (Id part : intersection->operands())
-                                        {
-                                            if (part != jId)
-                                                newParts.push_back(part);
-                                        }
-
-                                        Id substId = egraph.add(Intersection{newParts.begin(), newParts.end()});
-                                        subst(id, substId, "intersectClassWithNegatedClass", {{id, intersectionIndex}, {iId, iIndex}, {jId, negationIndex}, {negated, negatedClassIndex}});
+                                        if (part != jId)
+                                            newParts.push_back(part);
                                     }
+
+                                    Id substId = mkIntersection(egraph, newParts);
+                                    subst(
+                                        id,
+                                        substId,
+                                        "intersectClassWithNegatedClass",
+                                        {{id, intersectionIndex}, {iId, iIndex}, {jId, negationIndex}, {negated, negatedClassIndex}}
+                                    );
+                                }
                             }
                         }
                     }
@@ -1839,6 +1988,74 @@ void Simplifier::intersectWithNegatedClass(Id id)
     }
 }
 
+void Simplifier::intersectWithNegatedAtom(Id id)
+{
+    // Let I and ~J be two arbitrary distinct operands of an intersection where
+    // I and J are terminal but are not type variables. (free, generic, or
+    // otherwise opaque)
+    //
+    // If I and J are equal, then the whole intersection is equivalent to never.
+    //
+    // If I and J are inequal, then J & ~I == J
+
+    for (const auto [intersection, intersectionIndex] : Query<Intersection>(&egraph, id))
+    {
+        const Slice<const Id>& intersectionOperands = intersection->operands();
+        for (size_t i = 0; i < intersectionOperands.size(); ++i)
+        {
+            for (const auto [negation, negationIndex] : Query<Negation>(&egraph, intersectionOperands[i]))
+            {
+                for (size_t negationOperandIndex = 0; negationOperandIndex < egraph[negation->operands()[0]].nodes.size(); ++negationOperandIndex)
+                {
+                    const EType* negationOperand = &egraph[negation->operands()[0]].nodes[negationOperandIndex].node;
+                    if (!isTerminal(*negationOperand) || negationOperand->get<TOpaque>())
+                        continue;
+
+                    for (size_t j = 0; j < intersectionOperands.size(); ++j)
+                    {
+                        if (j == i)
+                            continue;
+
+                        for (size_t jNodeIndex = 0; jNodeIndex < egraph[intersectionOperands[j]].nodes.size(); ++jNodeIndex)
+                        {
+                            const EType* jNode = &egraph[intersectionOperands[j]].nodes[jNodeIndex].node;
+                            if (!isTerminal(*jNode) || jNode->get<TOpaque>())
+                                continue;
+
+                            if (*negationOperand == *jNode)
+                            {
+                                // eg "Hello" & ~"Hello"
+                                // or boolean & ~boolean
+                                subst(
+                                    id,
+                                    egraph.add(TNever{}),
+                                    "intersectWithNegatedAtom",
+                                    {{id, intersectionIndex}, {intersectionOperands[i], negationIndex}, {intersectionOperands[j], jNodeIndex}}
+                                );
+                                return;
+                            }
+                            else if (areTerminalAndDefinitelyDisjoint(*jNode, *negationOperand))
+                            {
+                                // eg "Hello" & ~"World"
+                                // or boolean & ~string
+                                std::vector<Id> newOperands(intersectionOperands.begin(), intersectionOperands.end());
+                                newOperands.erase(newOperands.begin() + std::vector<Id>::difference_type(i));
+
+                                subst(
+                                    id,
+                                    mkIntersection(egraph, std::move(newOperands)),
+                                    "intersectWithNegatedAtom",
+                                    {{id, intersectionIndex}, {intersectionOperands[i], negationIndex}, {intersectionOperands[j], jNodeIndex}}
+                                );
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
 void Simplifier::intersectWithNoRefine(Id id)
 {
     for (const auto pair : Query<Intersection>(&egraph, id))
@@ -2003,7 +2220,7 @@ void Simplifier::expandNegation(Id id)
         if (!ok)
             continue;
 
-        subst(id, fromCanonicalized(egraph, canonicalized), "expandNegation", {{id, index}});
+        subst(id, fromCanonicalized(egraph, canonicalized).first, "expandNegation", {{id, index}});
     }
 }
 
@@ -2160,7 +2377,7 @@ void Simplifier::intersectTableProperty(Id id)
 
                             subst(
                                 id,
-                                egraph.add(Intersection{std::move(newIntersectionParts)}),
+                                mkIntersection(egraph, std::move(newIntersectionParts)),
                                 "intersectTableProperty",
                                 {{id, intersectionIndex}, {iId, table1Index}, {jId, table2Index}}
                             );
@@ -2250,7 +2467,7 @@ void Simplifier::builtinTypeFunctions(Id id)
         if (args.size() != 2)
             continue;
 
-        const std::string& name = tfun->value()->name;
+        const std::string& name = tfun->value()->function->name;
         if (name == "add" || name == "sub" || name == "mul" || name == "div" || name == "idiv" || name == "pow" || name == "mod")
         {
             if (isTag<TNumber>(args[0]) && isTag<TNumber>(args[1]))
@@ -2272,15 +2489,43 @@ void Simplifier::iffyTypeFunctions(Id id)
     {
         const Slice<const Id>& args = tfun->operands();
 
-        const std::string& name = tfun->value()->name;
+        const std::string& name = tfun->value()->function->name;
 
         if (name == "union")
             subst(id, add(Union{std::vector(args.begin(), args.end())}), "iffyTypeFunctions", {{id, index}});
-        else if (name == "intersect" || name == "refine")
+        else if (name == "intersect")
             subst(id, add(Intersection{std::vector(args.begin(), args.end())}), "iffyTypeFunctions", {{id, index}});
     }
 }
 
+// Replace instances of `lt<X, Y>` and `le<X, Y>` when either X or Y is `number`
+// or `string` with `boolean`. Lua semantics are that if we see the expression:
+//
+//   x < y
+//
+// ... we error if `x` and `y` don't have the same type. We know that for
+// `string` and `number`, comparisons will always return a boolean. So if either
+// of the arguments to `lt<>` are equivalent to `number` or `string`, then the
+// type is effectively `boolean`: either the other type is equivalent, in which
+// case we eval to `boolean`, or we diverge (raise an error).
+void Simplifier::strictMetamethods(Id id)
+{
+    for (const auto [tfun, index] : Query<TTypeFun>(&egraph, id))
+    {
+        const Slice<const Id>& args = tfun->operands();
+
+        const std::string& name = tfun->value()->function->name;
+
+        if (!(name == "lt" || name == "le") || args.size() != 2)
+            continue;
+
+        if (isTag<TNumber>(args[0]) || isTag<TString>(args[0]) || isTag<TNumber>(args[1]) || isTag<TString>(args[1]))
+        {
+            subst(id, add(TBoolean{}), __FUNCTION__, {{id, index}});
+        }
+    }
+}
+
 static void deleteSimplifier(Simplifier* s)
 {
     delete s;
@@ -2308,6 +2553,7 @@ std::optional<EqSatSimplificationResult> eqSatSimplify(NotNull<Simplifier> simpl
         &Simplifier::simplifyUnion,
         &Simplifier::uninhabitedIntersection,
         &Simplifier::intersectWithNegatedClass,
+        &Simplifier::intersectWithNegatedAtom,
         &Simplifier::intersectWithNoRefine,
         &Simplifier::cyclicIntersectionOfUnion,
         &Simplifier::cyclicUnionOfIntersection,
@@ -2318,6 +2564,7 @@ std::optional<EqSatSimplificationResult> eqSatSimplify(NotNull<Simplifier> simpl
         &Simplifier::unneededTableModification,
         &Simplifier::builtinTypeFunctions,
         &Simplifier::iffyTypeFunctions,
+        &Simplifier::strictMetamethods,
     };
 
     std::unordered_set<Id> seen;
@@ -2371,9 +2618,9 @@ std::optional<EqSatSimplificationResult> eqSatSimplify(NotNull<Simplifier> simpl
             // try to run any rules on it.
             bool shouldAbort = false;
 
-            for (const EType& enode : egraph[id].nodes)
+            for (const auto& enode : egraph[id].nodes)
             {
-                if (isTerminal(enode))
+                if (isTerminal(enode.node))
                 {
                     shouldAbort = true;
                     break;
@@ -2383,8 +2630,8 @@ std::optional<EqSatSimplificationResult> eqSatSimplify(NotNull<Simplifier> simpl
             if (shouldAbort)
                 continue;
 
-            for (const EType& enode : egraph[id].nodes)
-                addChildren(egraph, &enode, worklist);
+            for (const auto& enode : egraph[id].nodes)
+                addChildren(egraph, &enode.node, worklist);
 
             for (Simplifier::RewriteRuleFn rule : rules)
                 (simplifier.get()->*rule)(id);

Analysis/src/FragmentAutocomplete.cpp

@@ -6,6 +6,7 @@
 #include "Luau/Autocomplete.h"
 #include "Luau/Common.h"
 #include "Luau/EqSatSimplification.h"
+#include "Luau/ModuleResolver.h"
 #include "Luau/Parser.h"
 #include "Luau/ParseOptions.h"
 #include "Luau/Module.h"
@@ -19,16 +20,21 @@
 #include "Luau/Parser.h"
 #include "Luau/ParseOptions.h"
 #include "Luau/Module.h"
-
+#include "Luau/Clone.h"
 #include "AutocompleteCore.h"
 
-
 LUAU_FASTINT(LuauTypeInferRecursionLimit);
 LUAU_FASTINT(LuauTypeInferIterationLimit);
 LUAU_FASTINT(LuauTarjanChildLimit)
 LUAU_FASTFLAG(LuauAllowFragmentParsing);
 LUAU_FASTFLAG(LuauAutocompleteRefactorsForIncrementalAutocomplete)
 
+LUAU_FASTFLAGVARIABLE(LuauIncrementalAutocompleteBugfixes)
+LUAU_FASTFLAG(LuauReferenceAllocatorInNewSolver)
+LUAU_FASTFLAGVARIABLE(LuauMixedModeDefFinderTraversesTypeOf)
+LUAU_FASTFLAG(LuauBetterReverseDependencyTracking)
+LUAU_FASTFLAGVARIABLE(LuauCloneIncrementalModule)
+
 namespace
 {
 template<typename T>
@@ -49,6 +55,96 @@ void copyModuleMap(Luau::DenseHashMap<K, V>& result, const Luau::DenseHashMap<K,
 namespace Luau
 {
 
+template<typename K, typename V>
+void cloneModuleMap(TypeArena& destArena, CloneState& cloneState, const Luau::DenseHashMap<K, V>& source, Luau::DenseHashMap<K, V>& dest)
+{
+    for (auto [k, v] : source)
+    {
+        dest[k] = Luau::clone(v, destArena, cloneState);
+    }
+}
+
+struct MixedModeIncrementalTCDefFinder : public AstVisitor
+{
+    bool visit(AstExprLocal* local) override
+    {
+        referencedLocalDefs.emplace_back(local->local, local);
+        return true;
+    }
+
+    bool visit(AstTypeTypeof* node) override
+    {
+        // We need to traverse typeof expressions because they may refer to locals that we need
+        // to populate the local environment for fragment typechecking. For example, `typeof(m)`
+        // requires that we find the local/global `m` and place it in the environment.
+        // The default behaviour here is to return false, and have individual visitors override
+        // the specific behaviour they need.
+        return FFlag::LuauMixedModeDefFinderTraversesTypeOf;
+    }
+
+    // ast defs is just a mapping from expr -> def in general
+    // will get built up by the dfg builder
+
+    // localDefs, we need to copy over
+    std::vector<std::pair<AstLocal*, AstExpr*>> referencedLocalDefs;
+};
+
+void cloneAndSquashScopes(
+    CloneState& cloneState,
+    const Scope* staleScope,
+    const ModulePtr& staleModule,
+    NotNull<TypeArena> destArena,
+    NotNull<DataFlowGraph> dfg,
+    AstStatBlock* program,
+    Scope* destScope
+)
+{
+    std::vector<const Scope*> scopes;
+    for (const Scope* current = staleScope; current; current = current->parent.get())
+    {
+        scopes.emplace_back(current);
+    }
+
+    // in reverse order (we need to clone the parents and override defs as we go down the list)
+    for (auto it = scopes.rbegin(); it != scopes.rend(); ++it)
+    {
+        const Scope* curr = *it;
+        // Clone the lvalue types
+        for (const auto& [def, ty] : curr->lvalueTypes)
+            destScope->lvalueTypes[def] = Luau::clone(ty, *destArena, cloneState);
+        // Clone the rvalueRefinements
+        for (const auto& [def, ty] : curr->rvalueRefinements)
+            destScope->rvalueRefinements[def] = Luau::clone(ty, *destArena, cloneState);
+        for (const auto& [n, m] : curr->importedTypeBindings)
+        {
+            std::unordered_map<Name, TypeFun> importedBindingTypes;
+            for (const auto& [v, tf] : m)
+                importedBindingTypes[v] = Luau::clone(tf, *destArena, cloneState);
+            destScope->importedTypeBindings[n] = m;
+        }
+
+        // Finally, clone up the bindings
+        for (const auto& [s, b] : curr->bindings)
+        {
+            destScope->bindings[s] = Luau::clone(b, *destArena, cloneState);
+        }
+    }
+
+    // The above code associates defs with TypeId's in the scope
+    // so that lookup to locals will succeed.
+    MixedModeIncrementalTCDefFinder finder;
+    program->visit(&finder);
+    std::vector<std::pair<AstLocal*, AstExpr*>> locals = std::move(finder.referencedLocalDefs);
+    for (auto [loc, expr] : locals)
+    {
+        if (std::optional<Binding> binding = staleScope->linearSearchForBinding(loc->name.value, true))
+        {
+            destScope->lvalueTypes[dfg->getDef(expr)] = Luau::clone(binding->typeId, *destArena, cloneState);
+        }
+    }
+    return;
+}
+
 static FrontendModuleResolver& getModuleResolver(Frontend& frontend, std::optional<FrontendOptions> options)
 {
     if (FFlag::LuauSolverV2 || !options)
@@ -200,7 +296,7 @@ ScopePtr findClosestScope(const ModulePtr& module, const AstStat* nearestStateme
     return closest;
 }
 
-FragmentParseResult parseFragment(
+std::optional<FragmentParseResult> parseFragment(
     const SourceModule& srcModule,
     std::string_view src,
     const Position& cursorPos,
@@ -245,6 +341,9 @@ FragmentParseResult parseFragment(
     opts.captureComments = true;
     opts.parseFragment = FragmentParseResumeSettings{std::move(result.localMap), std::move(result.localStack), startPos};
     ParseResult p = Luau::Parser::parse(srcStart, parseLength, *nameTbl, *fragmentResult.alloc.get(), opts);
+    // This means we threw a ParseError and we should decline to offer autocomplete here.
+    if (p.root == nullptr)
+        return std::nullopt;
 
     std::vector<AstNode*> fabricatedAncestry = std::move(result.ancestry);
 
@@ -258,16 +357,39 @@ FragmentParseResult parseFragment(
     fragmentResult.root = std::move(p.root);
     fragmentResult.ancestry = std::move(fabricatedAncestry);
     fragmentResult.nearestStatement = nearestStatement;
+    fragmentResult.commentLocations = std::move(p.commentLocations);
     return fragmentResult;
 }
 
+ModulePtr cloneModule(CloneState& cloneState, const ModulePtr& source, std::unique_ptr<Allocator> alloc)
+{
+    freeze(source->internalTypes);
+    freeze(source->interfaceTypes);
+    ModulePtr incremental = std::make_shared<Module>();
+    incremental->name = source->name;
+    incremental->humanReadableName = source->humanReadableName;
+    incremental->allocator = std::move(alloc);
+    //  Clone types
+    cloneModuleMap(incremental->internalTypes, cloneState, source->astTypes, incremental->astTypes);
+    cloneModuleMap(incremental->internalTypes, cloneState, source->astTypePacks, incremental->astTypePacks);
+    cloneModuleMap(incremental->internalTypes, cloneState, source->astExpectedTypes, incremental->astExpectedTypes);
+
+    cloneModuleMap(incremental->internalTypes, cloneState, source->astOverloadResolvedTypes, incremental->astOverloadResolvedTypes);
+
+    cloneModuleMap(incremental->internalTypes, cloneState, source->astForInNextTypes, incremental->astForInNextTypes);
+
+    copyModuleMap(incremental->astScopes, source->astScopes);
+
+    return incremental;
+}
+
 ModulePtr copyModule(const ModulePtr& result, std::unique_ptr<Allocator> alloc)
 {
-    freeze(result->internalTypes);
-    freeze(result->interfaceTypes);
     ModulePtr incrementalModule = std::make_shared<Module>();
     incrementalModule->name = result->name;
-    incrementalModule->humanReadableName = result->humanReadableName;
+    incrementalModule->humanReadableName = "Incremental$" + result->humanReadableName;
+    incrementalModule->internalTypes.owningModule = incrementalModule.get();
+    incrementalModule->interfaceTypes.owningModule = incrementalModule.get();
     incrementalModule->allocator = std::move(alloc);
     // Don't need to keep this alive (it's already on the source module)
     copyModuleVec(incrementalModule->scopes, result->scopes);
@@ -286,21 +408,6 @@ ModulePtr copyModule(const ModulePtr& result, std::unique_ptr<Allocator> alloc)
     return incrementalModule;
 }
 
-struct MixedModeIncrementalTCDefFinder : public AstVisitor
-{
-    bool visit(AstExprLocal* local) override
-    {
-        referencedLocalDefs.push_back({local->local, local});
-        return true;
-    }
-
-    // ast defs is just a mapping from expr -> def in general
-    // will get built up by the dfg builder
-
-    // localDefs, we need to copy over
-    std::vector<std::pair<AstLocal*, AstExpr*>> referencedLocalDefs;
-};
-
 void mixedModeCompatibility(
     const ScopePtr& bottomScopeStale,
     const ScopePtr& myFakeScope,
@@ -339,7 +446,9 @@ FragmentTypeCheckResult typecheckFragment_(
 {
     freeze(stale->internalTypes);
     freeze(stale->interfaceTypes);
-    ModulePtr incrementalModule = copyModule(stale, std::move(astAllocator));
+    CloneState cloneState{frontend.builtinTypes};
+    ModulePtr incrementalModule =
+        FFlag::LuauCloneIncrementalModule ? cloneModule(cloneState, stale, std::move(astAllocator)) : copyModule(stale, std::move(astAllocator));
     incrementalModule->checkedInNewSolver = true;
     unfreeze(incrementalModule->internalTypes);
     unfreeze(incrementalModule->interfaceTypes);
@@ -366,7 +475,8 @@ FragmentTypeCheckResult typecheckFragment_(
     TypeFunctionRuntime typeFunctionRuntime(iceHandler, NotNull{&limits});
 
     /// Create a DataFlowGraph just for the surrounding context
-    auto dfg = DataFlowGraphBuilder::build(root, iceHandler);
+    DataFlowGraph dfg = DataFlowGraphBuilder::build(root, NotNull{&incrementalModule->defArena}, NotNull{&incrementalModule->keyArena}, iceHandler);
+
     SimplifierPtr simplifier = newSimplifier(NotNull{&incrementalModule->internalTypes}, frontend.builtinTypes);
 
     FrontendModuleResolver& resolver = getModuleResolver(frontend, opts);
@@ -386,25 +496,34 @@ FragmentTypeCheckResult typecheckFragment_(
         NotNull{&dfg},
         {}
     };
+    std::shared_ptr<Scope> freshChildOfNearestScope = nullptr;
+    if (FFlag::LuauCloneIncrementalModule)
+    {
+        freshChildOfNearestScope = std::make_shared<Scope>(closestScope);
+        incrementalModule->scopes.emplace_back(root->location, freshChildOfNearestScope);
+        cg.rootScope = freshChildOfNearestScope.get();
 
-    cg.rootScope = stale->getModuleScope().get();
-    // Any additions to the scope must occur in a fresh scope
-    auto freshChildOfNearestScope = std::make_shared<Scope>(closestScope);
-    incrementalModule->scopes.emplace_back(root->location, freshChildOfNearestScope);
-
-    // Update freshChildOfNearestScope with the appropriate lvalueTypes
-    mixedModeCompatibility(closestScope, freshChildOfNearestScope, stale, NotNull{&dfg}, root);
-
-    // closest Scope -> children = { ...., freshChildOfNearestScope}
-    // We need to trim nearestChild from the scope hierarcy
-    closestScope->children.push_back(NotNull{freshChildOfNearestScope.get()});
-    // Visit just the root - we know the scope it should be in
-    cg.visitFragmentRoot(freshChildOfNearestScope, root);
-    // Trim nearestChild from the closestScope
-    Scope* back = closestScope->children.back().get();
-    LUAU_ASSERT(back == freshChildOfNearestScope.get());
-    closestScope->children.pop_back();
-
+        cloneAndSquashScopes(
+            cloneState, closestScope.get(), stale, NotNull{&incrementalModule->internalTypes}, NotNull{&dfg}, root, freshChildOfNearestScope.get()
+        );
+        cg.visitFragmentRoot(freshChildOfNearestScope, root);
+    }
+    else
+    {
+        // Any additions to the scope must occur in a fresh scope
+        cg.rootScope = stale->getModuleScope().get();
+        freshChildOfNearestScope = std::make_shared<Scope>(closestScope);
+        incrementalModule->scopes.emplace_back(root->location, freshChildOfNearestScope);
+        mixedModeCompatibility(closestScope, freshChildOfNearestScope, stale, NotNull{&dfg}, root);
+        // closest Scope -> children = { ...., freshChildOfNearestScope}
+        // We need to trim nearestChild from the scope hierarcy
+        closestScope->children.emplace_back(freshChildOfNearestScope.get());
+        cg.visitFragmentRoot(freshChildOfNearestScope, root);
+        // Trim nearestChild from the closestScope
+        Scope* back = closestScope->children.back().get();
+        LUAU_ASSERT(back == freshChildOfNearestScope.get());
+        closestScope->children.pop_back();
+    }
 
     /// Initialize the constraint solver and run it
     ConstraintSolver cs{
@@ -444,7 +563,7 @@ FragmentTypeCheckResult typecheckFragment_(
 }
 
 
-FragmentTypeCheckResult typecheckFragment(
+std::pair<FragmentTypeCheckStatus, FragmentTypeCheckResult> typecheckFragment(
     Frontend& frontend,
     const ModuleName& moduleName,
     const Position& cursorPos,
@@ -453,6 +572,13 @@ FragmentTypeCheckResult typecheckFragment(
     std::optional<Position> fragmentEndPosition
 )
 {
+
+    if (FFlag::LuauBetterReverseDependencyTracking)
+    {
+        if (!frontend.allModuleDependenciesValid(moduleName, opts && opts->forAutocomplete))
+            return {FragmentTypeCheckStatus::SkipAutocomplete, {}};
+    }
+
     const SourceModule* sourceModule = frontend.getSourceModule(moduleName);
     if (!sourceModule)
     {
@@ -468,13 +594,30 @@ FragmentTypeCheckResult typecheckFragment(
         return {};
     }
 
-    FragmentParseResult parseResult = parseFragment(*sourceModule, src, cursorPos, fragmentEndPosition);
+    if (FFlag::LuauIncrementalAutocompleteBugfixes && FFlag::LuauReferenceAllocatorInNewSolver)
+    {
+        if (sourceModule->allocator.get() != module->allocator.get())
+        {
+            return {FragmentTypeCheckStatus::SkipAutocomplete, {}};
+        }
+    }
+
+    auto tryParse = parseFragment(*sourceModule, src, cursorPos, fragmentEndPosition);
+
+    if (!tryParse)
+        return {FragmentTypeCheckStatus::SkipAutocomplete, {}};
+
+    FragmentParseResult& parseResult = *tryParse;
+
+    if (isWithinComment(parseResult.commentLocations, fragmentEndPosition.value_or(cursorPos)))
+        return {FragmentTypeCheckStatus::SkipAutocomplete, {}};
+
     FrontendOptions frontendOptions = opts.value_or(frontend.options);
     const ScopePtr& closestScope = findClosestScope(module, parseResult.nearestStatement);
     FragmentTypeCheckResult result =
         typecheckFragment_(frontend, parseResult.root, module, closestScope, cursorPos, std::move(parseResult.alloc), frontendOptions);
     result.ancestry = std::move(parseResult.ancestry);
-    return result;
+    return {FragmentTypeCheckStatus::Success, result};
 }
 
 
@@ -498,7 +641,14 @@ FragmentAutocompleteResult fragmentAutocomplete(
         return {};
     }
 
-    auto tcResult = typecheckFragment(frontend, moduleName, cursorPosition, opts, src, fragmentEndPosition);
+    // If the cursor is within a comment in the stale source module we should avoid providing a recommendation
+    if (isWithinComment(*sourceModule, fragmentEndPosition.value_or(cursorPosition)))
+        return {};
+
+    auto [tcStatus, tcResult] = typecheckFragment(frontend, moduleName, cursorPosition, opts, src, fragmentEndPosition);
+    if (tcStatus == FragmentTypeCheckStatus::SkipAutocomplete)
+        return {};
+
     auto globalScope = (opts && opts->forAutocomplete) ? frontend.globalsForAutocomplete.globalScope.get() : frontend.globals.globalScope.get();
 
     TypeArena arenaForFragmentAutocomplete;

Analysis/src/Frontend.cpp

@@ -13,6 +13,7 @@
 #include "Luau/EqSatSimplification.h"
 #include "Luau/FileResolver.h"
 #include "Luau/NonStrictTypeChecker.h"
+#include "Luau/NotNull.h"
 #include "Luau/Parser.h"
 #include "Luau/Scope.h"
 #include "Luau/StringUtils.h"
@@ -38,7 +39,6 @@ LUAU_FASTINT(LuauTypeInferRecursionLimit)
 LUAU_FASTINT(LuauTarjanChildLimit)
 LUAU_FASTFLAG(LuauInferInNoCheckMode)
 LUAU_FASTFLAGVARIABLE(LuauKnowsTheDataModel3)
-LUAU_FASTFLAGVARIABLE(LuauStoreCommentsForDefinitionFiles)
 LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAGVARIABLE(DebugLuauLogSolverToJson)
 LUAU_FASTFLAGVARIABLE(DebugLuauLogSolverToJsonFile)
@@ -47,9 +47,14 @@ LUAU_FASTFLAGVARIABLE(DebugLuauForceStrictMode)
 LUAU_FASTFLAGVARIABLE(DebugLuauForceNonStrictMode)
 LUAU_DYNAMIC_FASTFLAGVARIABLE(LuauRunCustomModuleChecks, false)
 
+LUAU_FASTFLAGVARIABLE(LuauBetterReverseDependencyTracking)
+
 LUAU_FASTFLAG(StudioReportLuauAny2)
 LUAU_FASTFLAGVARIABLE(LuauStoreSolverTypeOnModule)
 
+LUAU_FASTFLAGVARIABLE(LuauReferenceAllocatorInNewSolver)
+LUAU_FASTFLAGVARIABLE(LuauSelectivelyRetainDFGArena)
+
 namespace Luau
 {
 
@@ -135,7 +140,7 @@ static ParseResult parseSourceForModule(std::string_view source, Luau::SourceMod
     sourceModule.root = parseResult.root;
     sourceModule.mode = Mode::Definition;
 
-    if (FFlag::LuauStoreCommentsForDefinitionFiles && options.captureComments)
+    if (options.captureComments)
     {
         sourceModule.hotcomments = parseResult.hotcomments;
         sourceModule.commentLocations = parseResult.commentLocations;
@@ -817,6 +822,16 @@ bool Frontend::parseGraph(
             topseen = Permanent;
 
             buildQueue.push_back(top->name);
+
+            if (FFlag::LuauBetterReverseDependencyTracking)
+            {
+                // at this point we know all valid dependencies are processed into SourceNodes
+                for (const ModuleName& dep : top->requireSet)
+                {
+                    if (auto it = sourceNodes.find(dep); it != sourceNodes.end())
+                        it->second->dependents.insert(top->name);
+                }
+            }
         }
         else
         {
@@ -1046,6 +1061,11 @@ void Frontend::checkBuildQueueItem(BuildQueueItem& item)
         freeze(module->interfaceTypes);
 
         module->internalTypes.clear();
+        if (FFlag::LuauSelectivelyRetainDFGArena)
+        {
+            module->defArena.allocator.clear();
+            module->keyArena.allocator.clear();
+        }
 
         module->astTypes.clear();
         module->astTypePacks.clear();
@@ -1099,15 +1119,49 @@ void Frontend::recordItemResult(const BuildQueueItem& item)
     if (item.exception)
         std::rethrow_exception(item.exception);
 
-    if (item.options.forAutocomplete)
+    if (FFlag::LuauBetterReverseDependencyTracking)
     {
-        moduleResolverForAutocomplete.setModule(item.name, item.module);
-        item.sourceNode->dirtyModuleForAutocomplete = false;
+        bool replacedModule = false;
+        if (item.options.forAutocomplete)
+        {
+            replacedModule = moduleResolverForAutocomplete.setModule(item.name, item.module);
+            item.sourceNode->dirtyModuleForAutocomplete = false;
+        }
+        else
+        {
+            replacedModule = moduleResolver.setModule(item.name, item.module);
+            item.sourceNode->dirtyModule = false;
+        }
+
+        if (replacedModule)
+        {
+            LUAU_TIMETRACE_SCOPE("Frontend::invalidateDependentModules", "Frontend");
+            LUAU_TIMETRACE_ARGUMENT("name", item.name.c_str());
+            traverseDependents(
+                item.name,
+                [forAutocomplete = item.options.forAutocomplete](SourceNode& sourceNode)
+                {
+                    bool traverseSubtree = !sourceNode.hasInvalidModuleDependency(forAutocomplete);
+                    sourceNode.setInvalidModuleDependency(true, forAutocomplete);
+                    return traverseSubtree;
+                }
+            );
+        }
+
+        item.sourceNode->setInvalidModuleDependency(false, item.options.forAutocomplete);
     }
     else
     {
-        moduleResolver.setModule(item.name, item.module);
-        item.sourceNode->dirtyModule = false;
+        if (item.options.forAutocomplete)
+        {
+            moduleResolverForAutocomplete.setModule(item.name, item.module);
+            item.sourceNode->dirtyModuleForAutocomplete = false;
+        }
+        else
+        {
+            moduleResolver.setModule(item.name, item.module);
+            item.sourceNode->dirtyModule = false;
+        }
     }
 
     stats.timeCheck += item.stats.timeCheck;
@@ -1144,6 +1198,13 @@ ScopePtr Frontend::getModuleEnvironment(const SourceModule& module, const Config
     return result;
 }
 
+bool Frontend::allModuleDependenciesValid(const ModuleName& name, bool forAutocomplete) const
+{
+    LUAU_ASSERT(FFlag::LuauBetterReverseDependencyTracking);
+    auto it = sourceNodes.find(name);
+    return it != sourceNodes.end() && !it->second->hasInvalidModuleDependency(forAutocomplete);
+}
+
 bool Frontend::isDirty(const ModuleName& name, bool forAutocomplete) const
 {
     auto it = sourceNodes.find(name);
@@ -1158,16 +1219,80 @@ bool Frontend::isDirty(const ModuleName& name, bool forAutocomplete) const
  */
 void Frontend::markDirty(const ModuleName& name, std::vector<ModuleName>* markedDirty)
 {
+    LUAU_TIMETRACE_SCOPE("Frontend::markDirty", "Frontend");
+    LUAU_TIMETRACE_ARGUMENT("name", name.c_str());
+
+    if (FFlag::LuauBetterReverseDependencyTracking)
+    {
+        traverseDependents(
+            name,
+            [markedDirty](SourceNode& sourceNode)
+            {
+                if (markedDirty)
+                    markedDirty->push_back(sourceNode.name);
+
+                if (sourceNode.dirtySourceModule && sourceNode.dirtyModule && sourceNode.dirtyModuleForAutocomplete)
+                    return false;
+
+                sourceNode.dirtySourceModule = true;
+                sourceNode.dirtyModule = true;
+                sourceNode.dirtyModuleForAutocomplete = true;
+
+                return true;
+            }
+        );
+    }
+    else
+    {
+        if (sourceNodes.count(name) == 0)
+            return;
+
+        std::unordered_map<ModuleName, std::vector<ModuleName>> reverseDeps;
+        for (const auto& module : sourceNodes)
+        {
+            for (const auto& dep : module.second->requireSet)
+                reverseDeps[dep].push_back(module.first);
+        }
+
+        std::vector<ModuleName> queue{name};
+
+        while (!queue.empty())
+        {
+            ModuleName next = std::move(queue.back());
+            queue.pop_back();
+
+            LUAU_ASSERT(sourceNodes.count(next) > 0);
+            SourceNode& sourceNode = *sourceNodes[next];
+
+            if (markedDirty)
+                markedDirty->push_back(next);
+
+            if (sourceNode.dirtySourceModule && sourceNode.dirtyModule && sourceNode.dirtyModuleForAutocomplete)
+                continue;
+
+            sourceNode.dirtySourceModule = true;
+            sourceNode.dirtyModule = true;
+            sourceNode.dirtyModuleForAutocomplete = true;
+
+            if (0 == reverseDeps.count(next))
+                continue;
+
+            sourceModules.erase(next);
+
+            const std::vector<ModuleName>& dependents = reverseDeps[next];
+            queue.insert(queue.end(), dependents.begin(), dependents.end());
+        }
+    }
+}
+
+void Frontend::traverseDependents(const ModuleName& name, std::function<bool(SourceNode&)> processSubtree)
+{
+    LUAU_ASSERT(FFlag::LuauBetterReverseDependencyTracking);
+    LUAU_TIMETRACE_SCOPE("Frontend::traverseDependents", "Frontend");
+
     if (sourceNodes.count(name) == 0)
         return;
 
-    std::unordered_map<ModuleName, std::vector<ModuleName>> reverseDeps;
-    for (const auto& module : sourceNodes)
-    {
-        for (const auto& dep : module.second->requireSet)
-            reverseDeps[dep].push_back(module.first);
-    }
-
     std::vector<ModuleName> queue{name};
 
     while (!queue.empty())
@@ -1178,22 +1303,10 @@ void Frontend::markDirty(const ModuleName& name, std::vector<ModuleName>* marked
         LUAU_ASSERT(sourceNodes.count(next) > 0);
         SourceNode& sourceNode = *sourceNodes[next];
 
-        if (markedDirty)
-            markedDirty->push_back(next);
-
-        if (sourceNode.dirtySourceModule && sourceNode.dirtyModule && sourceNode.dirtyModuleForAutocomplete)
+        if (!processSubtree(sourceNode))
             continue;
 
-        sourceNode.dirtySourceModule = true;
-        sourceNode.dirtyModule = true;
-        sourceNode.dirtyModuleForAutocomplete = true;
-
-        if (0 == reverseDeps.count(next))
-            continue;
-
-        sourceModules.erase(next);
-
-        const std::vector<ModuleName>& dependents = reverseDeps[next];
+        const Set<ModuleName>& dependents = sourceNode.dependents;
         queue.insert(queue.end(), dependents.begin(), dependents.end());
     }
 }
@@ -1317,6 +1430,11 @@ ModulePtr check(
     result->mode = mode;
     result->internalTypes.owningModule = result.get();
     result->interfaceTypes.owningModule = result.get();
+    if (FFlag::LuauReferenceAllocatorInNewSolver)
+    {
+        result->allocator = sourceModule.allocator;
+        result->names = sourceModule.names;
+    }
 
     iceHandler->moduleName = sourceModule.name;
 
@@ -1331,7 +1449,7 @@ ModulePtr check(
         }
     }
 
-    DataFlowGraph dfg = DataFlowGraphBuilder::build(sourceModule.root, iceHandler);
+    DataFlowGraph dfg = DataFlowGraphBuilder::build(sourceModule.root, NotNull{&result->defArena}, NotNull{&result->keyArena}, iceHandler);
 
     UnifierSharedState unifierState{iceHandler};
     unifierState.counters.recursionLimit = FInt::LuauTypeInferRecursionLimit;
@@ -1427,6 +1545,7 @@ ModulePtr check(
         case Mode::Nonstrict:
             Luau::checkNonStrict(
                 builtinTypes,
+                NotNull{simplifier.get()},
                 NotNull{&typeFunctionRuntime},
                 iceHandler,
                 NotNull{&unifierState},
@@ -1440,7 +1559,14 @@ ModulePtr check(
             // fallthrough intentional
         case Mode::Strict:
             Luau::check(
-                builtinTypes, NotNull{&typeFunctionRuntime}, NotNull{&unifierState}, NotNull{&limits}, logger.get(), sourceModule, result.get()
+                builtinTypes,
+                NotNull{simplifier.get()},
+                NotNull{&typeFunctionRuntime},
+                NotNull{&unifierState},
+                NotNull{&limits},
+                logger.get(),
+                sourceModule,
+                result.get()
             );
             break;
         case Mode::NoCheck:
@@ -1622,6 +1748,17 @@ std::pair<SourceNode*, SourceModule*> Frontend::getSourceNode(const ModuleName&
 
     sourceNode->name = sourceModule->name;
     sourceNode->humanReadableName = sourceModule->humanReadableName;
+
+    if (FFlag::LuauBetterReverseDependencyTracking)
+    {
+        // clear all prior dependents. we will re-add them after parsing the rest of the graph 
+        for (const auto& [moduleName, _] : sourceNode->requireLocations)
+        {
+            if (auto depIt = sourceNodes.find(moduleName); depIt != sourceNodes.end())
+                depIt->second->dependents.erase(sourceNode->name);
+        }
+    }
+
     sourceNode->requireSet.clear();
     sourceNode->requireLocations.clear();
     sourceNode->dirtySourceModule = false;
@@ -1743,11 +1880,21 @@ std::string FrontendModuleResolver::getHumanReadableModuleName(const ModuleName&
     return frontend->fileResolver->getHumanReadableModuleName(moduleName);
 }
 
-void FrontendModuleResolver::setModule(const ModuleName& moduleName, ModulePtr module)
+bool FrontendModuleResolver::setModule(const ModuleName& moduleName, ModulePtr module)
 {
     std::scoped_lock lock(moduleMutex);
 
-    modules[moduleName] = std::move(module);
+    if (FFlag::LuauBetterReverseDependencyTracking)
+    {
+        bool replaced = modules.count(moduleName) > 0;
+        modules[moduleName] = std::move(module);
+        return replaced;
+    }
+    else
+    {
+        modules[moduleName] = std::move(module);
+        return false;
+    }
 }
 
 void FrontendModuleResolver::clearModules()

Analysis/src/Generalization.cpp

@@ -10,12 +10,14 @@
 #include "Luau/VisitType.h"
 
 LUAU_FASTFLAG(LuauAutocompleteRefactorsForIncrementalAutocomplete)
+LUAU_FASTFLAGVARIABLE(LuauGeneralizationRemoveRecursiveUpperBound)
 
 namespace Luau
 {
 
 struct MutatingGeneralizer : TypeOnceVisitor
 {
+    NotNull<TypeArena> arena;
     NotNull<BuiltinTypes> builtinTypes;
 
     NotNull<Scope> scope;
@@ -29,6 +31,7 @@ struct MutatingGeneralizer : TypeOnceVisitor
     bool avoidSealingTables = false;
 
     MutatingGeneralizer(
+        NotNull<TypeArena> arena,
         NotNull<BuiltinTypes> builtinTypes,
         NotNull<Scope> scope,
         NotNull<DenseHashSet<TypeId>> cachedTypes,
@@ -37,6 +40,7 @@ struct MutatingGeneralizer : TypeOnceVisitor
         bool avoidSealingTables
     )
         : TypeOnceVisitor(/* skipBoundTypes */ true)
+        , arena(arena)
         , builtinTypes(builtinTypes)
         , scope(scope)
         , cachedTypes(cachedTypes)
@@ -229,6 +233,53 @@ struct MutatingGeneralizer : TypeOnceVisitor
         else
         {
             TypeId ub = follow(ft->upperBound);
+            if (FFlag::LuauGeneralizationRemoveRecursiveUpperBound)
+            {
+
+                // If the upper bound is a union type or an intersection type,
+                // and one of it's members is the free type we're
+                // generalizing, don't include it in the upper bound. For a
+                // free type such as:
+                //
+                //  t1 where t1 = D <: 'a <: (A | B | C | t1)
+                //
+                // Naively replacing it with it's upper bound creates:
+                //
+                //  t1 where t1 = A | B | C | t1
+                //
+                // It makes sense to just optimize this and exclude the
+                // recursive component by semantic subtyping rules.
+
+                if (auto itv = get<IntersectionType>(ub))
+                {
+                    std::vector<TypeId> newIds;
+                    newIds.reserve(itv->parts.size());
+                    for (auto part : itv)
+                    {
+                        if (part != ty)
+                            newIds.push_back(part);
+                    }
+                    if (newIds.size() == 1)
+                        ub = newIds[0];
+                    else if (newIds.size() > 0)
+                        ub = arena->addType(IntersectionType{std::move(newIds)});
+                }
+                else if (auto utv = get<UnionType>(ub))
+                {
+                    std::vector<TypeId> newIds;
+                    newIds.reserve(utv->options.size());
+                    for (auto part : utv)
+                    {
+                        if (part != ty)
+                            newIds.push_back(part);
+                    }
+                    if (newIds.size() == 1)
+                        ub = newIds[0];
+                    else if (newIds.size() > 0)
+                        ub = arena->addType(UnionType{std::move(newIds)});
+                }
+            }
+
             if (FreeType* upperFree = getMutable<FreeType>(ub); upperFree && upperFree->lowerBound == ty)
                 upperFree->lowerBound = builtinTypes->neverType;
             else
@@ -926,7 +977,8 @@ struct TypeCacher : TypeOnceVisitor
         return false;
     }
 
-    bool visit(TypePackId tp, const BoundTypePack& btp) override {
+    bool visit(TypePackId tp, const BoundTypePack& btp) override
+    {
         traverse(btp.boundTo);
         if (isUncacheable(btp.boundTo))
             markUncacheable(tp);
@@ -969,7 +1021,7 @@ std::optional<TypeId> generalize(
     FreeTypeSearcher fts{scope, cachedTypes};
     fts.traverse(ty);
 
-    MutatingGeneralizer gen{builtinTypes, scope, cachedTypes, std::move(fts.positiveTypes), std::move(fts.negativeTypes), avoidSealingTables};
+    MutatingGeneralizer gen{arena, builtinTypes, scope, cachedTypes, std::move(fts.positiveTypes), std::move(fts.negativeTypes), avoidSealingTables};
 
     gen.traverse(ty);
 

Analysis/src/Instantiation.cpp

@@ -11,6 +11,7 @@
 #include <algorithm>
 
 LUAU_FASTFLAG(LuauSolverV2)
+LUAU_FASTFLAG(LuauFreeTypesMustHaveBounds)
 
 namespace Luau
 {
@@ -61,9 +62,7 @@ TypeId Instantiation::clean(TypeId ty)
     LUAU_ASSERT(ftv);
 
     FunctionType clone = FunctionType{level, scope, ftv->argTypes, ftv->retTypes, ftv->definition, ftv->hasSelf};
-    clone.magicFunction = ftv->magicFunction;
-    clone.dcrMagicFunction = ftv->dcrMagicFunction;
-    clone.dcrMagicRefinement = ftv->dcrMagicRefinement;
+    clone.magic = ftv->magic;
     clone.tags = ftv->tags;
     clone.argNames = ftv->argNames;
     TypeId result = addType(std::move(clone));
@@ -165,7 +164,7 @@ TypeId ReplaceGenerics::clean(TypeId ty)
     }
     else
     {
-        return addType(FreeType{scope, level});
+        return FFlag::LuauFreeTypesMustHaveBounds ? arena->freshType(builtinTypes, scope, level) : addType(FreeType{scope, level});
     }
 }
 

Analysis/src/Module.cpp

@@ -15,11 +15,12 @@
 #include <algorithm>
 
 LUAU_FASTFLAG(LuauSolverV2);
+LUAU_FASTFLAGVARIABLE(LuauIncrementalAutocompleteCommentDetection)
 
 namespace Luau
 {
 
-static bool contains(Position pos, Comment comment)
+static bool contains_DEPRECATED(Position pos, Comment comment)
 {
     if (comment.location.contains(pos))
         return true;
@@ -32,7 +33,22 @@ static bool contains(Position pos, Comment comment)
         return false;
 }
 
-static bool isWithinComment(const std::vector<Comment>& commentLocations, Position pos)
+static bool contains(Position pos, Comment comment)
+{
+    if (comment.location.contains(pos))
+        return true;
+    else if (comment.type == Lexeme::BrokenComment && comment.location.begin <= pos) // Broken comments are broken specifically because they don't
+                                                                                     // have an end
+        return true;
+    // comments actually span the whole line - in incremental mode, we could pass a cursor outside of the current parsed comment range span, but it
+    // would still be 'within' the comment So, the cursor must be on the same line and the comment itself must come strictly after the `begin`
+    else if (comment.type == Lexeme::Comment && comment.location.end.line == pos.line && comment.location.begin <= pos)
+        return true;
+    else
+        return false;
+}
+
+bool isWithinComment(const std::vector<Comment>& commentLocations, Position pos)
 {
     auto iter = std::lower_bound(
         commentLocations.begin(),
@@ -40,6 +56,11 @@ static bool isWithinComment(const std::vector<Comment>& commentLocations, Positi
         Comment{Lexeme::Comment, Location{pos, pos}},
         [](const Comment& a, const Comment& b)
         {
+            if (FFlag::LuauIncrementalAutocompleteCommentDetection)
+            {
+                if (a.type == Lexeme::Comment)
+                    return a.location.end.line < b.location.end.line;
+            }
             return a.location.end < b.location.end;
         }
     );
@@ -47,7 +68,7 @@ static bool isWithinComment(const std::vector<Comment>& commentLocations, Positi
     if (iter == commentLocations.end())
         return false;
 
-    if (contains(pos, *iter))
+    if (FFlag::LuauIncrementalAutocompleteCommentDetection ? contains(pos, *iter) : contains_DEPRECATED(pos, *iter))
         return true;
 
     // Due to the nature of std::lower_bound, it is possible that iter points at a comment that ends
@@ -149,9 +170,9 @@ struct ClonePublicInterface : Substitution
                     freety->scope->location,
                     module->name,
                     InternalError{"Free type is escaping its module; please report this bug at "
-                    "https://github.com/luau-lang/luau/issues"}
-                    );
-                    result = builtinTypes->errorRecoveryType();
+                                  "https://github.com/luau-lang/luau/issues"}
+                );
+                result = builtinTypes->errorRecoveryType();
             }
             else if (auto genericty = getMutable<GenericType>(result))
             {
@@ -173,8 +194,8 @@ struct ClonePublicInterface : Substitution
                     ftp->scope->location,
                     module->name,
                     InternalError{"Free type pack is escaping its module; please report this bug at "
-                    "https://github.com/luau-lang/luau/issues"}
-                    );
+                                  "https://github.com/luau-lang/luau/issues"}
+                );
                 clonedTp = builtinTypes->errorRecoveryTypePack();
             }
             else if (auto gtp = getMutable<GenericTypePack>(clonedTp))

Analysis/src/NonStrictTypeChecker.cpp

@@ -19,8 +19,8 @@
 #include <iostream>
 #include <iterator>
 
-LUAU_FASTFLAGVARIABLE(LuauUserTypeFunNonstrict)
 LUAU_FASTFLAGVARIABLE(LuauCountSelfCallsNonstrict)
+LUAU_FASTFLAG(LuauFreeTypesMustHaveBounds)
 
 namespace Luau
 {
@@ -158,6 +158,7 @@ private:
 struct NonStrictTypeChecker
 {
     NotNull<BuiltinTypes> builtinTypes;
+    NotNull<Simplifier> simplifier;
     NotNull<TypeFunctionRuntime> typeFunctionRuntime;
     const NotNull<InternalErrorReporter> ice;
     NotNull<TypeArena> arena;
@@ -174,6 +175,7 @@ struct NonStrictTypeChecker
     NonStrictTypeChecker(
         NotNull<TypeArena> arena,
         NotNull<BuiltinTypes> builtinTypes,
+        NotNull<Simplifier> simplifier,
         NotNull<TypeFunctionRuntime> typeFunctionRuntime,
         const NotNull<InternalErrorReporter> ice,
         NotNull<UnifierSharedState> unifierState,
@@ -182,12 +184,13 @@ struct NonStrictTypeChecker
         Module* module
     )
         : builtinTypes(builtinTypes)
+        , simplifier(simplifier)
         , typeFunctionRuntime(typeFunctionRuntime)
         , ice(ice)
         , arena(arena)
         , module(module)
         , normalizer{arena, builtinTypes, unifierState, /* cache inhabitance */ true}
-        , subtyping{builtinTypes, arena, NotNull(&normalizer), typeFunctionRuntime, ice}
+        , subtyping{builtinTypes, arena, simplifier, NotNull(&normalizer), typeFunctionRuntime, ice}
         , dfg(dfg)
         , limits(limits)
     {
@@ -209,7 +212,7 @@ struct NonStrictTypeChecker
             return *fst;
         else if (auto ftp = get<FreeTypePack>(pack))
         {
-            TypeId result = arena->addType(FreeType{ftp->scope});
+            TypeId result = FFlag::LuauFreeTypesMustHaveBounds ? arena->freshType(builtinTypes, ftp->scope) : arena->addType(FreeType{ftp->scope});
             TypePackId freeTail = arena->addTypePack(FreeTypePack{ftp->scope});
 
             TypePack* resultPack = emplaceTypePack<TypePack>(asMutable(pack));
@@ -232,13 +235,14 @@ struct NonStrictTypeChecker
         if (noTypeFunctionErrors.find(instance))
             return instance;
 
-        ErrorVec errors = reduceTypeFunctions(
-                              instance,
-                              location,
-                              TypeFunctionContext{arena, builtinTypes, stack.back(), NotNull{&normalizer}, typeFunctionRuntime, ice, limits},
-                              true
-        )
-                              .errors;
+        ErrorVec errors =
+            reduceTypeFunctions(
+                instance,
+                location,
+                TypeFunctionContext{arena, builtinTypes, stack.back(), simplifier, NotNull{&normalizer}, typeFunctionRuntime, ice, limits},
+                true
+            )
+                .errors;
 
         if (errors.empty())
             noTypeFunctionErrors.insert(instance);
@@ -424,9 +428,6 @@ struct NonStrictTypeChecker
 
     NonStrictContext visit(AstStatTypeFunction* typeFunc)
     {
-        if (!FFlag::LuauUserTypeFunNonstrict)
-            reportError(GenericError{"This syntax is not supported"}, typeFunc->location);
-
         return {};
     }
 
@@ -888,6 +889,7 @@ private:
 
 void checkNonStrict(
     NotNull<BuiltinTypes> builtinTypes,
+    NotNull<Simplifier> simplifier,
     NotNull<TypeFunctionRuntime> typeFunctionRuntime,
     NotNull<InternalErrorReporter> ice,
     NotNull<UnifierSharedState> unifierState,
@@ -899,7 +901,9 @@ void checkNonStrict(
 {
     LUAU_TIMETRACE_SCOPE("checkNonStrict", "Typechecking");
 
-    NonStrictTypeChecker typeChecker{NotNull{&module->internalTypes}, builtinTypes, typeFunctionRuntime, ice, unifierState, dfg, limits, module};
+    NonStrictTypeChecker typeChecker{
+        NotNull{&module->internalTypes}, builtinTypes, simplifier, typeFunctionRuntime, ice, unifierState, dfg, limits, module
+    };
     typeChecker.visit(sourceModule.root);
     unfreeze(module->interfaceTypes);
     copyErrors(module->errors, module->interfaceTypes, builtinTypes);

Analysis/src/Normalize.cpp

@@ -17,12 +17,11 @@
 
 LUAU_FASTFLAGVARIABLE(DebugLuauCheckNormalizeInvariant)
 
-LUAU_FASTINTVARIABLE(LuauNormalizeCacheLimit, 100000);
-LUAU_FASTFLAG(LuauSolverV2);
-
+LUAU_FASTINTVARIABLE(LuauNormalizeCacheLimit, 100000)
 LUAU_FASTINTVARIABLE(LuauNormalizeIntersectionLimit, 200)
-LUAU_FASTFLAGVARIABLE(LuauNormalizationTracksCyclicPairsThroughInhabitance);
-LUAU_FASTFLAGVARIABLE(LuauIntersectNormalsNeedsToTrackResourceLimits);
+LUAU_FASTFLAG(LuauSolverV2)
+LUAU_FASTFLAGVARIABLE(LuauFixInfiniteRecursionInNormalization)
+LUAU_FASTFLAGVARIABLE(LuauFixNormalizedIntersectionOfNegatedClass)
 
 namespace Luau
 {
@@ -1809,7 +1808,8 @@ NormalizationResult Normalizer::unionNormalWithTy(
     }
     else if (get<UnknownType>(here.tops))
         return NormalizationResult::True;
-    else if (get<GenericType>(there) || get<FreeType>(there) || get<BlockedType>(there) || get<PendingExpansionType>(there) || get<TypeFunctionInstanceType>(there))
+    else if (get<GenericType>(there) || get<FreeType>(there) || get<BlockedType>(there) || get<PendingExpansionType>(there) ||
+             get<TypeFunctionInstanceType>(there))
     {
         if (tyvarIndex(there) <= ignoreSmallerTyvars)
             return NormalizationResult::True;
@@ -2284,9 +2284,24 @@ void Normalizer::intersectClassesWithClass(NormalizedClassType& heres, TypeId th
         else if (isSubclass(there, hereTy))
         {
             TypeIds negations = std::move(hereNegations);
+            bool emptyIntersectWithNegation = false;
 
             for (auto nIt = negations.begin(); nIt != negations.end();)
             {
+                if (FFlag::LuauFixNormalizedIntersectionOfNegatedClass && isSubclass(there, *nIt))
+                {
+                    // Hitting this block means that the incoming class is a
+                    // subclass of this type, _and_ one of its negations is a
+                    // superclass of this type, e.g.:
+                    //
+                    //  Dog & ~Animal
+                    //
+                    // Clearly this intersects to never, so we mark this class as 
+                    // being removed from the normalized class type.
+                    emptyIntersectWithNegation = true;
+                    break;
+                }
+
                 if (!isSubclass(*nIt, there))
                 {
                     nIt = negations.erase(nIt);
@@ -2299,7 +2314,8 @@ void Normalizer::intersectClassesWithClass(NormalizedClassType& heres, TypeId th
 
             it = heres.ordering.erase(it);
             heres.classes.erase(hereTy);
-            heres.pushPair(there, std::move(negations));
+            if (!emptyIntersectWithNegation)
+                heres.pushPair(there, std::move(negations));
             break;
         }
         // If the incoming class is a superclass of the current class, we don't
@@ -2584,11 +2600,31 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
                 {
                     if (tprop.readTy.has_value())
                     {
-                        // if the intersection of the read types of a property is uninhabited, the whole table is `never`.
-                        // We've seen these table prop elements before and we're about to ask if their intersection
-                        // is inhabited
-                        if (FFlag::LuauNormalizationTracksCyclicPairsThroughInhabitance)
+                        if (FFlag::LuauFixInfiniteRecursionInNormalization)
                         {
+                            TypeId ty = simplifyIntersection(builtinTypes, NotNull{arena}, *hprop.readTy, *tprop.readTy).result;
+
+                            // If any property is going to get mapped to `never`, we can just call the entire table `never`.
+                            // Since this check is syntactic, we may sometimes miss simplifying tables with complex uninhabited properties.
+                            // Prior versions of this code attempted to do this semantically using the normalization machinery, but this
+                            // mistakenly causes infinite loops when giving more complex recursive table types. As it stands, this approach
+                            // will continue to scale as simplification is improved, but we may wish to reintroduce the semantic approach
+                            // once we have revisited the usage of seen sets systematically (and possibly with some additional guarding to recognize
+                            // when types are infinitely-recursive with non-pointer identical instances of them, or some guard to prevent that
+                            // construction altogether). See also: `gh1632_no_infinite_recursion_in_normalization`
+                            if (get<NeverType>(ty))
+                                return {builtinTypes->neverType};
+
+                            prop.readTy = ty;
+                            hereSubThere &= (ty == hprop.readTy);
+                            thereSubHere &= (ty == tprop.readTy);
+                        }
+                        else
+                        {
+                            // if the intersection of the read types of a property is uninhabited, the whole table is `never`.
+                            // We've seen these table prop elements before and we're about to ask if their intersection
+                            // is inhabited
+
                             auto pair1 = std::pair{*hprop.readTy, *tprop.readTy};
                             auto pair2 = std::pair{*tprop.readTy, *hprop.readTy};
                             if (seenTablePropPairs.contains(pair1) || seenTablePropPairs.contains(pair2))
@@ -2603,6 +2639,8 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
                                 seenTablePropPairs.insert(pair2);
                             }
 
+                            // FIXME(ariel): this is being added in a flag removal, so not changing the semantics here, but worth noting that this
+                            // fresh `seenSet` is definitely a bug. we already have `seenSet` from the parameter that _should_ have been used here.
                             Set<TypeId> seenSet{nullptr};
                             NormalizationResult res = isIntersectionInhabited(*hprop.readTy, *tprop.readTy, seenTablePropPairs, seenSet);
 
@@ -2616,34 +2654,6 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
                             hereSubThere &= (ty == hprop.readTy);
                             thereSubHere &= (ty == tprop.readTy);
                         }
-                        else
-                        {
-
-                            if (seenSet.contains(*hprop.readTy) && seenSet.contains(*tprop.readTy))
-                            {
-                                seenSet.erase(*hprop.readTy);
-                                seenSet.erase(*tprop.readTy);
-                                return {builtinTypes->neverType};
-                            }
-                            else
-                            {
-                                seenSet.insert(*hprop.readTy);
-                                seenSet.insert(*tprop.readTy);
-                            }
-
-                            NormalizationResult res = isIntersectionInhabited(*hprop.readTy, *tprop.readTy);
-
-                            seenSet.erase(*hprop.readTy);
-                            seenSet.erase(*tprop.readTy);
-
-                            if (NormalizationResult::True != res)
-                                return {builtinTypes->neverType};
-
-                            TypeId ty = simplifyIntersection(builtinTypes, NotNull{arena}, *hprop.readTy, *tprop.readTy).result;
-                            prop.readTy = ty;
-                            hereSubThere &= (ty == hprop.readTy);
-                            thereSubHere &= (ty == tprop.readTy);
-                        }
                     }
                     else
                     {
@@ -3042,12 +3052,9 @@ NormalizationResult Normalizer::intersectTyvarsWithTy(
 // See above for an explaination of `ignoreSmallerTyvars`.
 NormalizationResult Normalizer::intersectNormals(NormalizedType& here, const NormalizedType& there, int ignoreSmallerTyvars)
 {
-    if (FFlag::LuauIntersectNormalsNeedsToTrackResourceLimits)
-    {
-        RecursionCounter _rc(&sharedState->counters.recursionCount);
-        if (!withinResourceLimits())
-            return NormalizationResult::HitLimits;
-    }
+    RecursionCounter _rc(&sharedState->counters.recursionCount);
+    if (!withinResourceLimits())
+        return NormalizationResult::HitLimits;
 
     if (!get<NeverType>(there.tops))
     {
@@ -3162,7 +3169,8 @@ NormalizationResult Normalizer::intersectNormalWithTy(
         }
         return NormalizationResult::True;
     }
-    else if (get<GenericType>(there) || get<FreeType>(there) || get<BlockedType>(there) || get<PendingExpansionType>(there) || get<TypeFunctionInstanceType>(there))
+    else if (get<GenericType>(there) || get<FreeType>(there) || get<BlockedType>(there) || get<PendingExpansionType>(there) ||
+             get<TypeFunctionInstanceType>(there))
     {
         NormalizedType thereNorm{builtinTypes};
         NormalizedType topNorm{builtinTypes};
@@ -3465,7 +3473,14 @@ TypeId Normalizer::typeFromNormal(const NormalizedType& norm)
         return arena->addType(UnionType{std::move(result)});
 }
 
-bool isSubtype(TypeId subTy, TypeId superTy, NotNull<Scope> scope, NotNull<BuiltinTypes> builtinTypes, InternalErrorReporter& ice)
+bool isSubtype(
+    TypeId subTy,
+    TypeId superTy,
+    NotNull<Scope> scope,
+    NotNull<BuiltinTypes> builtinTypes,
+    NotNull<Simplifier> simplifier,
+    InternalErrorReporter& ice
+)
 {
     UnifierSharedState sharedState{&ice};
     TypeArena arena;
@@ -3478,7 +3493,7 @@ bool isSubtype(TypeId subTy, TypeId superTy, NotNull<Scope> scope, NotNull<Built
     // Subtyping under DCR is not implemented using unification!
     if (FFlag::LuauSolverV2)
     {
-        Subtyping subtyping{builtinTypes, NotNull{&arena}, NotNull{&normalizer}, NotNull{&typeFunctionRuntime}, NotNull{&ice}};
+        Subtyping subtyping{builtinTypes, NotNull{&arena}, simplifier, NotNull{&normalizer}, NotNull{&typeFunctionRuntime}, NotNull{&ice}};
 
         return subtyping.isSubtype(subTy, superTy, scope).isSubtype;
     }
@@ -3491,7 +3506,14 @@ bool isSubtype(TypeId subTy, TypeId superTy, NotNull<Scope> scope, NotNull<Built
     }
 }
 
-bool isSubtype(TypePackId subPack, TypePackId superPack, NotNull<Scope> scope, NotNull<BuiltinTypes> builtinTypes, InternalErrorReporter& ice)
+bool isSubtype(
+    TypePackId subPack,
+    TypePackId superPack,
+    NotNull<Scope> scope,
+    NotNull<BuiltinTypes> builtinTypes,
+    NotNull<Simplifier> simplifier,
+    InternalErrorReporter& ice
+)
 {
     UnifierSharedState sharedState{&ice};
     TypeArena arena;
@@ -3504,7 +3526,7 @@ bool isSubtype(TypePackId subPack, TypePackId superPack, NotNull<Scope> scope, N
     // Subtyping under DCR is not implemented using unification!
     if (FFlag::LuauSolverV2)
     {
-        Subtyping subtyping{builtinTypes, NotNull{&arena}, NotNull{&normalizer}, NotNull{&typeFunctionRuntime}, NotNull{&ice}};
+        Subtyping subtyping{builtinTypes, NotNull{&arena}, simplifier, NotNull{&normalizer}, NotNull{&typeFunctionRuntime}, NotNull{&ice}};
 
         return subtyping.isSubtype(subPack, superPack, scope).isSubtype;
     }

Analysis/src/OverloadResolution.cpp

@@ -16,6 +16,7 @@ namespace Luau
 OverloadResolver::OverloadResolver(
     NotNull<BuiltinTypes> builtinTypes,
     NotNull<TypeArena> arena,
+    NotNull<Simplifier> simplifier,
     NotNull<Normalizer> normalizer,
     NotNull<TypeFunctionRuntime> typeFunctionRuntime,
     NotNull<Scope> scope,
@@ -25,12 +26,13 @@ OverloadResolver::OverloadResolver(
 )
     : builtinTypes(builtinTypes)
     , arena(arena)
+    , simplifier(simplifier)
     , normalizer(normalizer)
     , typeFunctionRuntime(typeFunctionRuntime)
     , scope(scope)
     , ice(reporter)
     , limits(limits)
-    , subtyping({builtinTypes, arena, normalizer, typeFunctionRuntime, ice})
+    , subtyping({builtinTypes, arena, simplifier, normalizer, typeFunctionRuntime, ice})
     , callLoc(callLocation)
 {
 }
@@ -202,7 +204,7 @@ std::pair<OverloadResolver::Analysis, ErrorVec> OverloadResolver::checkOverload_
 )
 {
     FunctionGraphReductionResult result = reduceTypeFunctions(
-        fnTy, callLoc, TypeFunctionContext{arena, builtinTypes, scope, normalizer, typeFunctionRuntime, ice, limits}, /*force=*/true
+        fnTy, callLoc, TypeFunctionContext{arena, builtinTypes, scope, simplifier, normalizer, typeFunctionRuntime, ice, limits}, /*force=*/true
     );
     if (!result.errors.empty())
         return {OverloadIsNonviable, result.errors};
@@ -404,9 +406,10 @@ void OverloadResolver::add(Analysis analysis, TypeId ty, ErrorVec&& errors)
 
 // we wrap calling the overload resolver in a separate function to reduce overall stack pressure in `solveFunctionCall`.
 // this limits the lifetime of `OverloadResolver`, a large type, to only as long as it is actually needed.
-std::optional<TypeId> selectOverload(
+static std::optional<TypeId> selectOverload(
     NotNull<BuiltinTypes> builtinTypes,
     NotNull<TypeArena> arena,
+    NotNull<Simplifier> simplifier,
     NotNull<Normalizer> normalizer,
     NotNull<TypeFunctionRuntime> typeFunctionRuntime,
     NotNull<Scope> scope,
@@ -417,7 +420,8 @@ std::optional<TypeId> selectOverload(
     TypePackId argsPack
 )
 {
-    auto resolver = std::make_unique<OverloadResolver>(builtinTypes, arena, normalizer, typeFunctionRuntime, scope, iceReporter, limits, location);
+    auto resolver =
+        std::make_unique<OverloadResolver>(builtinTypes, arena, simplifier, normalizer, typeFunctionRuntime, scope, iceReporter, limits, location);
     auto [status, overload] = resolver->selectOverload(fn, argsPack);
 
     if (status == OverloadResolver::Analysis::Ok)
@@ -432,6 +436,7 @@ std::optional<TypeId> selectOverload(
 SolveResult solveFunctionCall(
     NotNull<TypeArena> arena,
     NotNull<BuiltinTypes> builtinTypes,
+    NotNull<Simplifier> simplifier,
     NotNull<Normalizer> normalizer,
     NotNull<TypeFunctionRuntime> typeFunctionRuntime,
     NotNull<InternalErrorReporter> iceReporter,
@@ -443,7 +448,7 @@ SolveResult solveFunctionCall(
 )
 {
     std::optional<TypeId> overloadToUse =
-        selectOverload(builtinTypes, arena, normalizer, typeFunctionRuntime, scope, iceReporter, limits, location, fn, argsPack);
+        selectOverload(builtinTypes, arena, simplifier, normalizer, typeFunctionRuntime, scope, iceReporter, limits, location, fn, argsPack);
     if (!overloadToUse)
         return {SolveResult::NoMatchingOverload};
 

Analysis/src/Scope.cpp

@@ -211,6 +211,16 @@ void Scope::inheritRefinements(const ScopePtr& childScope)
     }
 }
 
+bool Scope::shouldWarnGlobal(std::string name) const
+{
+    for (const Scope* current = this; current; current = current->parent.get())
+    {
+        if (current->globalsToWarn.contains(name))
+            return true;
+    }
+    return false;
+}
+
 bool subsumesStrict(Scope* left, Scope* right)
 {
     while (right)

Analysis/src/Simplify.cpp

@@ -31,16 +31,16 @@ struct TypeSimplifier
 
     int recursionDepth = 0;
 
-    TypeId mkNegation(TypeId ty);
+    TypeId mkNegation(TypeId ty) const;
 
     TypeId intersectFromParts(std::set<TypeId> parts);
 
-    TypeId intersectUnionWithType(TypeId unionTy, TypeId right);
+    TypeId intersectUnionWithType(TypeId left, TypeId right);
     TypeId intersectUnions(TypeId left, TypeId right);
-    TypeId intersectNegatedUnion(TypeId unionTy, TypeId right);
+    TypeId intersectNegatedUnion(TypeId left, TypeId right);
 
-    TypeId intersectTypeWithNegation(TypeId a, TypeId b);
-    TypeId intersectNegations(TypeId a, TypeId b);
+    TypeId intersectTypeWithNegation(TypeId left, TypeId right);
+    TypeId intersectNegations(TypeId left, TypeId right);
 
     TypeId intersectIntersectionWithType(TypeId left, TypeId right);
 
@@ -48,8 +48,8 @@ struct TypeSimplifier
     // unions, intersections, or negations.
     std::optional<TypeId> basicIntersect(TypeId left, TypeId right);
 
-    TypeId intersect(TypeId ty, TypeId discriminant);
-    TypeId union_(TypeId ty, TypeId discriminant);
+    TypeId intersect(TypeId left, TypeId right);
+    TypeId union_(TypeId left, TypeId right);
 
     TypeId simplify(TypeId ty);
     TypeId simplify(TypeId ty, DenseHashSet<TypeId>& seen);
@@ -573,7 +573,7 @@ Relation relate(TypeId left, TypeId right)
     return relate(left, right, seen);
 }
 
-TypeId TypeSimplifier::mkNegation(TypeId ty)
+TypeId TypeSimplifier::mkNegation(TypeId ty) const
 {
     TypeId result = nullptr;
 

Analysis/src/Substitution.cpp

@@ -98,9 +98,7 @@ static TypeId shallowClone(TypeId ty, TypeArena& dest, const TxnLog* log, bool a
             FunctionType clone = FunctionType{a.level, a.scope, a.argTypes, a.retTypes, a.definition, a.hasSelf};
             clone.generics = a.generics;
             clone.genericPacks = a.genericPacks;
-            clone.magicFunction = a.magicFunction;
-            clone.dcrMagicFunction = a.dcrMagicFunction;
-            clone.dcrMagicRefinement = a.dcrMagicRefinement;
+            clone.magic = a.magic;
             clone.tags = a.tags;
             clone.argNames = a.argNames;
             clone.isCheckedFunction = a.isCheckedFunction;

Analysis/src/Subtyping.cpp

@@ -22,7 +22,6 @@
 #include <algorithm>
 
 LUAU_FASTFLAGVARIABLE(DebugLuauSubtypingCheckPathValidity)
-LUAU_FASTFLAGVARIABLE(LuauRetrySubtypingWithoutHiddenPack)
 
 namespace Luau
 {
@@ -396,12 +395,14 @@ TypePackId* SubtypingEnvironment::getMappedPackBounds(TypePackId tp)
 Subtyping::Subtyping(
     NotNull<BuiltinTypes> builtinTypes,
     NotNull<TypeArena> typeArena,
+    NotNull<Simplifier> simplifier,
     NotNull<Normalizer> normalizer,
     NotNull<TypeFunctionRuntime> typeFunctionRuntime,
     NotNull<InternalErrorReporter> iceReporter
 )
     : builtinTypes(builtinTypes)
     , arena(typeArena)
+    , simplifier(simplifier)
     , normalizer(normalizer)
     , typeFunctionRuntime(typeFunctionRuntime)
     , iceReporter(iceReporter)
@@ -1472,15 +1473,14 @@ SubtypingResult Subtyping::isCovariantWith(
 
         // If subtyping failed in the argument packs, we should check if there's a hidden variadic tail and try ignoring it.
         // This might cause subtyping correctly because the sub type here may not have a hidden variadic tail or equivalent.
-        if (FFlag::LuauRetrySubtypingWithoutHiddenPack && !result.isSubtype)
+        if (!result.isSubtype)
         {
             auto [arguments, tail] = flatten(superFunction->argTypes);
 
             if (auto variadic = get<VariadicTypePack>(tail); variadic && variadic->hidden)
             {
-                result.orElse(
-                    isContravariantWith(env, subFunction->argTypes, arena->addTypePack(TypePack{arguments}), scope).withBothComponent(TypePath::PackField::Arguments)
-                );
+                result.orElse(isContravariantWith(env, subFunction->argTypes, arena->addTypePack(TypePack{arguments}), scope)
+                                  .withBothComponent(TypePath::PackField::Arguments));
             }
         }
     }
@@ -1861,7 +1861,7 @@ TypeId Subtyping::makeAggregateType(const Container& container, TypeId orElse)
 
 std::pair<TypeId, ErrorVec> Subtyping::handleTypeFunctionReductionResult(const TypeFunctionInstanceType* functionInstance, NotNull<Scope> scope)
 {
-    TypeFunctionContext context{arena, builtinTypes, scope, normalizer, typeFunctionRuntime, iceReporter, NotNull{&limits}};
+    TypeFunctionContext context{arena, builtinTypes, scope, simplifier, normalizer, typeFunctionRuntime, iceReporter, NotNull{&limits}};
     TypeId function = arena->addType(*functionInstance);
     FunctionGraphReductionResult result = reduceTypeFunctions(function, {}, context, true);
     ErrorVec errors;

Analysis/src/TableLiteralInference.cpp

@@ -9,6 +9,8 @@
 #include "Luau/TypeUtils.h"
 #include "Luau/Unifier2.h"
 
+LUAU_FASTFLAGVARIABLE(LuauDontInPlaceMutateTableType)
+
 namespace Luau
 {
 
@@ -236,6 +238,8 @@ TypeId matchLiteralType(
             return exprType;
         }
 
+        DenseHashSet<AstExprConstantString*> keysToDelete{nullptr};
+
         for (const AstExprTable::Item& item : exprTable->items)
         {
             if (isRecord(item))
@@ -280,7 +284,10 @@ TypeId matchLiteralType(
                         else
                             tableTy->indexer = TableIndexer{expectedTableTy->indexer->indexType, matchedType};
 
-                        tableTy->props.erase(keyStr);
+                        if (FFlag::LuauDontInPlaceMutateTableType)
+                            keysToDelete.insert(item.key->as<AstExprConstantString>());
+                        else
+                            tableTy->props.erase(keyStr);
                     }
 
                     // If it's just an extra property and the expected type
@@ -387,6 +394,16 @@ TypeId matchLiteralType(
                 LUAU_ASSERT(!"Unexpected");
         }
 
+        if (FFlag::LuauDontInPlaceMutateTableType)
+        {
+            for (const auto& key: keysToDelete)
+            {
+                const AstArray<char>& s = key->value;
+                std::string keyStr{s.data, s.data + s.size};
+                tableTy->props.erase(keyStr);
+            }
+        }
+
         // Keys that the expectedType says we should have, but that aren't
         // specified by the AST fragment.
         //

Analysis/src/Type.cpp

@@ -27,6 +27,7 @@ LUAU_FASTINTVARIABLE(LuauTypeMaximumStringifierLength, 500)
 LUAU_FASTINTVARIABLE(LuauTableTypeMaximumStringifierLength, 0)
 LUAU_FASTINT(LuauTypeInferRecursionLimit)
 LUAU_FASTFLAG(LuauInstantiateInSubtyping)
+LUAU_FASTFLAGVARIABLE(LuauFreeTypesMustHaveBounds)
 
 namespace Luau
 {
@@ -478,24 +479,12 @@ bool hasLength(TypeId ty, DenseHashSet<TypeId>& seen, int* recursionCount)
     return false;
 }
 
-FreeType::FreeType(TypeLevel level)
+// New constructors
+FreeType::FreeType(TypeLevel level, TypeId lowerBound, TypeId upperBound)
     : index(Unifiable::freshIndex())
     , level(level)
-    , scope(nullptr)
-{
-}
-
-FreeType::FreeType(Scope* scope)
-    : index(Unifiable::freshIndex())
-    , level{}
-    , scope(scope)
-{
-}
-
-FreeType::FreeType(Scope* scope, TypeLevel level)
-    : index(Unifiable::freshIndex())
-    , level(level)
-    , scope(scope)
+    , lowerBound(lowerBound)
+    , upperBound(upperBound)
 {
 }
 
@@ -507,6 +496,40 @@ FreeType::FreeType(Scope* scope, TypeId lowerBound, TypeId upperBound)
 {
 }
 
+FreeType::FreeType(Scope* scope, TypeLevel level, TypeId lowerBound, TypeId upperBound)
+    : index(Unifiable::freshIndex())
+    , level(level)
+    , scope(scope)
+    , lowerBound(lowerBound)
+    , upperBound(upperBound)
+{
+}
+
+// Old constructors
+FreeType::FreeType(TypeLevel level)
+    : index(Unifiable::freshIndex())
+    , level(level)
+    , scope(nullptr)
+{
+    LUAU_ASSERT(!FFlag::LuauFreeTypesMustHaveBounds);
+}
+
+FreeType::FreeType(Scope* scope)
+    : index(Unifiable::freshIndex())
+    , level{}
+    , scope(scope)
+{
+    LUAU_ASSERT(!FFlag::LuauFreeTypesMustHaveBounds);
+}
+
+FreeType::FreeType(Scope* scope, TypeLevel level)
+    : index(Unifiable::freshIndex())
+    , level(level)
+    , scope(scope)
+{
+    LUAU_ASSERT(!FFlag::LuauFreeTypesMustHaveBounds);
+}
+
 GenericType::GenericType()
     : index(Unifiable::freshIndex())
     , name("g" + std::to_string(index))
@@ -554,12 +577,12 @@ BlockedType::BlockedType()
 {
 }
 
-Constraint* BlockedType::getOwner() const
+const Constraint* BlockedType::getOwner() const
 {
     return owner;
 }
 
-void BlockedType::setOwner(Constraint* newOwner)
+void BlockedType::setOwner(const Constraint* newOwner)
 {
     LUAU_ASSERT(owner == nullptr);
 
@@ -569,7 +592,7 @@ void BlockedType::setOwner(Constraint* newOwner)
     owner = newOwner;
 }
 
-void BlockedType::replaceOwner(Constraint* newOwner)
+void BlockedType::replaceOwner(const Constraint* newOwner)
 {
     owner = newOwner;
 }

Analysis/src/TypeArena.cpp

@@ -3,6 +3,7 @@
 #include "Luau/TypeArena.h"
 
 LUAU_FASTFLAGVARIABLE(DebugLuauFreezeArena);
+LUAU_FASTFLAG(LuauFreeTypesMustHaveBounds)
 
 namespace Luau
 {
@@ -22,7 +23,34 @@ TypeId TypeArena::addTV(Type&& tv)
     return allocated;
 }
 
-TypeId TypeArena::freshType(TypeLevel level)
+TypeId TypeArena::freshType(NotNull<BuiltinTypes> builtins, TypeLevel level)
+{
+    TypeId allocated = types.allocate(FreeType{level, builtins->neverType, builtins->unknownType});
+
+    asMutable(allocated)->owningArena = this;
+
+    return allocated;
+}
+
+TypeId TypeArena::freshType(NotNull<BuiltinTypes> builtins, Scope* scope)
+{
+    TypeId allocated = types.allocate(FreeType{scope, builtins->neverType, builtins->unknownType});
+
+    asMutable(allocated)->owningArena = this;
+
+    return allocated;
+}
+
+TypeId TypeArena::freshType(NotNull<BuiltinTypes> builtins, Scope* scope, TypeLevel level)
+{
+    TypeId allocated = types.allocate(FreeType{scope, level, builtins->neverType, builtins->unknownType});
+
+    asMutable(allocated)->owningArena = this;
+
+    return allocated;
+}
+
+TypeId TypeArena::freshType_DEPRECATED(TypeLevel level)
 {
     TypeId allocated = types.allocate(FreeType{level});
 
@@ -31,7 +59,7 @@ TypeId TypeArena::freshType(TypeLevel level)
     return allocated;
 }
 
-TypeId TypeArena::freshType(Scope* scope)
+TypeId TypeArena::freshType_DEPRECATED(Scope* scope)
 {
     TypeId allocated = types.allocate(FreeType{scope});
 
@@ -40,7 +68,7 @@ TypeId TypeArena::freshType(Scope* scope)
     return allocated;
 }
 
-TypeId TypeArena::freshType(Scope* scope, TypeLevel level)
+TypeId TypeArena::freshType_DEPRECATED(Scope* scope, TypeLevel level)
 {
     TypeId allocated = types.allocate(FreeType{scope, level});
 

Analysis/src/TypeAttach.cpp

@@ -386,8 +386,12 @@ public:
     }
     AstType* operator()(const NegationType& ntv)
     {
-        // FIXME: do the same thing we do with ErrorType
-        throw InternalCompilerError("Cannot convert NegationType into AstNode");
+        AstArray<AstTypeOrPack> params;
+        params.size = 1;
+        params.data = static_cast<AstTypeOrPack*>(allocator->allocate(sizeof(AstType*)));
+        params.data[0] = AstTypeOrPack{Luau::visit(*this, ntv.ty->ty), nullptr};
+
+        return allocator->alloc<AstTypeReference>(Location(), std::nullopt, AstName("negate"), std::nullopt, Location(), true, params);
     }
     AstType* operator()(const TypeFunctionInstanceType& tfit)
     {

Analysis/src/TypeChecker2.cpp

@@ -7,7 +7,6 @@
 #include "Luau/DcrLogger.h"
 #include "Luau/DenseHash.h"
 #include "Luau/Error.h"
-#include "Luau/InsertionOrderedMap.h"
 #include "Luau/Instantiation.h"
 #include "Luau/Metamethods.h"
 #include "Luau/Normalize.h"
@@ -27,12 +26,12 @@
 #include "Luau/VisitType.h"
 
 #include <algorithm>
-#include <iostream>
-#include <ostream>
 
 LUAU_FASTFLAG(DebugLuauMagicTypes)
 
+LUAU_FASTFLAG(InferGlobalTypes)
 LUAU_FASTFLAGVARIABLE(LuauTableKeysAreRValues)
+LUAU_FASTFLAG(LuauFreeTypesMustHaveBounds)
 
 namespace Luau
 {
@@ -175,7 +174,7 @@ struct InternalTypeFunctionFinder : TypeOnceVisitor
     DenseHashSet<TypeId> mentionedFunctions{nullptr};
     DenseHashSet<TypePackId> mentionedFunctionPacks{nullptr};
 
-    InternalTypeFunctionFinder(std::vector<TypeId>& declStack)
+    explicit InternalTypeFunctionFinder(std::vector<TypeId>& declStack)
     {
         TypeFunctionFinder f;
         for (TypeId fn : declStack)
@@ -268,6 +267,7 @@ struct InternalTypeFunctionFinder : TypeOnceVisitor
 
 void check(
     NotNull<BuiltinTypes> builtinTypes,
+    NotNull<Simplifier> simplifier,
     NotNull<TypeFunctionRuntime> typeFunctionRuntime,
     NotNull<UnifierSharedState> unifierState,
     NotNull<TypeCheckLimits> limits,
@@ -278,7 +278,7 @@ void check(
 {
     LUAU_TIMETRACE_SCOPE("check", "Typechecking");
 
-    TypeChecker2 typeChecker{builtinTypes, typeFunctionRuntime, unifierState, limits, logger, &sourceModule, module};
+    TypeChecker2 typeChecker{builtinTypes, simplifier, typeFunctionRuntime, unifierState, limits, logger, &sourceModule, module};
 
     typeChecker.visit(sourceModule.root);
 
@@ -295,6 +295,7 @@ void check(
 
 TypeChecker2::TypeChecker2(
     NotNull<BuiltinTypes> builtinTypes,
+    NotNull<Simplifier> simplifier,
     NotNull<TypeFunctionRuntime> typeFunctionRuntime,
     NotNull<UnifierSharedState> unifierState,
     NotNull<TypeCheckLimits> limits,
@@ -303,6 +304,7 @@ TypeChecker2::TypeChecker2(
     Module* module
 )
     : builtinTypes(builtinTypes)
+    , simplifier(simplifier)
     , typeFunctionRuntime(typeFunctionRuntime)
     , logger(logger)
     , limits(limits)
@@ -310,7 +312,7 @@ TypeChecker2::TypeChecker2(
     , sourceModule(sourceModule)
     , module(module)
     , normalizer{&module->internalTypes, builtinTypes, unifierState, /* cacheInhabitance */ true}
-    , _subtyping{builtinTypes, NotNull{&module->internalTypes}, NotNull{&normalizer}, typeFunctionRuntime, NotNull{unifierState->iceHandler}}
+    , _subtyping{builtinTypes, NotNull{&module->internalTypes}, simplifier, NotNull{&normalizer}, typeFunctionRuntime, NotNull{unifierState->iceHandler}}
     , subtyping(&_subtyping)
 {
 }
@@ -492,7 +494,9 @@ TypeId TypeChecker2::checkForTypeFunctionInhabitance(TypeId instance, Location l
         reduceTypeFunctions(
             instance,
             location,
-            TypeFunctionContext{NotNull{&module->internalTypes}, builtinTypes, stack.back(), NotNull{&normalizer}, typeFunctionRuntime, ice, limits},
+            TypeFunctionContext{
+                NotNull{&module->internalTypes}, builtinTypes, stack.back(), simplifier, NotNull{&normalizer}, typeFunctionRuntime, ice, limits
+            },
             true
         )
             .errors;
@@ -501,7 +505,7 @@ TypeId TypeChecker2::checkForTypeFunctionInhabitance(TypeId instance, Location l
     return instance;
 }
 
-TypePackId TypeChecker2::lookupPack(AstExpr* expr)
+TypePackId TypeChecker2::lookupPack(AstExpr* expr) const
 {
     // If a type isn't in the type graph, it probably means that a recursion limit was exceeded.
     // We'll just return anyType in these cases.  Typechecking against any is very fast and this
@@ -551,7 +555,7 @@ TypeId TypeChecker2::lookupAnnotation(AstType* annotation)
     return checkForTypeFunctionInhabitance(follow(*ty), annotation->location);
 }
 
-std::optional<TypePackId> TypeChecker2::lookupPackAnnotation(AstTypePack* annotation)
+std::optional<TypePackId> TypeChecker2::lookupPackAnnotation(AstTypePack* annotation) const
 {
     TypePackId* tp = module->astResolvedTypePacks.find(annotation);
     if (tp != nullptr)
@@ -559,7 +563,7 @@ std::optional<TypePackId> TypeChecker2::lookupPackAnnotation(AstTypePack* annota
     return {};
 }
 
-TypeId TypeChecker2::lookupExpectedType(AstExpr* expr)
+TypeId TypeChecker2::lookupExpectedType(AstExpr* expr) const
 {
     if (TypeId* ty = module->astExpectedTypes.find(expr))
         return follow(*ty);
@@ -567,7 +571,7 @@ TypeId TypeChecker2::lookupExpectedType(AstExpr* expr)
     return builtinTypes->anyType;
 }
 
-TypePackId TypeChecker2::lookupExpectedPack(AstExpr* expr, TypeArena& arena)
+TypePackId TypeChecker2::lookupExpectedPack(AstExpr* expr, TypeArena& arena) const
 {
     if (TypeId* ty = module->astExpectedTypes.find(expr))
         return arena.addTypePack(TypePack{{follow(*ty)}, std::nullopt});
@@ -591,7 +595,7 @@ TypePackId TypeChecker2::reconstructPack(AstArray<AstExpr*> exprs, TypeArena& ar
     return arena.addTypePack(TypePack{head, tail});
 }
 
-Scope* TypeChecker2::findInnermostScope(Location location)
+Scope* TypeChecker2::findInnermostScope(Location location) const
 {
     Scope* bestScope = module->getModuleScope().get();
 
@@ -1014,7 +1018,8 @@ void TypeChecker2::visit(AstStatForIn* forInStatement)
     {
         reportError(OptionalValueAccess{iteratorTy}, forInStatement->values.data[0]->location);
     }
-    else if (std::optional<TypeId> iterMmTy = findMetatableEntry(builtinTypes, module->errors, iteratorTy, "__iter", forInStatement->values.data[0]->location))
+    else if (std::optional<TypeId> iterMmTy =
+                 findMetatableEntry(builtinTypes, module->errors, iteratorTy, "__iter", forInStatement->values.data[0]->location))
     {
         Instantiation instantiation{TxnLog::empty(), &arena, builtinTypes, TypeLevel{}, scope};
 
@@ -1349,7 +1354,17 @@ void TypeChecker2::visit(AstExprGlobal* expr)
 {
     NotNull<Scope> scope = stack.back();
     if (!scope->lookup(expr->name))
+    {
         reportError(UnknownSymbol{expr->name.value, UnknownSymbol::Binding}, expr->location);
+    }
+    else if (FFlag::InferGlobalTypes)
+    {
+        if (scope->shouldWarnGlobal(expr->name.value) && !warnedGlobals.contains(expr->name.value))
+        {
+            reportError(UnknownSymbol{expr->name.value, UnknownSymbol::Binding}, expr->location);
+            warnedGlobals.insert(expr->name.value);
+        }
+    }
 }
 
 void TypeChecker2::visit(AstExprVarargs* expr)
@@ -1437,10 +1452,11 @@ void TypeChecker2::visitCall(AstExprCall* call)
     TypePackId argsTp = module->internalTypes.addTypePack(args);
     if (auto ftv = get<FunctionType>(follow(*originalCallTy)))
     {
-        if (ftv->dcrMagicTypeCheck)
+        if (ftv->magic)
         {
-            ftv->dcrMagicTypeCheck(MagicFunctionTypeCheckContext{NotNull{this}, builtinTypes, call, argsTp, scope});
-            return;
+            bool usedMagic = ftv->magic->typeCheck(MagicFunctionTypeCheckContext{NotNull{this}, builtinTypes, call, argsTp, scope});
+            if (usedMagic)
+                return;
         }
     }
 
@@ -1448,6 +1464,7 @@ void TypeChecker2::visitCall(AstExprCall* call)
     OverloadResolver resolver{
         builtinTypes,
         NotNull{&module->internalTypes},
+        simplifier,
         NotNull{&normalizer},
         typeFunctionRuntime,
         NotNull{stack.back()},
@@ -1545,7 +1562,7 @@ void TypeChecker2::visit(AstExprCall* call)
     visitCall(call);
 }
 
-std::optional<TypeId> TypeChecker2::tryStripUnionFromNil(TypeId ty)
+std::optional<TypeId> TypeChecker2::tryStripUnionFromNil(TypeId ty) const
 {
     if (const UnionType* utv = get<UnionType>(ty))
     {
@@ -2089,7 +2106,10 @@ TypeId TypeChecker2::visit(AstExprBinary* expr, AstNode* overrideKey)
                 }
                 else
                 {
-                    expectedRets = module->internalTypes.addTypePack({module->internalTypes.freshType(scope, TypeLevel{})});
+                    expectedRets = module->internalTypes.addTypePack(
+                        {FFlag::LuauFreeTypesMustHaveBounds ? module->internalTypes.freshType(builtinTypes, scope, TypeLevel{})
+                                                            : module->internalTypes.freshType_DEPRECATED(scope, TypeLevel{})}
+                    );
                 }
 
                 TypeId expectedTy = module->internalTypes.addType(FunctionType(expectedArgs, expectedRets));
@@ -2341,7 +2361,8 @@ TypeId TypeChecker2::flattenPack(TypePackId pack)
         return *fst;
     else if (auto ftp = get<FreeTypePack>(pack))
     {
-        TypeId result = module->internalTypes.addType(FreeType{ftp->scope});
+        TypeId result = FFlag::LuauFreeTypesMustHaveBounds ? module->internalTypes.freshType(builtinTypes, ftp->scope)
+                                                           : module->internalTypes.addType(FreeType{ftp->scope});
         TypePackId freeTail = module->internalTypes.addTypePack(FreeTypePack{ftp->scope});
 
         TypePack* resultPack = emplaceTypePack<TypePack>(asMutable(pack));
@@ -2403,6 +2424,8 @@ void TypeChecker2::visit(AstType* ty)
         return visit(t);
     else if (auto t = ty->as<AstTypeIntersection>())
         return visit(t);
+    else if (auto t = ty->as<AstTypeGroup>())
+        return visit(t->type);
 }
 
 void TypeChecker2::visit(AstTypeReference* ty)
@@ -3024,7 +3047,7 @@ PropertyType TypeChecker2::hasIndexTypeFromType(
         {
             TypeId indexType = follow(tt->indexer->indexType);
             TypeId givenType = module->internalTypes.addType(SingletonType{StringSingleton{prop}});
-            if (isSubtype(givenType, indexType, NotNull{module->getModuleScope().get()}, builtinTypes, *ice))
+            if (isSubtype(givenType, indexType, NotNull{module->getModuleScope().get()}, builtinTypes, simplifier, *ice))
                 return {NormalizationResult::True, {tt->indexer->indexResultType}};
         }
 

Analysis/src/TypeFunctionRuntimeBuilder.cpp

@@ -20,8 +20,7 @@
 // currently, controls serialization, deserialization, and `type.copy`
 LUAU_DYNAMIC_FASTINTVARIABLE(LuauTypeFunctionSerdeIterationLimit, 100'000);
 
-LUAU_FASTFLAGVARIABLE(LuauUserTypeFunFixMetatable)
-LUAU_FASTFLAG(LuauUserTypeFunThreadBuffer)
+LUAU_FASTFLAG(LuauUserTypeFunGenerics)
 
 namespace Luau
 {
@@ -161,26 +160,10 @@ private:
                 target = typeFunctionRuntime->typeArena.allocate(TypeFunctionPrimitiveType(TypeFunctionPrimitiveType::String));
                 break;
             case PrimitiveType::Thread:
-                if (FFlag::LuauUserTypeFunThreadBuffer)
-                {
-                    target = typeFunctionRuntime->typeArena.allocate(TypeFunctionPrimitiveType(TypeFunctionPrimitiveType::Thread));
-                }
-                else
-                {
-                    std::string error = format("Argument of primitive type %s is not currently serializable by type functions", toString(ty).c_str());
-                    state->errors.push_back(error);
-                }
+                target = typeFunctionRuntime->typeArena.allocate(TypeFunctionPrimitiveType(TypeFunctionPrimitiveType::Thread));
                 break;
             case PrimitiveType::Buffer:
-                if (FFlag::LuauUserTypeFunThreadBuffer)
-                {
-                    target = typeFunctionRuntime->typeArena.allocate(TypeFunctionPrimitiveType(TypeFunctionPrimitiveType::Buffer));
-                }
-                else
-                {
-                    std::string error = format("Argument of primitive type %s is not currently serializable by type functions", toString(ty).c_str());
-                    state->errors.push_back(error);
-                }
+                target = typeFunctionRuntime->typeArena.allocate(TypeFunctionPrimitiveType(TypeFunctionPrimitiveType::Buffer));
                 break;
             case PrimitiveType::Function:
             case PrimitiveType::Table:
@@ -222,13 +205,22 @@ private:
         else if (auto f = get<FunctionType>(ty))
         {
             TypeFunctionTypePackId emptyTypePack = typeFunctionRuntime->typePackArena.allocate(TypeFunctionTypePack{});
-            target = typeFunctionRuntime->typeArena.allocate(TypeFunctionFunctionType{emptyTypePack, emptyTypePack});
+            target = typeFunctionRuntime->typeArena.allocate(TypeFunctionFunctionType{{}, {}, emptyTypePack, emptyTypePack});
         }
         else if (auto c = get<ClassType>(ty))
         {
             state->classesSerialized[c->name] = ty;
             target = typeFunctionRuntime->typeArena.allocate(TypeFunctionClassType{{}, std::nullopt, std::nullopt, std::nullopt, c->name});
         }
+        else if (auto g = get<GenericType>(ty); FFlag::LuauUserTypeFunGenerics && g)
+        {
+            Name name = g->name;
+
+            if (!g->explicitName)
+                name = format("g%d", g->index);
+
+            target = typeFunctionRuntime->typeArena.allocate(TypeFunctionGenericType{g->explicitName, false, name});
+        }
         else
         {
             std::string error = format("Argument of type %s is not currently serializable by type functions", toString(ty).c_str());
@@ -253,6 +245,15 @@ private:
             target = typeFunctionRuntime->typePackArena.allocate(TypeFunctionTypePack{{}});
         else if (auto vPack = get<VariadicTypePack>(tp))
             target = typeFunctionRuntime->typePackArena.allocate(TypeFunctionVariadicTypePack{});
+        else if (auto gPack = get<GenericTypePack>(tp); FFlag::LuauUserTypeFunGenerics && gPack)
+        {
+            Name name = gPack->name;
+
+            if (!gPack->explicitName)
+                name = format("g%d", gPack->index);
+
+            target = typeFunctionRuntime->typePackArena.allocate(TypeFunctionGenericTypePack{gPack->explicitName, name});
+        }
         else
         {
             std::string error = format("Argument of type pack %s is not currently serializable by type functions", toString(tp).c_str());
@@ -290,6 +291,9 @@ private:
             serializeChildren(f1, f2);
         else if (auto [c1, c2] = std::tuple{get<ClassType>(ty), getMutable<TypeFunctionClassType>(tfti)}; c1 && c2)
             serializeChildren(c1, c2);
+        else if (auto [g1, g2] = std::tuple{get<GenericType>(ty), getMutable<TypeFunctionGenericType>(tfti)};
+                 FFlag::LuauUserTypeFunGenerics && g1 && g2)
+            serializeChildren(g1, g2);
         else
         { // Either this or ty and tfti do not represent the same type
             std::string error = format("Argument of type %s is not currently serializable by type functions", toString(ty).c_str());
@@ -303,6 +307,9 @@ private:
             serializeChildren(tPack1, tPack2);
         else if (auto [vPack1, vPack2] = std::tuple{get<VariadicTypePack>(tp), getMutable<TypeFunctionVariadicTypePack>(tftp)}; vPack1 && vPack2)
             serializeChildren(vPack1, vPack2);
+        else if (auto [gPack1, gPack2] = std::tuple{get<GenericTypePack>(tp), getMutable<TypeFunctionGenericTypePack>(tftp)};
+                 FFlag::LuauUserTypeFunGenerics && gPack1 && gPack2)
+            serializeChildren(gPack1, gPack2);
         else
         { // Either this or ty and tfti do not represent the same type
             std::string error = format("Argument of type pack %s is not currently serializable by type functions", toString(tp).c_str());
@@ -383,27 +390,26 @@ private:
 
     void serializeChildren(const MetatableType* m1, TypeFunctionTableType* m2)
     {
-        if (FFlag::LuauUserTypeFunFixMetatable)
-        {
-            // Serialize main part of the metatable immediately
-            if (auto tableTy = get<TableType>(m1->table))
-                serializeChildren(tableTy, m2);
-        }
-        else
-        {
-            auto tmpTable = get<TypeFunctionTableType>(shallowSerialize(m1->table));
-            if (!tmpTable)
-                state->ctx->ice->ice("Serializing user defined type function arguments: metatable's table is not a TableType");
-
-            m2->props = tmpTable->props;
-            m2->indexer = tmpTable->indexer;
-        }
+        // Serialize main part of the metatable immediately
+        if (auto tableTy = get<TableType>(m1->table))
+            serializeChildren(tableTy, m2);
 
         m2->metatable = shallowSerialize(m1->metatable);
     }
 
     void serializeChildren(const FunctionType* f1, TypeFunctionFunctionType* f2)
     {
+        if (FFlag::LuauUserTypeFunGenerics)
+        {
+            f2->generics.reserve(f1->generics.size());
+            for (auto ty : f1->generics)
+                f2->generics.push_back(shallowSerialize(ty));
+
+            f2->genericPacks.reserve(f1->genericPacks.size());
+            for (auto tp : f1->genericPacks)
+                f2->genericPacks.push_back(shallowSerialize(tp));
+        }
+
         f2->argTypes = shallowSerialize(f1->argTypes);
         f2->retTypes = shallowSerialize(f1->retTypes);
     }
@@ -433,6 +439,11 @@ private:
             c2->parent = shallowSerialize(*c1->parent);
     }
 
+    void serializeChildren(const GenericType* g1, TypeFunctionGenericType* g2)
+    {
+        // noop.
+    }
+
     void serializeChildren(const TypePack* t1, TypeFunctionTypePack* t2)
     {
         for (const TypeId& ty : t1->head)
@@ -446,6 +457,25 @@ private:
     {
         v2->type = shallowSerialize(v1->ty);
     }
+
+    void serializeChildren(const GenericTypePack* v1, TypeFunctionGenericTypePack* v2)
+    {
+        // noop.
+    }
+};
+
+template<typename T>
+struct SerializedGeneric
+{
+    bool isNamed = false;
+    std::string name;
+    T type = nullptr;
+};
+
+struct SerializedFunctionScope
+{
+    size_t oldQueueSize = 0;
+    TypeFunctionFunctionType* function = nullptr;
 };
 
 // Complete inverse of TypeFunctionSerializer
@@ -466,6 +496,15 @@ class TypeFunctionDeserializer
     // second must be PrimitiveType; else there should be an error
     std::vector<std::tuple<TypeFunctionKind, Kind>> queue;
 
+    // Generic types and packs currently in scope
+    // Generics are resolved by name even if runtime generic type pointers are different
+    // Multiple names mapping to the same generic can be in scope for nested generic functions
+    std::vector<SerializedGeneric<TypeId>> genericTypes;
+    std::vector<SerializedGeneric<TypePackId>> genericPacks;
+
+    // To track when generics go out of scope, we have a list of queue positions at which a specific function has introduced generics
+    std::vector<SerializedFunctionScope> functionScopes;
+
     SeenTypes types;     // Mapping of TypeFunctionTypeIds that have been shallow deserialized to TypeIds
     SeenTypePacks packs; // Mapping of TypeFunctionTypePackIds that have been shallow deserialized to TypePackIds
 
@@ -477,7 +516,9 @@ public:
         , typeFunctionRuntime(state->ctx->typeFunctionRuntime)
         , queue({})
         , types({})
-        , packs({}){};
+        , packs({})
+    {
+    }
 
     TypeId deserialize(TypeFunctionTypeId ty)
     {
@@ -531,6 +572,16 @@ private:
             queue.pop_back();
 
             deserializeChildren(tfti, ty);
+
+            if (FFlag::LuauUserTypeFunGenerics)
+            {
+                // If we have completed working on all children of a function, remove the generic parameters from scope
+                if (!functionScopes.empty() && queue.size() == functionScopes.back().oldQueueSize && state->errors.empty())
+                {
+                    closeFunctionScope(functionScopes.back().function);
+                    functionScopes.pop_back();
+                }
+            }
         }
     }
 
@@ -563,6 +614,21 @@ private:
         }
     }
 
+    void closeFunctionScope(TypeFunctionFunctionType* f)
+    {
+        if (!f->generics.empty())
+        {
+            LUAU_ASSERT(genericTypes.size() >= f->generics.size());
+            genericTypes.erase(genericTypes.begin() + int(genericTypes.size() - f->generics.size()), genericTypes.end());
+        }
+
+        if (!f->genericPacks.empty())
+        {
+            LUAU_ASSERT(genericPacks.size() >= f->genericPacks.size());
+            genericPacks.erase(genericPacks.begin() + int(genericPacks.size() - f->genericPacks.size()), genericPacks.end());
+        }
+    }
+
     TypeId shallowDeserialize(TypeFunctionTypeId ty)
     {
         if (auto it = find(ty))
@@ -587,16 +653,10 @@ private:
                 target = state->ctx->builtins->stringType;
                 break;
             case TypeFunctionPrimitiveType::Type::Thread:
-                if (FFlag::LuauUserTypeFunThreadBuffer)
-                    target = state->ctx->builtins->threadType;
-                else
-                    state->ctx->ice->ice("Deserializing user defined type function arguments: mysterious type is being deserialized");
+                target = state->ctx->builtins->threadType;
                 break;
             case TypeFunctionPrimitiveType::Type::Buffer:
-                if (FFlag::LuauUserTypeFunThreadBuffer)
-                    target = state->ctx->builtins->bufferType;
-                else
-                    state->ctx->ice->ice("Deserializing user defined type function arguments: mysterious type is being deserialized");
+                target = state->ctx->builtins->bufferType;
                 break;
             default:
                 state->ctx->ice->ice("Deserializing user defined type function arguments: mysterious type is being deserialized");
@@ -642,6 +702,33 @@ private:
             else
                 state->ctx->ice->ice("Deserializing user defined type function arguments: mysterious class type is being deserialized");
         }
+        else if (auto g = get<TypeFunctionGenericType>(ty); FFlag::LuauUserTypeFunGenerics && g)
+        {
+            if (g->isPack)
+            {
+                state->errors.push_back(format("Generic type pack '%s...' cannot be placed in a type position", g->name.c_str()));
+                return nullptr;
+            }
+            else
+            {
+                auto it = std::find_if(
+                    genericTypes.rbegin(),
+                    genericTypes.rend(),
+                    [&](const SerializedGeneric<TypeId>& el)
+                    {
+                        return g->isNamed == el.isNamed && g->name == el.name;
+                    }
+                );
+
+                if (it == genericTypes.rend())
+                {
+                    state->errors.push_back(format("Generic type '%s' is not in a scope of the active generic function", g->name.c_str()));
+                    return nullptr;
+                }
+
+                target = it->type;
+            }
+        }
         else
             state->ctx->ice->ice("Deserializing user defined type function arguments: mysterious type is being deserialized");
 
@@ -658,11 +745,36 @@ private:
         // Create a shallow deserialization
         TypePackId target = {};
         if (auto tPack = get<TypeFunctionTypePack>(tp))
+        {
             target = state->ctx->arena->addTypePack(TypePack{});
+        }
         else if (auto vPack = get<TypeFunctionVariadicTypePack>(tp))
+        {
             target = state->ctx->arena->addTypePack(VariadicTypePack{});
+        }
+        else if (auto gPack = get<TypeFunctionGenericTypePack>(tp); FFlag::LuauUserTypeFunGenerics && gPack)
+        {
+            auto it = std::find_if(
+                genericPacks.rbegin(),
+                genericPacks.rend(),
+                [&](const SerializedGeneric<TypePackId>& el)
+                {
+                    return gPack->isNamed == el.isNamed && gPack->name == el.name;
+                }
+            );
+
+            if (it == genericPacks.rend())
+            {
+                state->errors.push_back(format("Generic type pack '%s...' is not in a scope of the active generic function", gPack->name.c_str()));
+                return nullptr;
+            }
+
+            target = it->type;
+        }
         else
+        {
             state->ctx->ice->ice("Deserializing user defined type function arguments: mysterious type is being deserialized");
+        }
 
         packs[tp] = target;
         queue.emplace_back(tp, target);
@@ -697,6 +809,9 @@ private:
             deserializeChildren(f2, f1);
         else if (auto [c1, c2] = std::tuple{getMutable<ClassType>(ty), getMutable<TypeFunctionClassType>(tfti)}; c1 && c2)
             deserializeChildren(c2, c1);
+        else if (auto [g1, g2] = std::tuple{getMutable<GenericType>(ty), getMutable<TypeFunctionGenericType>(tfti)};
+                 FFlag::LuauUserTypeFunGenerics && g1 && g2)
+            deserializeChildren(g2, g1);
         else
             state->ctx->ice->ice("Deserializing user defined type function arguments: mysterious type is being deserialized");
     }
@@ -708,6 +823,9 @@ private:
         else if (auto [vPack1, vPack2] = std::tuple{getMutable<VariadicTypePack>(tp), getMutable<TypeFunctionVariadicTypePack>(tftp)};
                  vPack1 && vPack2)
             deserializeChildren(vPack2, vPack1);
+        else if (auto [gPack1, gPack2] = std::tuple{getMutable<GenericTypePack>(tp), getMutable<TypeFunctionGenericTypePack>(tftp)};
+                 FFlag::LuauUserTypeFunGenerics && gPack1 && gPack2)
+            deserializeChildren(gPack2, gPack1);
         else
             state->ctx->ice->ice("Deserializing user defined type function arguments: mysterious type is being deserialized");
     }
@@ -791,6 +909,64 @@ private:
 
     void deserializeChildren(TypeFunctionFunctionType* f2, FunctionType* f1)
     {
+        if (FFlag::LuauUserTypeFunGenerics)
+        {
+            functionScopes.push_back({queue.size(), f2});
+
+            std::set<std::pair<bool, std::string>> genericNames;
+
+            // Introduce generic function parameters into scope
+            for (auto ty : f2->generics)
+            {
+                auto gty = get<TypeFunctionGenericType>(ty);
+                LUAU_ASSERT(gty && !gty->isPack);
+
+                std::pair<bool, std::string> nameKey = std::make_pair(gty->isNamed, gty->name);
+
+                // Duplicates are not allowed
+                if (genericNames.find(nameKey) != genericNames.end())
+                {
+                    state->errors.push_back(format("Duplicate type parameter '%s'", gty->name.c_str()));
+                    return;
+                }
+
+                genericNames.insert(nameKey);
+
+                TypeId mapping = state->ctx->arena->addTV(Type(gty->isNamed ? GenericType{state->ctx->scope.get(), gty->name} : GenericType{}));
+                genericTypes.push_back({gty->isNamed, gty->name, mapping});
+            }
+
+            for (auto tp : f2->genericPacks)
+            {
+                auto gtp = get<TypeFunctionGenericTypePack>(tp);
+                LUAU_ASSERT(gtp);
+
+                std::pair<bool, std::string> nameKey = std::make_pair(gtp->isNamed, gtp->name);
+
+                // Duplicates are not allowed
+                if (genericNames.find(nameKey) != genericNames.end())
+                {
+                    state->errors.push_back(format("Duplicate type parameter '%s'", gtp->name.c_str()));
+                    return;
+                }
+
+                genericNames.insert(nameKey);
+
+                TypePackId mapping =
+                    state->ctx->arena->addTypePack(TypePackVar(gtp->isNamed ? GenericTypePack{state->ctx->scope.get(), gtp->name} : GenericTypePack{})
+                    );
+                genericPacks.push_back({gtp->isNamed, gtp->name, mapping});
+            }
+
+            f1->generics.reserve(f2->generics.size());
+            for (auto ty : f2->generics)
+                f1->generics.push_back(shallowDeserialize(ty));
+
+            f1->genericPacks.reserve(f2->genericPacks.size());
+            for (auto tp : f2->genericPacks)
+                f1->genericPacks.push_back(shallowDeserialize(tp));
+        }
+
         if (f2->argTypes)
             f1->argTypes = shallowDeserialize(f2->argTypes);
 
@@ -803,6 +979,11 @@ private:
         // noop.
     }
 
+    void deserializeChildren(TypeFunctionGenericType* g2, GenericType* g1)
+    {
+        // noop.
+    }
+
     void deserializeChildren(TypeFunctionTypePack* t2, TypePack* t1)
     {
         for (TypeFunctionTypeId& ty : t2->head)
@@ -816,6 +997,11 @@ private:
     {
         v1->ty = shallowDeserialize(v2->type);
     }
+
+    void deserializeChildren(TypeFunctionGenericTypePack* v2, GenericTypePack* v1)
+    {
+        // noop.
+    }
 };
 
 TypeFunctionTypeId serialize(TypeId ty, TypeFunctionRuntimeBuilderState* state)

Analysis/src/TypeInfer.cpp

@@ -32,7 +32,9 @@ LUAU_FASTINTVARIABLE(LuauVisitRecursionLimit, 500)
 LUAU_FASTFLAG(LuauKnowsTheDataModel3)
 LUAU_FASTFLAGVARIABLE(DebugLuauFreezeDuringUnification)
 LUAU_FASTFLAG(LuauInstantiateInSubtyping)
-LUAU_FASTFLAGVARIABLE(LuauMetatableFollow)
+LUAU_FASTFLAGVARIABLE(LuauOldSolverCreatesChildScopePointers)
+LUAU_FASTFLAG(LuauPreserveUnionIntersectionNodeForLeadingTokenSingleType)
+LUAU_FASTFLAG(LuauFreeTypesMustHaveBounds)
 
 namespace Luau
 {
@@ -761,8 +763,12 @@ ControlFlow TypeChecker::check(const ScopePtr& scope, const AstStatRepeat& state
 
 struct Demoter : Substitution
 {
-    Demoter(TypeArena* arena)
+    TypeArena* arena = nullptr;
+    NotNull<BuiltinTypes> builtins;
+    Demoter(TypeArena* arena, NotNull<BuiltinTypes> builtins)
         : Substitution(TxnLog::empty(), arena)
+        , arena(arena)
+        , builtins(builtins)
     {
     }
 
@@ -788,7 +794,8 @@ struct Demoter : Substitution
     {
         auto ftv = get<FreeType>(ty);
         LUAU_ASSERT(ftv);
-        return addType(FreeType{demotedLevel(ftv->level)});
+        return FFlag::LuauFreeTypesMustHaveBounds ? arena->freshType(builtins, demotedLevel(ftv->level))
+                                                  : addType(FreeType{demotedLevel(ftv->level)});
     }
 
     TypePackId clean(TypePackId tp) override
@@ -835,7 +842,7 @@ ControlFlow TypeChecker::check(const ScopePtr& scope, const AstStatReturn& retur
         }
     }
 
-    Demoter demoter{&currentModule->internalTypes};
+    Demoter demoter{&currentModule->internalTypes, builtinTypes};
     demoter.demote(expectedTypes);
 
     TypePackId retPack = checkExprList(scope, return_.location, return_.list, false, {}, expectedTypes).type;
@@ -2799,10 +2806,10 @@ TypeId TypeChecker::checkRelationalOperation(
                 reportError(
                     expr.location,
                     GenericError{
-                    format("Type '%s' cannot be compared with relational operator %s", toString(leftType).c_str(), toString(expr.op).c_str())
-                }
-                    );
-                }
+                        format("Type '%s' cannot be compared with relational operator %s", toString(leftType).c_str(), toString(expr.op).c_str())
+                    }
+                );
+            }
 
             return booleanType;
         }
@@ -2866,7 +2873,7 @@ TypeId TypeChecker::checkRelationalOperation(
             std::optional<TypeId> metamethod = findMetatableEntry(lhsType, metamethodName, expr.location, /* addErrors= */ true);
             if (metamethod)
             {
-                if (const FunctionType* ftv = get<FunctionType>(FFlag::LuauMetatableFollow ? follow(*metamethod) : *metamethod))
+                if (const FunctionType* ftv = get<FunctionType>(follow(*metamethod)))
                 {
                     if (isEquality)
                     {
@@ -4408,7 +4415,7 @@ std::vector<std::optional<TypeId>> TypeChecker::getExpectedTypesForCall(const st
         }
     }
 
-    Demoter demoter{&currentModule->internalTypes};
+    Demoter demoter{&currentModule->internalTypes, builtinTypes};
     demoter.demote(expectedTypes);
 
     return expectedTypes;
@@ -4506,10 +4513,10 @@ std::unique_ptr<WithPredicate<TypePackId>> TypeChecker::checkCallOverload(
 
     // When this function type has magic functions and did return something, we select that overload instead.
     // TODO: pass in a Unifier object to the magic functions? This will allow the magic functions to cooperate with overload resolution.
-    if (ftv->magicFunction)
+    if (ftv->magic)
     {
         // TODO: We're passing in the wrong TypePackId. Should be argPack, but a unit test fails otherwise. CLI-40458
-        if (std::optional<WithPredicate<TypePackId>> ret = ftv->magicFunction(*this, scope, expr, argListResult))
+        if (std::optional<WithPredicate<TypePackId>> ret = ftv->magic->handleOldSolver(*this, scope, expr, argListResult))
             return std::make_unique<WithPredicate<TypePackId>>(std::move(*ret));
     }
 
@@ -5205,6 +5212,13 @@ LUAU_NOINLINE void TypeChecker::reportErrorCodeTooComplex(const Location& locati
 ScopePtr TypeChecker::childFunctionScope(const ScopePtr& parent, const Location& location, int subLevel)
 {
     ScopePtr scope = std::make_shared<Scope>(parent, subLevel);
+    if (FFlag::LuauOldSolverCreatesChildScopePointers)
+    {
+        scope->location = location;
+        scope->returnType = parent->returnType;
+        parent->children.emplace_back(scope.get());
+    }
+
     currentModule->scopes.push_back(std::make_pair(location, scope));
     return scope;
 }
@@ -5215,6 +5229,12 @@ ScopePtr TypeChecker::childScope(const ScopePtr& parent, const Location& locatio
     ScopePtr scope = std::make_shared<Scope>(parent);
     scope->level = parent->level;
     scope->varargPack = parent->varargPack;
+    if (FFlag::LuauOldSolverCreatesChildScopePointers)
+    {
+        scope->location = location;
+        scope->returnType = parent->returnType;
+        parent->children.emplace_back(scope.get());
+    }
 
     currentModule->scopes.push_back(std::make_pair(location, scope));
     return scope;
@@ -5260,7 +5280,8 @@ TypeId TypeChecker::freshType(const ScopePtr& scope)
 
 TypeId TypeChecker::freshType(TypeLevel level)
 {
-    return currentModule->internalTypes.addType(Type(FreeType(level)));
+    return FFlag::LuauFreeTypesMustHaveBounds ? currentModule->internalTypes.freshType(builtinTypes, level)
+                                              : currentModule->internalTypes.addType(Type(FreeType(level)));
 }
 
 TypeId TypeChecker::singletonType(bool value)
@@ -5705,6 +5726,12 @@ TypeId TypeChecker::resolveTypeWorker(const ScopePtr& scope, const AstType& anno
     }
     else if (const auto& un = annotation.as<AstTypeUnion>())
     {
+        if (FFlag::LuauPreserveUnionIntersectionNodeForLeadingTokenSingleType)
+        {
+            if (un->types.size == 1)
+                return resolveType(scope, *un->types.data[0]);
+        }
+
         std::vector<TypeId> types;
         for (AstType* ann : un->types)
             types.push_back(resolveType(scope, *ann));
@@ -5713,12 +5740,22 @@ TypeId TypeChecker::resolveTypeWorker(const ScopePtr& scope, const AstType& anno
     }
     else if (const auto& un = annotation.as<AstTypeIntersection>())
     {
+        if (FFlag::LuauPreserveUnionIntersectionNodeForLeadingTokenSingleType)
+        {
+            if (un->types.size == 1)
+                return resolveType(scope, *un->types.data[0]);
+        }
+
         std::vector<TypeId> types;
         for (AstType* ann : un->types)
             types.push_back(resolveType(scope, *ann));
 
         return addType(IntersectionType{types});
     }
+    else if (const auto& g = annotation.as<AstTypeGroup>())
+    {
+        return resolveType(scope, *g->type);
+    }
     else if (const auto& tsb = annotation.as<AstTypeSingletonBool>())
     {
         return singletonType(tsb->value);

Analysis/src/TypeUtils.cpp

@@ -5,12 +5,15 @@
 #include "Luau/Normalize.h"
 #include "Luau/Scope.h"
 #include "Luau/ToString.h"
+#include "Luau/Type.h"
 #include "Luau/TypeInfer.h"
 
 #include <algorithm>
 
 LUAU_FASTFLAG(LuauSolverV2);
 LUAU_FASTFLAG(LuauAutocompleteRefactorsForIncrementalAutocomplete);
+LUAU_FASTFLAG(LuauTrackInteriorFreeTypesOnScope);
+LUAU_FASTFLAG(LuauFreeTypesMustHaveBounds)
 
 namespace Luau
 {
@@ -318,9 +321,11 @@ TypePack extendTypePack(
                     {
                         FreeType ft{ftp->scope, builtinTypes->neverType, builtinTypes->unknownType};
                         t = arena.addType(ft);
+                        if (FFlag::LuauTrackInteriorFreeTypesOnScope)
+                            trackInteriorFreeType(ftp->scope, t);
                     }
                     else
-                        t = arena.freshType(ftp->scope);
+                        t = FFlag::LuauFreeTypesMustHaveBounds ? arena.freshType(builtinTypes, ftp->scope) : arena.freshType_DEPRECATED(ftp->scope);
                 }
 
                 newPack.head.push_back(t);
@@ -533,7 +538,7 @@ std::vector<TypeId> findBlockedArgTypesIn(AstExprCall* expr, NotNull<DenseHashMa
 {
     std::vector<TypeId> toBlock;
     BlockedTypeInLiteralVisitor v{astTypes, NotNull{&toBlock}};
-    for (auto arg: expr->args)
+    for (auto arg : expr->args)
     {
         if (isLiteral(arg) || arg->is<AstExprGroup>())
         {
@@ -543,5 +548,21 @@ std::vector<TypeId> findBlockedArgTypesIn(AstExprCall* expr, NotNull<DenseHashMa
     return toBlock;
 }
 
+void trackInteriorFreeType(Scope* scope, TypeId ty)
+{
+    LUAU_ASSERT(FFlag::LuauSolverV2 && FFlag::LuauTrackInteriorFreeTypesOnScope);
+    for (; scope; scope = scope->parent.get())
+    {
+        if (scope->interiorFreeTypes)
+        {
+            scope->interiorFreeTypes->push_back(ty);
+            return;
+        }
+    }
+    // There should at least be *one* generalization constraint per module
+    // where `interiorFreeTypes` is present, which would be the one made
+    // by ConstraintGenerator::visitModuleRoot.
+    LUAU_ASSERT(!"No scopes in parent chain had a present `interiorFreeTypes` member.");
+}
 
 } // namespace Luau

Analysis/src/Unifier.cpp

@@ -22,6 +22,7 @@ LUAU_FASTFLAGVARIABLE(LuauTransitiveSubtyping)
 LUAU_FASTFLAG(LuauSolverV2)
 LUAU_FASTFLAGVARIABLE(LuauFixIndexerSubtypingOrdering)
 LUAU_FASTFLAGVARIABLE(LuauUnifierRecursionOnRestart)
+LUAU_FASTFLAG(LuauFreeTypesMustHaveBounds)
 
 namespace Luau
 {
@@ -1648,7 +1649,7 @@ void Unifier::tryUnify_(TypePackId subTp, TypePackId superTp, bool isFunctionCal
             if (FFlag::LuauSolverV2)
                 return freshType(NotNull{types}, builtinTypes, scope);
             else
-                return types->freshType(scope, level);
+                return FFlag::LuauFreeTypesMustHaveBounds ? types->freshType(builtinTypes, scope, level) : types->freshType_DEPRECATED(scope, level);
         };
 
         const TypePackId emptyTp = types->addTypePack(TypePack{{}, std::nullopt});

Ast/include/Luau/Allocator.h

@@ -45,4 +45,4 @@ private:
     size_t offset;
 };
 
-}
+} // namespace Luau

Ast/include/Luau/Ast.h

@@ -1204,6 +1204,18 @@ public:
     const AstArray<char> value;
 };
 
+class AstTypeGroup : public AstType
+{
+public:
+    LUAU_RTTI(AstTypeGroup)
+
+    explicit AstTypeGroup(const Location& location, AstType* type);
+
+    void visit(AstVisitor* visitor) override;
+
+    AstType* type;
+};
+
 class AstTypePack : public AstNode
 {
 public:
@@ -1470,6 +1482,10 @@ public:
     {
         return visit(static_cast<AstType*>(node));
     }
+    virtual bool visit(class AstTypeGroup* node)
+    {
+        return visit(static_cast<AstType*>(node));
+    }
     virtual bool visit(class AstTypeError* node)
     {
         return visit(static_cast<AstType*>(node));

Ast/include/Luau/Cst.h

@@ -0,0 +1,334 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#pragma once
+
+#include "Luau/Location.h"
+
+#include <string>
+
+namespace Luau
+{
+
+extern int gCstRttiIndex;
+
+template<typename T>
+struct CstRtti
+{
+    static const int value;
+};
+
+template<typename T>
+const int CstRtti<T>::value = ++gCstRttiIndex;
+
+#define LUAU_CST_RTTI(Class) \
+    static int CstClassIndex() \
+    { \
+        return CstRtti<Class>::value; \
+    }
+
+class CstNode
+{
+public:
+    explicit CstNode(int classIndex)
+        : classIndex(classIndex)
+    {
+    }
+
+    template<typename T>
+    bool is() const
+    {
+        return classIndex == T::CstClassIndex();
+    }
+    template<typename T>
+    T* as()
+    {
+        return classIndex == T::CstClassIndex() ? static_cast<T*>(this) : nullptr;
+    }
+    template<typename T>
+    const T* as() const
+    {
+        return classIndex == T::CstClassIndex() ? static_cast<const T*>(this) : nullptr;
+    }
+
+    const int classIndex;
+};
+
+class CstExprConstantNumber : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstExprConstantNumber)
+
+    explicit CstExprConstantNumber(const AstArray<char>& value);
+
+    AstArray<char> value;
+};
+
+class CstExprConstantString : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstExprConstantNumber)
+
+    enum QuoteStyle
+    {
+        QuotedSingle,
+        QuotedDouble,
+        QuotedRaw,
+        QuotedInterp,
+    };
+
+    CstExprConstantString(AstArray<char> sourceString, QuoteStyle quoteStyle, unsigned int blockDepth);
+
+    AstArray<char> sourceString;
+    QuoteStyle quoteStyle;
+    unsigned int blockDepth;
+};
+
+class CstExprCall : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstExprCall)
+
+    CstExprCall(std::optional<Position> openParens, std::optional<Position> closeParens, AstArray<Position> commaPositions);
+
+    std::optional<Position> openParens;
+    std::optional<Position> closeParens;
+    AstArray<Position> commaPositions;
+};
+
+class CstExprIndexExpr : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstExprIndexExpr)
+
+    CstExprIndexExpr(Position openBracketPosition, Position closeBracketPosition);
+
+    Position openBracketPosition;
+    Position closeBracketPosition;
+};
+
+class CstExprTable : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstExprTable)
+
+    enum Separator
+    {
+        Comma,
+        Semicolon,
+    };
+
+    struct Item
+    {
+        std::optional<Position> indexerOpenPosition;  // '[', only if Kind == General
+        std::optional<Position> indexerClosePosition; // ']', only if Kind == General
+        std::optional<Position> equalsPosition;       // only if Kind != List
+        std::optional<Separator> separator;           // may be missing for last Item
+        std::optional<Position> separatorPosition;
+    };
+
+    explicit CstExprTable(const AstArray<Item>& items);
+
+    AstArray<Item> items;
+};
+
+// TODO: Shared between unary and binary, should we split?
+class CstExprOp : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstExprOp)
+
+    explicit CstExprOp(Position opPosition);
+
+    Position opPosition;
+};
+
+class CstExprIfElse : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstExprIfElse)
+
+    CstExprIfElse(Position thenPosition, Position elsePosition, bool isElseIf);
+
+    Position thenPosition;
+    Position elsePosition;
+    bool isElseIf;
+};
+
+class CstExprInterpString : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstExprInterpString)
+
+    explicit CstExprInterpString(AstArray<AstArray<char>> sourceStrings, AstArray<Position> stringPositions);
+
+    AstArray<AstArray<char>> sourceStrings;
+    AstArray<Position> stringPositions;
+};
+
+class CstStatDo : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstStatDo)
+
+    explicit CstStatDo(Position endPosition);
+
+    Position endPosition;
+};
+
+class CstStatRepeat : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstStatRepeat)
+
+    explicit CstStatRepeat(Position untilPosition);
+
+    Position untilPosition;
+};
+
+class CstStatReturn : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstStatReturn)
+
+    explicit CstStatReturn(AstArray<Position> commaPositions);
+
+    AstArray<Position> commaPositions;
+};
+
+class CstStatLocal : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstStatLocal)
+
+    CstStatLocal(AstArray<Position> varsCommaPositions, AstArray<Position> valuesCommaPositions);
+
+    AstArray<Position> varsCommaPositions;
+    AstArray<Position> valuesCommaPositions;
+};
+
+class CstStatFor : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstStatFor)
+
+    CstStatFor(Position equalsPosition, Position endCommaPosition, std::optional<Position> stepCommaPosition);
+
+    Position equalsPosition;
+    Position endCommaPosition;
+    std::optional<Position> stepCommaPosition;
+};
+
+class CstStatForIn : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstStatForIn)
+
+    CstStatForIn(AstArray<Position> varsCommaPositions, AstArray<Position> valuesCommaPositions);
+
+    AstArray<Position> varsCommaPositions;
+    AstArray<Position> valuesCommaPositions;
+};
+
+class CstStatAssign : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstStatAssign)
+
+    CstStatAssign(AstArray<Position> varsCommaPositions, Position equalsPosition, AstArray<Position> valuesCommaPositions);
+
+    AstArray<Position> varsCommaPositions;
+    Position equalsPosition;
+    AstArray<Position> valuesCommaPositions;
+};
+
+class CstStatCompoundAssign : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstStatCompoundAssign)
+
+    explicit CstStatCompoundAssign(Position opPosition);
+
+    Position opPosition;
+};
+
+class CstStatLocalFunction : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstStatLocalFunction)
+
+    explicit CstStatLocalFunction(Position functionKeywordPosition);
+
+    Position functionKeywordPosition;
+};
+
+class CstTypeReference : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstTypeReference)
+
+    CstTypeReference(
+        std::optional<Position> prefixPointPosition,
+        Position openParametersPosition,
+        AstArray<Position> parametersCommaPositions,
+        Position closeParametersPosition
+    );
+
+    std::optional<Position> prefixPointPosition;
+    Position openParametersPosition;
+    AstArray<Position> parametersCommaPositions;
+    Position closeParametersPosition;
+};
+
+class CstTypeTable : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstTypeTable)
+
+    struct Item
+    {
+        enum struct Kind
+        {
+            Indexer,
+            Property,
+            StringProperty,
+        };
+
+        Kind kind;
+        Position indexerOpenPosition;  // '[', only if Kind != Property
+        Position indexerClosePosition; // ']' only if Kind != Property
+        Position colonPosition;
+        std::optional<CstExprTable::Separator> separator; // may be missing for last Item
+        std::optional<Position> separatorPosition;
+
+        CstExprConstantString* stringInfo = nullptr; // only if Kind == StringProperty
+    };
+
+    CstTypeTable(AstArray<Item> items, bool isArray);
+
+    AstArray<Item> items;
+    bool isArray = false;
+};
+
+class CstTypeTypeof : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstTypeTypeof)
+
+    CstTypeTypeof(Position openPosition, Position closePosition);
+
+    Position openPosition;
+    Position closePosition;
+};
+
+class CstTypeSingletonString : public CstNode
+{
+public:
+    LUAU_CST_RTTI(CstTypeSingletonString)
+
+    CstTypeSingletonString(AstArray<char> sourceString, CstExprConstantString::QuoteStyle quoteStyle, unsigned int blockDepth);
+
+    AstArray<char> sourceString;
+    CstExprConstantString::QuoteStyle quoteStyle;
+    unsigned int blockDepth;
+};
+
+} // namespace Luau

Ast/include/Luau/Lexer.h

@@ -87,6 +87,12 @@ struct Lexeme
         Reserved_END
     };
 
+    enum struct QuoteStyle
+    {
+        Single,
+        Double,
+    };
+
     Type type;
     Location location;
 
@@ -111,6 +117,8 @@ public:
     Lexeme(const Location& location, Type type, const char* name);
 
     unsigned int getLength() const;
+    unsigned int getBlockDepth() const;
+    QuoteStyle getQuoteStyle() const;
 
     std::string toString() const;
 };
@@ -230,17 +238,6 @@ private:
     bool skipComments;
     bool readNames;
 
-    // This offset represents a column offset to be applied to any positions created by the lexer until the next new line.
-    // For example:
-    //     local x = 4
-    //     local y = 5
-    // If we start lexing from the position of `l` in `local x = 4`, the line number will be 1, and the column will be 4
-    // However, because the lexer calculates line offsets by 'index in source buffer where there is a newline', the column
-    // count will start at 0. For this reason, for just the first line, we'll need to store the offset.
-    unsigned int lexResumeOffset;
-
-
-
     enum class BraceType
     {
         InterpolatedString,

Ast/include/Luau/Location.h

@@ -14,12 +14,37 @@ struct Position
     {
     }
 
-    bool operator==(const Position& rhs) const;
-    bool operator!=(const Position& rhs) const;
-    bool operator<(const Position& rhs) const;
-    bool operator>(const Position& rhs) const;
-    bool operator<=(const Position& rhs) const;
-    bool operator>=(const Position& rhs) const;
+    bool operator==(const Position& rhs) const
+    {
+        return this->column == rhs.column && this->line == rhs.line;
+    }
+
+    bool operator!=(const Position& rhs) const
+    {
+        return !(*this == rhs);
+    }
+    bool operator<(const Position& rhs) const
+    {
+        if (line == rhs.line)
+            return column < rhs.column;
+        else
+            return line < rhs.line;
+    }
+    bool operator>(const Position& rhs) const
+    {
+        if (line == rhs.line)
+            return column > rhs.column;
+        else
+            return line > rhs.line;
+    }
+    bool operator<=(const Position& rhs) const
+    {
+        return *this == rhs || *this < rhs;
+    }
+    bool operator>=(const Position& rhs) const
+    {
+        return *this == rhs || *this > rhs;
+    }
 
     void shift(const Position& start, const Position& oldEnd, const Position& newEnd);
 };
@@ -52,8 +77,14 @@ struct Location
     {
     }
 
-    bool operator==(const Location& rhs) const;
-    bool operator!=(const Location& rhs) const;
+    bool operator==(const Location& rhs) const
+    {
+        return this->begin == rhs.begin && this->end == rhs.end;
+    }
+    bool operator!=(const Location& rhs) const
+    {
+        return !(*this == rhs);
+    }
 
     bool encloses(const Location& l) const;
     bool overlaps(const Location& l) const;

Ast/include/Luau/ParseOptions.h

@@ -29,6 +29,8 @@ struct ParseOptions
     bool allowDeclarationSyntax = false;
     bool captureComments = false;
     std::optional<FragmentParseResumeSettings> parseFragment = std::nullopt;
+    bool storeCstData = false;
+    bool noErrorLimit = false;
 };
 
 } // namespace Luau

Ast/include/Luau/ParseResult.h

@@ -10,6 +10,7 @@ namespace Luau
 {
 
 class AstStatBlock;
+class CstNode;
 
 class ParseError : public std::exception
 {
@@ -55,6 +56,8 @@ struct Comment
     Location location;
 };
 
+using CstNodeMap = DenseHashMap<AstNode*, CstNode*>;
+
 struct ParseResult
 {
     AstStatBlock* root;
@@ -64,6 +67,8 @@ struct ParseResult
     std::vector<ParseError> errors;
 
     std::vector<Comment> commentLocations;
+
+    CstNodeMap cstNodeMap{nullptr};
 };
 
 static constexpr const char* kParseNameError = "%error-id%";

Ast/include/Luau/Parser.h

@@ -8,6 +8,7 @@
 #include "Luau/StringUtils.h"
 #include "Luau/DenseHash.h"
 #include "Luau/Common.h"
+#include "Luau/Cst.h"
 
 #include <initializer_list>
 #include <optional>
@@ -116,7 +117,7 @@ private:
     AstStat* parseFor();
 
     // funcname ::= Name {`.' Name} [`:' Name]
-    AstExpr* parseFunctionName(Location start, bool& hasself, AstName& debugname);
+    AstExpr* parseFunctionName(Location start_DEPRECATED, bool& hasself, AstName& debugname);
 
     // function funcname funcbody
     LUAU_FORCEINLINE AstStat* parseFunctionStat(const AstArray<AstAttr*>& attributes = {nullptr, 0});
@@ -173,14 +174,18 @@ private:
     );
 
     // explist ::= {exp `,'} exp
-    void parseExprList(TempVector<AstExpr*>& result);
+    void parseExprList(TempVector<AstExpr*>& result, TempVector<Position>* commaPositions = nullptr);
 
     // binding ::= Name [`:` Type]
     Binding parseBinding();
 
     // bindinglist ::= (binding | `...') {`,' bindinglist}
     // Returns the location of the vararg ..., or std::nullopt if the function is not vararg.
-    std::tuple<bool, Location, AstTypePack*> parseBindingList(TempVector<Binding>& result, bool allowDot3 = false);
+    std::tuple<bool, Location, AstTypePack*> parseBindingList(
+        TempVector<Binding>& result,
+        bool allowDot3 = false,
+        TempVector<Position>* commaPositions = nullptr
+    );
 
     AstType* parseOptionalType();
 
@@ -201,7 +206,17 @@ private:
     std::optional<AstTypeList> parseOptionalReturnType();
     std::pair<Location, AstTypeList> parseReturnType();
 
-    AstTableIndexer* parseTableIndexer(AstTableAccess access, std::optional<Location> accessLocation);
+    struct TableIndexerResult
+    {
+        AstTableIndexer* node;
+        Position indexerOpenPosition;
+        Position indexerClosePosition;
+        Position colonPosition;
+    };
+
+    TableIndexerResult parseTableIndexer(AstTableAccess access, std::optional<Location> accessLocation);
+    // Remove with FFlagLuauStoreCSTData
+    AstTableIndexer* parseTableIndexer_DEPRECATED(AstTableAccess access, std::optional<Location> accessLocation);
 
     AstTypeOrPack parseFunctionType(bool allowPack, const AstArray<AstAttr*>& attributes);
     AstType* parseFunctionTypeTail(
@@ -259,6 +274,8 @@ private:
     // args ::=  `(' [explist] `)' | tableconstructor | String
     AstExpr* parseFunctionArgs(AstExpr* func, bool self);
 
+    std::optional<CstExprTable::Separator> tableSeparator();
+
     // tableconstructor ::= `{' [fieldlist] `}'
     // fieldlist ::= field {fieldsep field} [fieldsep]
     // field ::= `[' exp `]' `=' exp | Name `=' exp | exp
@@ -280,9 +297,13 @@ private:
     std::pair<AstArray<AstGenericType>, AstArray<AstGenericTypePack>> parseGenericTypeList(bool withDefaultValues);
 
     // `<' Type[, ...] `>'
-    AstArray<AstTypeOrPack> parseTypeParams();
+    AstArray<AstTypeOrPack> parseTypeParams(
+        Position* openingPosition = nullptr,
+        TempVector<Position>* commaPositions = nullptr,
+        Position* closingPosition = nullptr
+    );
 
-    std::optional<AstArray<char>> parseCharArray();
+    std::optional<AstArray<char>> parseCharArray(AstArray<char>* originalString = nullptr);
     AstExpr* parseString();
     AstExpr* parseNumber();
 
@@ -292,6 +313,9 @@ private:
 
     void restoreLocals(unsigned int offset);
 
+    /// Returns string quote style and block depth
+    std::pair<CstExprConstantString::QuoteStyle, unsigned int> extractStringDetails();
+
     // check that parser is at lexeme/symbol, move to next lexeme/symbol on success, report failure and continue on failure
     bool expectAndConsume(char value, const char* context = nullptr);
     bool expectAndConsume(Lexeme::Type type, const char* context = nullptr);
@@ -435,6 +459,7 @@ private:
     std::vector<AstAttr*> scratchAttr;
     std::vector<AstStat*> scratchStat;
     std::vector<AstArray<char>> scratchString;
+    std::vector<AstArray<char>> scratchString2;
     std::vector<AstExpr*> scratchExpr;
     std::vector<AstExpr*> scratchExprAux;
     std::vector<AstName> scratchName;
@@ -442,15 +467,20 @@ private:
     std::vector<Binding> scratchBinding;
     std::vector<AstLocal*> scratchLocal;
     std::vector<AstTableProp> scratchTableTypeProps;
+    std::vector<CstTypeTable::Item> scratchCstTableTypeProps;
     std::vector<AstType*> scratchType;
     std::vector<AstTypeOrPack> scratchTypeOrPack;
     std::vector<AstDeclaredClassProp> scratchDeclaredClassProps;
     std::vector<AstExprTable::Item> scratchItem;
+    std::vector<CstExprTable::Item> scratchCstItem;
     std::vector<AstArgumentName> scratchArgName;
     std::vector<AstGenericType> scratchGenericTypes;
     std::vector<AstGenericTypePack> scratchGenericTypePacks;
     std::vector<std::optional<AstArgumentName>> scratchOptArgName;
+    std::vector<Position> scratchPosition;
     std::string scratchData;
+
+    CstNodeMap cstNodeMap;
 };
 
 } // namespace Luau

Ast/src/Allocator.cpp

@@ -63,4 +63,4 @@ void* Allocator::allocate(size_t size)
     return page->data;
 }
 
-}
+} // namespace Luau

Ast/src/Ast.cpp

@@ -1091,6 +1091,18 @@ void AstTypeSingletonString::visit(AstVisitor* visitor)
     visitor->visit(this);
 }
 
+AstTypeGroup::AstTypeGroup(const Location& location, AstType* type)
+    : AstType(ClassIndex(), location)
+    , type(type)
+{
+}
+
+void AstTypeGroup::visit(AstVisitor* visitor)
+{
+    if (visitor->visit(this))
+        type->visit(visitor);
+}
+
 AstTypeError::AstTypeError(const Location& location, const AstArray<AstType*>& types, bool isMissing, unsigned messageIndex)
     : AstType(ClassIndex(), location)
     , types(types)
@@ -1151,10 +1163,7 @@ void AstTypePackGeneric::visit(AstVisitor* visitor)
 
 bool isLValue(const AstExpr* expr)
 {
-    return expr->is<AstExprLocal>()
-        || expr->is<AstExprGlobal>()
-        || expr->is<AstExprIndexName>()
-        || expr->is<AstExprIndexExpr>();
+    return expr->is<AstExprLocal>() || expr->is<AstExprGlobal>() || expr->is<AstExprIndexName>() || expr->is<AstExprIndexExpr>();
 }
 
 AstName getIdentifier(AstExpr* node)

Ast/src/Cst.cpp

@@ -0,0 +1,169 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#include "Luau/Ast.h"
+#include "Luau/Cst.h"
+#include "Luau/Common.h"
+
+namespace Luau
+{
+
+int gCstRttiIndex = 0;
+
+CstExprConstantNumber::CstExprConstantNumber(const AstArray<char>& value)
+    : CstNode(CstClassIndex())
+    , value(value)
+{
+}
+
+CstExprConstantString::CstExprConstantString(AstArray<char> sourceString, QuoteStyle quoteStyle, unsigned int blockDepth)
+    : CstNode(CstClassIndex())
+    , sourceString(sourceString)
+    , quoteStyle(quoteStyle)
+    , blockDepth(blockDepth)
+{
+    LUAU_ASSERT(blockDepth == 0 || quoteStyle == QuoteStyle::QuotedRaw);
+}
+
+CstExprCall::CstExprCall(std::optional<Position> openParens, std::optional<Position> closeParens, AstArray<Position> commaPositions)
+    : CstNode(CstClassIndex())
+    , openParens(openParens)
+    , closeParens(closeParens)
+    , commaPositions(commaPositions)
+{
+}
+
+CstExprIndexExpr::CstExprIndexExpr(Position openBracketPosition, Position closeBracketPosition)
+    : CstNode(CstClassIndex())
+    , openBracketPosition(openBracketPosition)
+    , closeBracketPosition(closeBracketPosition)
+{
+}
+
+CstExprTable::CstExprTable(const AstArray<Item>& items)
+    : CstNode(CstClassIndex())
+    , items(items)
+{
+}
+
+CstExprOp::CstExprOp(Position opPosition)
+    : CstNode(CstClassIndex())
+    , opPosition(opPosition)
+{
+}
+
+CstExprIfElse::CstExprIfElse(Position thenPosition, Position elsePosition, bool isElseIf)
+    : CstNode(CstClassIndex())
+    , thenPosition(thenPosition)
+    , elsePosition(elsePosition)
+    , isElseIf(isElseIf)
+{
+}
+
+CstExprInterpString::CstExprInterpString(AstArray<AstArray<char>> sourceStrings, AstArray<Position> stringPositions)
+    : CstNode(CstClassIndex())
+    , sourceStrings(sourceStrings)
+    , stringPositions(stringPositions)
+{
+}
+
+CstStatDo::CstStatDo(Position endPosition)
+    : CstNode(CstClassIndex())
+    , endPosition(endPosition)
+{
+}
+
+CstStatRepeat::CstStatRepeat(Position untilPosition)
+    : CstNode(CstClassIndex())
+    , untilPosition(untilPosition)
+{
+}
+
+CstStatReturn::CstStatReturn(AstArray<Position> commaPositions)
+    : CstNode(CstClassIndex())
+    , commaPositions(commaPositions)
+{
+}
+
+CstStatLocal::CstStatLocal(AstArray<Position> varsCommaPositions, AstArray<Position> valuesCommaPositions)
+    : CstNode(CstClassIndex())
+    , varsCommaPositions(varsCommaPositions)
+    , valuesCommaPositions(valuesCommaPositions)
+{
+}
+
+CstStatFor::CstStatFor(Position equalsPosition, Position endCommaPosition, std::optional<Position> stepCommaPosition)
+    : CstNode(CstClassIndex())
+    , equalsPosition(equalsPosition)
+    , endCommaPosition(endCommaPosition)
+    , stepCommaPosition(stepCommaPosition)
+{
+}
+
+CstStatForIn::CstStatForIn(AstArray<Position> varsCommaPositions, AstArray<Position> valuesCommaPositions)
+    : CstNode(CstClassIndex())
+    , varsCommaPositions(varsCommaPositions)
+    , valuesCommaPositions(valuesCommaPositions)
+{
+}
+
+CstStatAssign::CstStatAssign(
+    AstArray<Position> varsCommaPositions,
+    Position equalsPosition,
+    AstArray<Position> valuesCommaPositions
+)
+    : CstNode(CstClassIndex())
+    , varsCommaPositions(varsCommaPositions)
+    , equalsPosition(equalsPosition)
+    , valuesCommaPositions(valuesCommaPositions)
+{
+}
+
+CstStatCompoundAssign::CstStatCompoundAssign(Position opPosition)
+    : CstNode(CstClassIndex())
+    , opPosition(opPosition)
+{
+}
+
+CstStatLocalFunction::CstStatLocalFunction(Position functionKeywordPosition)
+    : CstNode(CstClassIndex())
+    , functionKeywordPosition(functionKeywordPosition)
+{
+}
+
+CstTypeReference::CstTypeReference(
+    std::optional<Position> prefixPointPosition,
+    Position openParametersPosition,
+    AstArray<Position> parametersCommaPositions,
+    Position closeParametersPosition
+)
+    : CstNode(CstClassIndex())
+    , prefixPointPosition(prefixPointPosition)
+    , openParametersPosition(openParametersPosition)
+    , parametersCommaPositions(parametersCommaPositions)
+    , closeParametersPosition(closeParametersPosition)
+{
+}
+
+CstTypeTable::CstTypeTable(AstArray<Item> items, bool isArray)
+    : CstNode(CstClassIndex())
+    , items(items)
+    , isArray(isArray)
+{
+}
+
+CstTypeTypeof::CstTypeTypeof(Position openPosition, Position closePosition)
+    : CstNode(CstClassIndex())
+    , openPosition(openPosition)
+    , closePosition(closePosition)
+{
+}
+
+CstTypeSingletonString::CstTypeSingletonString(AstArray<char> sourceString, CstExprConstantString::QuoteStyle quoteStyle, unsigned int blockDepth)
+    : CstNode(CstClassIndex())
+    , sourceString(sourceString)
+    , quoteStyle(quoteStyle)
+    , blockDepth(blockDepth)
+{
+    LUAU_ASSERT(quoteStyle != CstExprConstantString::QuotedInterp);
+}
+
+} // namespace Luau

Ast/src/Lexer.cpp

@@ -8,7 +8,9 @@
 
 #include <limits.h>
 
-LUAU_FASTFLAGVARIABLE(LexerResumesFromPosition)
+LUAU_FASTFLAGVARIABLE(LexerResumesFromPosition2)
+LUAU_FASTFLAGVARIABLE(LexerFixInterpStringStart)
+
 namespace Luau
 {
 
@@ -304,20 +306,51 @@ static char unescape(char ch)
     }
 }
 
+unsigned int Lexeme::getBlockDepth() const
+{
+    LUAU_ASSERT(type == Lexeme::RawString || type == Lexeme::BlockComment);
+
+    // If we have a well-formed string, we are guaranteed to see 2 `]` characters after the end of the string contents
+    LUAU_ASSERT(*(data + length) == ']');
+    unsigned int depth = 0;
+    do
+    {
+        depth++;
+    } while (*(data + length + depth) != ']');
+
+    return depth - 1;
+}
+
+Lexeme::QuoteStyle Lexeme::getQuoteStyle() const
+{
+    LUAU_ASSERT(type == Lexeme::QuotedString);
+
+    // If we have a well-formed string, we are guaranteed to see a closing delimiter after the string
+    LUAU_ASSERT(data);
+
+    char quote = *(data + length);
+    if (quote == '\'')
+        return Lexeme::QuoteStyle::Single;
+    else if (quote == '"')
+        return Lexeme::QuoteStyle::Double;
+
+    LUAU_ASSERT(!"Unknown quote style");
+    return Lexeme::QuoteStyle::Double; // unreachable, but required due to compiler warning
+}
+
 Lexer::Lexer(const char* buffer, size_t bufferSize, AstNameTable& names, Position startPosition)
     : buffer(buffer)
     , bufferSize(bufferSize)
     , offset(0)
-    , line(FFlag::LexerResumesFromPosition ? startPosition.line : 0)
-    , lineOffset(0)
+    , line(FFlag::LexerResumesFromPosition2 ? startPosition.line : 0)
+    , lineOffset(FFlag::LexerResumesFromPosition2 ? 0u - startPosition.column : 0)
     , lexeme(
-          (FFlag::LexerResumesFromPosition ? Location(Position(startPosition.line, startPosition.column), 0) : Location(Position(0, 0), 0)),
+          (FFlag::LexerResumesFromPosition2 ? Location(Position(startPosition.line, startPosition.column), 0) : Location(Position(0, 0), 0)),
           Lexeme::Eof
       )
     , names(names)
     , skipComments(false)
     , readNames(true)
-    , lexResumeOffset(FFlag::LexerResumesFromPosition ? startPosition.column : 0)
 {
 }
 
@@ -372,7 +405,6 @@ Lexeme Lexer::lookahead()
     Location currentPrevLocation = prevLocation;
     size_t currentBraceStackSize = braceStack.size();
     BraceType currentBraceType = braceStack.empty() ? BraceType::Normal : braceStack.back();
-    unsigned int currentLexResumeOffset = lexResumeOffset;
 
     Lexeme result = next();
 
@@ -381,7 +413,6 @@ Lexeme Lexer::lookahead()
     lineOffset = currentLineOffset;
     lexeme = currentLexeme;
     prevLocation = currentPrevLocation;
-    lexResumeOffset = currentLexResumeOffset;
 
     if (braceStack.size() < currentBraceStackSize)
         braceStack.push_back(currentBraceType);
@@ -412,9 +443,10 @@ char Lexer::peekch(unsigned int lookahead) const
     return (offset + lookahead < bufferSize) ? buffer[offset + lookahead] : 0;
 }
 
+LUAU_FORCEINLINE
 Position Lexer::position() const
 {
-    return Position(line, offset - lineOffset + (FFlag::LexerResumesFromPosition ? lexResumeOffset : 0));
+    return Position(line, offset - lineOffset);
 }
 
 LUAU_FORCEINLINE
@@ -433,9 +465,6 @@ void Lexer::consumeAny()
     {
         line++;
         lineOffset = offset + 1;
-        // every new line, we reset
-        if (FFlag::LexerResumesFromPosition)
-            lexResumeOffset = 0;
     }
 
     offset++;
@@ -764,7 +793,7 @@ Lexeme Lexer::readNext()
             return Lexeme(Location(start, 1), '}');
         }
 
-        return readInterpolatedStringSection(position(), Lexeme::InterpStringMid, Lexeme::InterpStringEnd);
+        return readInterpolatedStringSection(FFlag::LexerFixInterpStringStart ? start : position(), Lexeme::InterpStringMid, Lexeme::InterpStringEnd);
     }
 
     case '=':

Ast/src/Location.cpp

@@ -4,42 +4,6 @@
 namespace Luau
 {
 
-bool Position::operator==(const Position& rhs) const
-{
-    return this->column == rhs.column && this->line == rhs.line;
-}
-
-bool Position::operator!=(const Position& rhs) const
-{
-    return !(*this == rhs);
-}
-
-bool Position::operator<(const Position& rhs) const
-{
-    if (line == rhs.line)
-        return column < rhs.column;
-    else
-        return line < rhs.line;
-}
-
-bool Position::operator>(const Position& rhs) const
-{
-    if (line == rhs.line)
-        return column > rhs.column;
-    else
-        return line > rhs.line;
-}
-
-bool Position::operator<=(const Position& rhs) const
-{
-    return *this == rhs || *this < rhs;
-}
-
-bool Position::operator>=(const Position& rhs) const
-{
-    return *this == rhs || *this > rhs;
-}
-
 void Position::shift(const Position& start, const Position& oldEnd, const Position& newEnd)
 {
     if (*this >= start)
@@ -54,16 +18,6 @@ void Position::shift(const Position& start, const Position& oldEnd, const Positi
     }
 }
 
-bool Location::operator==(const Location& rhs) const
-{
-    return this->begin == rhs.begin && this->end == rhs.end;
-}
-
-bool Location::operator!=(const Location& rhs) const
-{
-    return !(*this == rhs);
-}
-
 bool Location::encloses(const Location& l) const
 {
     return begin <= l.begin && end >= l.end;

CLI/include/Luau/FileUtils.h

@@ -10,7 +10,7 @@
 std::optional<std::string> getCurrentWorkingDirectory();
 
 std::string normalizePath(std::string_view path);
-std::string resolvePath(std::string_view relativePath, std::string_view baseFilePath);
+std::optional<std::string> resolvePath(std::string_view relativePath, std::string_view baseFilePath);
 
 std::optional<std::string> readFile(const std::string& name);
 std::optional<std::string> readStdin();
@@ -23,7 +23,7 @@ bool isDirectory(const std::string& path);
 bool traverseDirectory(const std::string& path, const std::function<void(const std::string& name)>& callback);
 
 std::vector<std::string_view> splitPath(std::string_view path);
-std::string joinPaths(const std::string& lhs, const std::string& rhs);
-std::optional<std::string> getParentPath(const std::string& path);
+std::string joinPaths(std::string_view lhs, std::string_view rhs);
+std::optional<std::string> getParentPath(std::string_view path);
 
 std::vector<std::string> getSourceFiles(int argc, char** argv);

CLI/src/Analyze.cpp

@@ -7,9 +7,9 @@
 #include "Luau/TypeAttach.h"
 #include "Luau/Transpiler.h"
 
-#include "FileUtils.h"
-#include "Flags.h"
-#include "Require.h"
+#include "Luau/FileUtils.h"
+#include "Luau/Flags.h"
+#include "Luau/Require.h"
 
 #include <condition_variable>
 #include <functional>

CLI/src/Ast.cpp

@@ -8,7 +8,7 @@
 #include "Luau/ParseOptions.h"
 #include "Luau/ToString.h"
 
-#include "FileUtils.h"
+#include "Luau/FileUtils.h"
 
 static void displayHelp(const char* argv0)
 {

CLI/src/Bytecode.cpp

@@ -7,8 +7,8 @@
 #include "Luau/BytecodeBuilder.h"
 #include "Luau/Parser.h"
 #include "Luau/BytecodeSummary.h"
-#include "FileUtils.h"
-#include "Flags.h"
+#include "Luau/FileUtils.h"
+#include "Luau/Flags.h"
 
 #include <memory>
 

CLI/src/Compile.cpp

@@ -8,8 +8,8 @@
 #include "Luau/Parser.h"
 #include "Luau/TimeTrace.h"
 
-#include "FileUtils.h"
-#include "Flags.h"
+#include "Luau/FileUtils.h"
+#include "Luau/Flags.h"
 
 #include <memory>
 
@@ -341,7 +341,8 @@ static bool compileFile(const char* name, CompileFormat format, Luau::CodeGen::A
             bcb.setDumpFlags(Luau::BytecodeBuilder::Dump_Source | Luau::BytecodeBuilder::Dump_Remarks);
             bcb.setDumpSource(*source);
         }
-        else if (format == CompileFormat::Codegen || format == CompileFormat::CodegenAsm || format == CompileFormat::CodegenIr || format == CompileFormat::CodegenVerbose)
+        else if (format == CompileFormat::Codegen || format == CompileFormat::CodegenAsm || format == CompileFormat::CodegenIr ||
+                 format == CompileFormat::CodegenVerbose)
         {
             bcb.setDumpFlags(
                 Luau::BytecodeBuilder::Dump_Code | Luau::BytecodeBuilder::Dump_Source | Luau::BytecodeBuilder::Dump_Locals |

CLI/src/Coverage.cpp

@@ -1,5 +1,5 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Coverage.h"
+#include "Luau/Coverage.h"
 
 #include "lua.h"
 

CLI/src/FileUtils.cpp

@@ -1,5 +1,5 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "FileUtils.h"
+#include "Luau/FileUtils.h"
 
 #include "Luau/Common.h"
 
@@ -20,6 +20,7 @@
 #endif
 
 #include <string.h>
+#include <string_view>
 
 #ifdef _WIN32
 static std::wstring fromUtf8(const std::string& path)
@@ -90,108 +91,76 @@ std::optional<std::string> getCurrentWorkingDirectory()
     return std::nullopt;
 }
 
-// Returns the normal/canonical form of a path (e.g. "../subfolder/../module.luau" -> "../module.luau")
 std::string normalizePath(std::string_view path)
 {
-    return resolvePath(path, "");
-}
+    const std::vector<std::string_view> components = splitPath(path);
+    std::vector<std::string_view> normalizedComponents;
 
-// Takes a path that is relative to the file at baseFilePath and returns the path explicitly rebased onto baseFilePath.
-// For absolute paths, baseFilePath will be ignored, and this function will resolve the path to a canonical path:
-// (e.g. "/Users/.././Users/johndoe" -> "/Users/johndoe").
-std::string resolvePath(std::string_view path, std::string_view baseFilePath)
-{
-    std::vector<std::string_view> pathComponents;
-    std::vector<std::string_view> baseFilePathComponents;
+    const bool isAbsolute = isAbsolutePath(path);
 
-    // Dependent on whether the final resolved path is absolute or relative
-    // - if relative (when path and baseFilePath are both relative), resolvedPathPrefix remains empty
-    // - if absolute (if either path or baseFilePath are absolute), resolvedPathPrefix is "C:\", "/", etc.
-    std::string resolvedPathPrefix;
-    bool isResolvedPathRelative = false;
-
-    if (isAbsolutePath(path))
-    {
-        // path is absolute, we use path's prefix and ignore baseFilePath
-        size_t afterPrefix = path.find_first_of("\\/") + 1;
-        resolvedPathPrefix = path.substr(0, afterPrefix);
-        pathComponents = splitPath(path.substr(afterPrefix));
-    }
-    else
-    {
-        size_t afterPrefix = baseFilePath.find_first_of("\\/") + 1;
-        baseFilePathComponents = splitPath(baseFilePath.substr(afterPrefix));
-        if (isAbsolutePath(baseFilePath))
-        {
-            // path is relative and baseFilePath is absolute, we use baseFilePath's prefix
-            resolvedPathPrefix = baseFilePath.substr(0, afterPrefix);
-        }
-        else
-        {
-            // path and baseFilePath are both relative, we do not set a prefix (resolved path will be relative)
-            isResolvedPathRelative = true;
-        }
-        pathComponents = splitPath(path);
-    }
-
-    // Remove filename from components
-    if (!baseFilePathComponents.empty())
-        baseFilePathComponents.pop_back();
-
-    // Resolve the path by applying pathComponents to baseFilePathComponents
-    int numPrependedParents = 0;
-    for (std::string_view component : pathComponents)
+    // 1. Normalize path components
+    const size_t startIndex = isAbsolute ? 1 : 0;
+    for (size_t i = startIndex; i < components.size(); i++)
     {
+        std::string_view component = components[i];
         if (component == "..")
         {
-            if (baseFilePathComponents.empty())
+            if (normalizedComponents.empty())
             {
-                if (isResolvedPathRelative)
-                    numPrependedParents++;      // "../" will later be added to the beginning of the resolved path
+                if (!isAbsolute)
+                {
+                    normalizedComponents.emplace_back("..");
+                }
             }
-            else if (baseFilePathComponents.back() != "..")
+            else if (normalizedComponents.back() == "..")
             {
-                baseFilePathComponents.pop_back(); // Resolve cases like "folder/subfolder/../../file" to "file"
+                normalizedComponents.emplace_back("..");
+            }
+            else
+            {
+                normalizedComponents.pop_back();
             }
         }
-        else if (component != "." && !component.empty())
+        else if (!component.empty() && component != ".")
         {
-            baseFilePathComponents.push_back(component);
+            normalizedComponents.emplace_back(component);
         }
     }
 
-    // Create resolved path prefix for relative paths
-    if (isResolvedPathRelative)
+    std::string normalizedPath;
+
+    // 2. Add correct prefix to formatted path
+    if (isAbsolute)
     {
-        if (numPrependedParents > 0)
-        {
-            resolvedPathPrefix.reserve(numPrependedParents * 3);
-            for (int i = 0; i < numPrependedParents; i++)
-            {
-                resolvedPathPrefix += "../";
-            }
-        }
-        else
-        {
-            resolvedPathPrefix = "./";
-        }
+        normalizedPath += components[0];
+        normalizedPath += "/";
+    }
+    else if (normalizedComponents.empty() || normalizedComponents[0] != "..")
+    {
+        normalizedPath += "./";
     }
 
-    // Join baseFilePathComponents to form the resolved path
-    std::string resolvedPath = resolvedPathPrefix;
-    for (auto iter = baseFilePathComponents.begin(); iter != baseFilePathComponents.end(); ++iter)
+    // 3. Join path components to form the normalized path
+    for (auto iter = normalizedComponents.begin(); iter != normalizedComponents.end(); ++iter)
     {
-        if (iter != baseFilePathComponents.begin())
-            resolvedPath += "/";
+        if (iter != normalizedComponents.begin())
+            normalizedPath += "/";
 
-        resolvedPath += *iter;
+        normalizedPath += *iter;
     }
-    if (resolvedPath.size() > resolvedPathPrefix.size() && resolvedPath.back() == '/')
-    {
-        // Remove trailing '/' if present
-        resolvedPath.pop_back();
-    }
-    return resolvedPath;
+    if (normalizedPath.size() >= 2 && normalizedPath[normalizedPath.size() - 1] == '.' && normalizedPath[normalizedPath.size() - 2] == '.')
+        normalizedPath += "/";
+
+    return normalizedPath;
+}
+
+std::optional<std::string> resolvePath(std::string_view path, std::string_view baseFilePath)
+{
+    std::optional<std::string> baseFilePathParent = getParentPath(baseFilePath);
+    if (!baseFilePathParent)
+        return std::nullopt;
+
+    return normalizePath(joinPaths(*baseFilePathParent, path));
 }
 
 bool hasFileExtension(std::string_view name, const std::vector<std::string>& extensions)
@@ -416,16 +385,16 @@ std::vector<std::string_view> splitPath(std::string_view path)
     return components;
 }
 
-std::string joinPaths(const std::string& lhs, const std::string& rhs)
+std::string joinPaths(std::string_view lhs, std::string_view rhs)
 {
-    std::string result = lhs;
+    std::string result = std::string(lhs);
     if (!result.empty() && result.back() != '/' && result.back() != '\\')
         result += '/';
     result += rhs;
     return result;
 }
 
-std::optional<std::string> getParentPath(const std::string& path)
+std::optional<std::string> getParentPath(std::string_view path)
 {
     if (path == "" || path == "." || path == "/")
         return std::nullopt;
@@ -441,7 +410,7 @@ std::optional<std::string> getParentPath(const std::string& path)
         return "/";
 
     if (slash != std::string::npos)
-        return path.substr(0, slash);
+        return std::string(path.substr(0, slash));
 
     return "";
 }
@@ -471,10 +440,12 @@ std::vector<std::string> getSourceFiles(int argc, char** argv)
         if (argv[i][0] == '-' && argv[i][1] != '\0')
             continue;
 
-        if (isDirectory(argv[i]))
+        std::string normalized = normalizePath(argv[i]);
+
+        if (isDirectory(normalized))
         {
             traverseDirectory(
-                argv[i],
+                normalized,
                 [&](const std::string& name)
                 {
                     std::string ext = getExtension(name);
@@ -486,7 +457,7 @@ std::vector<std::string> getSourceFiles(int argc, char** argv)
         }
         else
         {
-            files.push_back(argv[i]);
+            files.push_back(normalized);
         }
     }
 

CLI/src/Reduce.cpp

@@ -5,7 +5,7 @@
 #include "Luau/Parser.h"
 #include "Luau/Transpiler.h"
 
-#include "FileUtils.h"
+#include "Luau/FileUtils.h"
 
 #include <algorithm>
 #include <stdio.h>

CLI/src/Repl.cpp

@@ -1,5 +1,5 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Repl.h"
+#include "Luau/Repl.h"
 
 #include "Luau/Common.h"
 #include "lua.h"
@@ -10,11 +10,11 @@
 #include "Luau/Parser.h"
 #include "Luau/TimeTrace.h"
 
-#include "Coverage.h"
-#include "FileUtils.h"
-#include "Flags.h"
-#include "Profiler.h"
-#include "Require.h"
+#include "Luau/Coverage.h"
+#include "Luau/FileUtils.h"
+#include "Luau/Flags.h"
+#include "Luau/Profiler.h"
+#include "Luau/Require.h"
 
 #include "isocline.h"
 

CLI/src/ReplEntry.cpp

@@ -1,5 +1,5 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Repl.h"
+#include "Luau/Repl.h"
 
 int main(int argc, char** argv)
 {

CLI/src/Require.cpp

@@ -1,7 +1,7 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Require.h"
+#include "Luau/Require.h"
 
-#include "FileUtils.h"
+#include "Luau/FileUtils.h"
 #include "Luau/Common.h"
 #include "Luau/Config.h"
 
@@ -141,8 +141,17 @@ bool RequireResolver::resolveAndStoreDefaultPaths()
             return false;
 
         // resolvePath automatically sanitizes/normalizes the paths
-        resolvedRequire.identifier = resolvePath(pathToResolve, identifierContext);
-        resolvedRequire.absolutePath = resolvePath(pathToResolve, *absolutePathContext);
+        std::optional<std::string> identifier = resolvePath(pathToResolve, identifierContext);
+        std::optional<std::string> absolutePath = resolvePath(pathToResolve, *absolutePathContext);
+
+        if (!identifier || !absolutePath)
+        {
+            errorHandler.reportError("could not resolve require path");
+            return false;
+        }
+
+        resolvedRequire.identifier = std::move(*identifier);
+        resolvedRequire.absolutePath = std::move(*absolutePath);
     }
     else
     {
@@ -181,7 +190,7 @@ std::optional<std::string> RequireResolver::getRequiringContextAbsolute()
         else
         {
             // Require statement is being executed in a file, must resolve relative to CWD
-            requiringFile = resolvePath(requireContext.getPath(), joinPaths(*cwd, "stdin"));
+            requiringFile = normalizePath(joinPaths(*cwd, requireContext.getPath()));
         }
     }
     std::replace(requiringFile.begin(), requiringFile.end(), '\\', '/');
@@ -190,7 +199,7 @@ std::optional<std::string> RequireResolver::getRequiringContextAbsolute()
 
 std::string RequireResolver::getRequiringContextRelative()
 {
-    return requireContext.isStdin() ? "" : requireContext.getPath();
+    return requireContext.isStdin() ? "./" : requireContext.getPath();
 }
 
 bool RequireResolver::substituteAliasIfPresent(std::string& path)
@@ -301,4 +310,4 @@ bool RequireResolver::parseConfigInDirectory(const std::string& directory)
     }
 
     return true;
-}
+}

CMakeLists.txt

@@ -68,11 +68,12 @@ include(Sources.cmake)
 target_include_directories(Luau.Common INTERFACE Common/include)
 
 target_compile_features(Luau.CLI.lib PUBLIC cxx_std_17)
-target_link_libraries(Luau.CLI.lib PRIVATE Luau.Common)
+target_include_directories(Luau.CLI.lib PUBLIC CLI/include)
+target_link_libraries(Luau.CLI.lib PRIVATE Luau.Common Luau.Config)
 
 target_compile_features(Luau.Ast PUBLIC cxx_std_17)
 target_include_directories(Luau.Ast PUBLIC Ast/include)
-target_link_libraries(Luau.Ast PUBLIC Luau.Common Luau.CLI.lib)
+target_link_libraries(Luau.Ast PUBLIC Luau.Common)
 
 target_compile_features(Luau.Compiler PUBLIC cxx_std_17)
 target_include_directories(Luau.Compiler PUBLIC Compiler/include)

CodeGen/include/Luau/AssemblyBuilderX64.h

@@ -160,6 +160,7 @@ public:
     void vmaxsd(OperandX64 dst, OperandX64 src1, OperandX64 src2);
     void vminsd(OperandX64 dst, OperandX64 src1, OperandX64 src2);
 
+    void vcmpeqsd(OperandX64 dst, OperandX64 src1, OperandX64 src2);
     void vcmpltsd(OperandX64 dst, OperandX64 src1, OperandX64 src2);
 
     void vblendvpd(RegisterX64 dst, RegisterX64 src1, OperandX64 mask, RegisterX64 src3);

CodeGen/include/Luau/CodeAllocator.h

@@ -1,7 +1,7 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #pragma once
 
-#include "Luau/CodeGen.h"
+#include "Luau/CodeGenOptions.h"
 
 #include <vector>
 

CodeGen/include/Luau/CodeGen.h

@@ -1,7 +1,10 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #pragma once
 
-#include <algorithm>
+#include "Luau/CodeGenCommon.h"
+#include "Luau/CodeGenOptions.h"
+#include "Luau/LoweringStats.h"
+
 #include <array>
 #include <memory>
 #include <string>
@@ -12,25 +15,11 @@
 
 struct lua_State;
 
-#if defined(__x86_64__) || defined(_M_X64)
-#define CODEGEN_TARGET_X64
-#elif defined(__aarch64__) || defined(_M_ARM64)
-#define CODEGEN_TARGET_A64
-#endif
-
 namespace Luau
 {
 namespace CodeGen
 {
 
-enum CodeGenFlags
-{
-    // Only run native codegen for modules that have been marked with --!native
-    CodeGen_OnlyNativeModules = 1 << 0,
-    // Run native codegen for functions that the compiler considers not profitable
-    CodeGen_ColdFunctions = 1 << 1,
-};
-
 // These enum values can be reported through telemetry.
 // To ensure consistency, changes should be additive.
 enum class CodeGenCompilationResult
@@ -72,106 +61,6 @@ struct CompilationResult
     }
 };
 
-struct IrBuilder;
-struct IrOp;
-
-using HostVectorOperationBytecodeType = uint8_t (*)(const char* member, size_t memberLength);
-using HostVectorAccessHandler = bool (*)(IrBuilder& builder, const char* member, size_t memberLength, int resultReg, int sourceReg, int pcpos);
-using HostVectorNamecallHandler =
-    bool (*)(IrBuilder& builder, const char* member, size_t memberLength, int argResReg, int sourceReg, int params, int results, int pcpos);
-
-enum class HostMetamethod
-{
-    Add,
-    Sub,
-    Mul,
-    Div,
-    Idiv,
-    Mod,
-    Pow,
-    Minus,
-    Equal,
-    LessThan,
-    LessEqual,
-    Length,
-    Concat,
-};
-
-using HostUserdataOperationBytecodeType = uint8_t (*)(uint8_t type, const char* member, size_t memberLength);
-using HostUserdataMetamethodBytecodeType = uint8_t (*)(uint8_t lhsTy, uint8_t rhsTy, HostMetamethod method);
-using HostUserdataAccessHandler =
-    bool (*)(IrBuilder& builder, uint8_t type, const char* member, size_t memberLength, int resultReg, int sourceReg, int pcpos);
-using HostUserdataMetamethodHandler =
-    bool (*)(IrBuilder& builder, uint8_t lhsTy, uint8_t rhsTy, int resultReg, IrOp lhs, IrOp rhs, HostMetamethod method, int pcpos);
-using HostUserdataNamecallHandler = bool (*)(
-    IrBuilder& builder,
-    uint8_t type,
-    const char* member,
-    size_t memberLength,
-    int argResReg,
-    int sourceReg,
-    int params,
-    int results,
-    int pcpos
-);
-
-struct HostIrHooks
-{
-    // Suggest result type of a vector field access
-    HostVectorOperationBytecodeType vectorAccessBytecodeType = nullptr;
-
-    // Suggest result type of a vector function namecall
-    HostVectorOperationBytecodeType vectorNamecallBytecodeType = nullptr;
-
-    // Handle vector value field access
-    // 'sourceReg' is guaranteed to be a vector
-    // Guards should take a VM exit to 'pcpos'
-    HostVectorAccessHandler vectorAccess = nullptr;
-
-    // Handle namecall performed on a vector value
-    // 'sourceReg' (self argument) is guaranteed to be a vector
-    // All other arguments can be of any type
-    // Guards should take a VM exit to 'pcpos'
-    HostVectorNamecallHandler vectorNamecall = nullptr;
-
-    // Suggest result type of a userdata field access
-    HostUserdataOperationBytecodeType userdataAccessBytecodeType = nullptr;
-
-    // Suggest result type of a metamethod call
-    HostUserdataMetamethodBytecodeType userdataMetamethodBytecodeType = nullptr;
-
-    // Suggest result type of a userdata namecall
-    HostUserdataOperationBytecodeType userdataNamecallBytecodeType = nullptr;
-
-    // Handle userdata value field access
-    // 'sourceReg' is guaranteed to be a userdata, but tag has to be checked
-    // Write to 'resultReg' might invalidate 'sourceReg'
-    // Guards should take a VM exit to 'pcpos'
-    HostUserdataAccessHandler userdataAccess = nullptr;
-
-    // Handle metamethod operation on a userdata value
-    // 'lhs' and 'rhs' operands can be VM registers of constants
-    // Operand types have to be checked and userdata operand tags have to be checked
-    // Write to 'resultReg' might invalidate source operands
-    // Guards should take a VM exit to 'pcpos'
-    HostUserdataMetamethodHandler userdataMetamethod = nullptr;
-
-    // Handle namecall performed on a userdata value
-    // 'sourceReg' (self argument) is guaranteed to be a userdata, but tag has to be checked
-    // All other arguments can be of any type
-    // Guards should take a VM exit to 'pcpos'
-    HostUserdataNamecallHandler userdataNamecall = nullptr;
-};
-
-struct CompilationOptions
-{
-    unsigned int flags = 0;
-    HostIrHooks hooks;
-
-    // null-terminated array of userdata types names that might have custom lowering
-    const char* const* userdataTypes = nullptr;
-};
-
 struct CompilationStats
 {
     size_t bytecodeSizeBytes = 0;
@@ -184,8 +73,6 @@ struct CompilationStats
     uint32_t functionsBound = 0;
 };
 
-using AllocationCallback = void(void* context, void* oldPointer, size_t oldSize, void* newPointer, size_t newSize);
-
 bool isSupported();
 
 class SharedCodeGenContext;
@@ -249,153 +136,6 @@ CompilationResult compile(const ModuleId& moduleId, lua_State* L, int idx, unsig
 CompilationResult compile(lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats = nullptr);
 CompilationResult compile(const ModuleId& moduleId, lua_State* L, int idx, const CompilationOptions& options, CompilationStats* stats = nullptr);
 
-using AnnotatorFn = void (*)(void* context, std::string& result, int fid, int instpos);
-
-// Output "#" before IR blocks and instructions
-enum class IncludeIrPrefix
-{
-    No,
-    Yes
-};
-
-// Output user count and last use information of blocks and instructions
-enum class IncludeUseInfo
-{
-    No,
-    Yes
-};
-
-// Output CFG informations like block predecessors, successors and etc
-enum class IncludeCfgInfo
-{
-    No,
-    Yes
-};
-
-// Output VM register live in/out information for blocks
-enum class IncludeRegFlowInfo
-{
-    No,
-    Yes
-};
-
-struct AssemblyOptions
-{
-    enum Target
-    {
-        Host,
-        A64,
-        A64_NoFeatures,
-        X64_Windows,
-        X64_SystemV,
-    };
-
-    Target target = Host;
-
-    CompilationOptions compilationOptions;
-
-    bool outputBinary = false;
-
-    bool includeAssembly = false;
-    bool includeIr = false;
-    bool includeOutlinedCode = false;
-    bool includeIrTypes = false;
-
-    IncludeIrPrefix includeIrPrefix = IncludeIrPrefix::Yes;
-    IncludeUseInfo includeUseInfo = IncludeUseInfo::Yes;
-    IncludeCfgInfo includeCfgInfo = IncludeCfgInfo::Yes;
-    IncludeRegFlowInfo includeRegFlowInfo = IncludeRegFlowInfo::Yes;
-
-    // Optional annotator function can be provided to describe each instruction, it takes function id and sequential instruction id
-    AnnotatorFn annotator = nullptr;
-    void* annotatorContext = nullptr;
-};
-
-struct BlockLinearizationStats
-{
-    unsigned int constPropInstructionCount = 0;
-    double timeSeconds = 0.0;
-
-    BlockLinearizationStats& operator+=(const BlockLinearizationStats& that)
-    {
-        this->constPropInstructionCount += that.constPropInstructionCount;
-        this->timeSeconds += that.timeSeconds;
-
-        return *this;
-    }
-
-    BlockLinearizationStats operator+(const BlockLinearizationStats& other) const
-    {
-        BlockLinearizationStats result(*this);
-        result += other;
-        return result;
-    }
-};
-
-enum FunctionStatsFlags
-{
-    // Enable stats collection per function
-    FunctionStats_Enable = 1 << 0,
-    // Compute function bytecode summary
-    FunctionStats_BytecodeSummary = 1 << 1,
-};
-
-struct FunctionStats
-{
-    std::string name;
-    int line = -1;
-    unsigned bcodeCount = 0;
-    unsigned irCount = 0;
-    unsigned asmCount = 0;
-    unsigned asmSize = 0;
-    std::vector<std::vector<unsigned>> bytecodeSummary;
-};
-
-struct LoweringStats
-{
-    unsigned totalFunctions = 0;
-    unsigned skippedFunctions = 0;
-    int spillsToSlot = 0;
-    int spillsToRestore = 0;
-    unsigned maxSpillSlotsUsed = 0;
-    unsigned blocksPreOpt = 0;
-    unsigned blocksPostOpt = 0;
-    unsigned maxBlockInstructions = 0;
-
-    int regAllocErrors = 0;
-    int loweringErrors = 0;
-
-    BlockLinearizationStats blockLinearizationStats;
-
-    unsigned functionStatsFlags = 0;
-    std::vector<FunctionStats> functions;
-
-    LoweringStats operator+(const LoweringStats& other) const
-    {
-        LoweringStats result(*this);
-        result += other;
-        return result;
-    }
-
-    LoweringStats& operator+=(const LoweringStats& that)
-    {
-        this->totalFunctions += that.totalFunctions;
-        this->skippedFunctions += that.skippedFunctions;
-        this->spillsToSlot += that.spillsToSlot;
-        this->spillsToRestore += that.spillsToRestore;
-        this->maxSpillSlotsUsed = std::max(this->maxSpillSlotsUsed, that.maxSpillSlotsUsed);
-        this->blocksPreOpt += that.blocksPreOpt;
-        this->blocksPostOpt += that.blocksPostOpt;
-        this->maxBlockInstructions = std::max(this->maxBlockInstructions, that.maxBlockInstructions);
-        this->regAllocErrors += that.regAllocErrors;
-        this->loweringErrors += that.loweringErrors;
-        this->blockLinearizationStats += that.blockLinearizationStats;
-        if (this->functionStatsFlags & FunctionStats_Enable)
-            this->functions.insert(this->functions.end(), that.functions.begin(), that.functions.end());
-        return *this;
-    }
-};
-
 // Generates assembly for target function and all inner functions
 std::string getAssembly(lua_State* L, int idx, AssemblyOptions options = {}, LoweringStats* stats = nullptr);
 

CodeGen/include/Luau/CodeGenCommon.h

@@ -10,3 +10,9 @@
 #else
 #define CODEGEN_ASSERT(expr) (void)sizeof(!!(expr))
 #endif
+
+#if defined(__x86_64__) || defined(_M_X64)
+#define CODEGEN_TARGET_X64
+#elif defined(__aarch64__) || defined(_M_ARM64)
+#define CODEGEN_TARGET_A64
+#endif

CodeGen/include/Luau/CodeGenOptions.h

@@ -0,0 +1,188 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#pragma once
+
+#include <string>
+
+#include <stddef.h>
+#include <stdint.h>
+
+namespace Luau
+{
+namespace CodeGen
+{
+
+enum CodeGenFlags
+{
+    // Only run native codegen for modules that have been marked with --!native
+    CodeGen_OnlyNativeModules = 1 << 0,
+    // Run native codegen for functions that the compiler considers not profitable
+    CodeGen_ColdFunctions = 1 << 1,
+};
+
+using AllocationCallback = void(void* context, void* oldPointer, size_t oldSize, void* newPointer, size_t newSize);
+
+struct IrBuilder;
+struct IrOp;
+
+using HostVectorOperationBytecodeType = uint8_t (*)(const char* member, size_t memberLength);
+using HostVectorAccessHandler = bool (*)(IrBuilder& builder, const char* member, size_t memberLength, int resultReg, int sourceReg, int pcpos);
+using HostVectorNamecallHandler =
+    bool (*)(IrBuilder& builder, const char* member, size_t memberLength, int argResReg, int sourceReg, int params, int results, int pcpos);
+
+enum class HostMetamethod
+{
+    Add,
+    Sub,
+    Mul,
+    Div,
+    Idiv,
+    Mod,
+    Pow,
+    Minus,
+    Equal,
+    LessThan,
+    LessEqual,
+    Length,
+    Concat,
+};
+
+using HostUserdataOperationBytecodeType = uint8_t (*)(uint8_t type, const char* member, size_t memberLength);
+using HostUserdataMetamethodBytecodeType = uint8_t (*)(uint8_t lhsTy, uint8_t rhsTy, HostMetamethod method);
+using HostUserdataAccessHandler =
+    bool (*)(IrBuilder& builder, uint8_t type, const char* member, size_t memberLength, int resultReg, int sourceReg, int pcpos);
+using HostUserdataMetamethodHandler =
+    bool (*)(IrBuilder& builder, uint8_t lhsTy, uint8_t rhsTy, int resultReg, IrOp lhs, IrOp rhs, HostMetamethod method, int pcpos);
+using HostUserdataNamecallHandler = bool (*)(
+    IrBuilder& builder,
+    uint8_t type,
+    const char* member,
+    size_t memberLength,
+    int argResReg,
+    int sourceReg,
+    int params,
+    int results,
+    int pcpos
+);
+
+struct HostIrHooks
+{
+    // Suggest result type of a vector field access
+    HostVectorOperationBytecodeType vectorAccessBytecodeType = nullptr;
+
+    // Suggest result type of a vector function namecall
+    HostVectorOperationBytecodeType vectorNamecallBytecodeType = nullptr;
+
+    // Handle vector value field access
+    // 'sourceReg' is guaranteed to be a vector
+    // Guards should take a VM exit to 'pcpos'
+    HostVectorAccessHandler vectorAccess = nullptr;
+
+    // Handle namecall performed on a vector value
+    // 'sourceReg' (self argument) is guaranteed to be a vector
+    // All other arguments can be of any type
+    // Guards should take a VM exit to 'pcpos'
+    HostVectorNamecallHandler vectorNamecall = nullptr;
+
+    // Suggest result type of a userdata field access
+    HostUserdataOperationBytecodeType userdataAccessBytecodeType = nullptr;
+
+    // Suggest result type of a metamethod call
+    HostUserdataMetamethodBytecodeType userdataMetamethodBytecodeType = nullptr;
+
+    // Suggest result type of a userdata namecall
+    HostUserdataOperationBytecodeType userdataNamecallBytecodeType = nullptr;
+
+    // Handle userdata value field access
+    // 'sourceReg' is guaranteed to be a userdata, but tag has to be checked
+    // Write to 'resultReg' might invalidate 'sourceReg'
+    // Guards should take a VM exit to 'pcpos'
+    HostUserdataAccessHandler userdataAccess = nullptr;
+
+    // Handle metamethod operation on a userdata value
+    // 'lhs' and 'rhs' operands can be VM registers of constants
+    // Operand types have to be checked and userdata operand tags have to be checked
+    // Write to 'resultReg' might invalidate source operands
+    // Guards should take a VM exit to 'pcpos'
+    HostUserdataMetamethodHandler userdataMetamethod = nullptr;
+
+    // Handle namecall performed on a userdata value
+    // 'sourceReg' (self argument) is guaranteed to be a userdata, but tag has to be checked
+    // All other arguments can be of any type
+    // Guards should take a VM exit to 'pcpos'
+    HostUserdataNamecallHandler userdataNamecall = nullptr;
+};
+
+struct CompilationOptions
+{
+    unsigned int flags = 0;
+    HostIrHooks hooks;
+
+    // null-terminated array of userdata types names that might have custom lowering
+    const char* const* userdataTypes = nullptr;
+};
+
+
+using AnnotatorFn = void (*)(void* context, std::string& result, int fid, int instpos);
+
+// Output "#" before IR blocks and instructions
+enum class IncludeIrPrefix
+{
+    No,
+    Yes
+};
+
+// Output user count and last use information of blocks and instructions
+enum class IncludeUseInfo
+{
+    No,
+    Yes
+};
+
+// Output CFG informations like block predecessors, successors and etc
+enum class IncludeCfgInfo
+{
+    No,
+    Yes
+};
+
+// Output VM register live in/out information for blocks
+enum class IncludeRegFlowInfo
+{
+    No,
+    Yes
+};
+
+struct AssemblyOptions
+{
+    enum Target
+    {
+        Host,
+        A64,
+        A64_NoFeatures,
+        X64_Windows,
+        X64_SystemV,
+    };
+
+    Target target = Host;
+
+    CompilationOptions compilationOptions;
+
+    bool outputBinary = false;
+
+    bool includeAssembly = false;
+    bool includeIr = false;
+    bool includeOutlinedCode = false;
+    bool includeIrTypes = false;
+
+    IncludeIrPrefix includeIrPrefix = IncludeIrPrefix::Yes;
+    IncludeUseInfo includeUseInfo = IncludeUseInfo::Yes;
+    IncludeCfgInfo includeCfgInfo = IncludeCfgInfo::Yes;
+    IncludeRegFlowInfo includeRegFlowInfo = IncludeRegFlowInfo::Yes;
+
+    // Optional annotator function can be provided to describe each instruction, it takes function id and sequential instruction id
+    AnnotatorFn annotator = nullptr;
+    void* annotatorContext = nullptr;
+};
+
+} // namespace CodeGen
+} // namespace Luau

CodeGen/include/Luau/IrData.h

@@ -20,6 +20,8 @@ namespace Luau
 namespace CodeGen
 {
 
+struct LoweringStats;
+
 // IR extensions to LuauBuiltinFunction enum (these only exist inside IR, and start from 256 to avoid collisions)
 enum
 {
@@ -67,18 +69,18 @@ enum class IrCmd : uint8_t
     LOAD_ENV,
 
     // Get pointer (TValue) to table array at index
-    // A: pointer (Table)
+    // A: pointer (LuaTable)
     // B: int
     GET_ARR_ADDR,
 
     // Get pointer (LuaNode) to table node element at the active cached slot index
-    // A: pointer (Table)
+    // A: pointer (LuaTable)
     // B: unsigned int (pcpos)
     // C: Kn
     GET_SLOT_NODE_ADDR,
 
     // Get pointer (LuaNode) to table node element at the main position of the specified key hash
-    // A: pointer (Table)
+    // A: pointer (LuaTable)
     // B: unsigned int (hash)
     GET_HASH_NODE_ADDR,
 
@@ -185,6 +187,11 @@ enum class IrCmd : uint8_t
     // A: double
     SIGN_NUM,
 
+    // Select B if C == D, otherwise select A
+    // A, B: double (endpoints)
+    // C, D: double (condition arguments)
+    SELECT_NUM,
+
     // Add/Sub/Mul/Div/Idiv two vectors
     // A, B: TValue
     ADD_VEC,
@@ -268,7 +275,7 @@ enum class IrCmd : uint8_t
     JUMP_SLOT_MATCH,
 
     // Get table length
-    // A: pointer (Table)
+    // A: pointer (LuaTable)
     TABLE_LEN,
 
     // Get string length
@@ -281,11 +288,11 @@ enum class IrCmd : uint8_t
     NEW_TABLE,
 
     // Duplicate a table
-    // A: pointer (Table)
+    // A: pointer (LuaTable)
     DUP_TABLE,
 
     // Insert an integer key into a table and return the pointer to inserted value (TValue)
-    // A: pointer (Table)
+    // A: pointer (LuaTable)
     // B: int (key)
     TABLE_SETNUM,
 
@@ -425,13 +432,13 @@ enum class IrCmd : uint8_t
     CHECK_TRUTHY,
 
     // Guard against readonly table
-    // A: pointer (Table)
+    // A: pointer (LuaTable)
     // B: block/vmexit/undef
     // When undef is specified instead of a block, execution is aborted on check failure
     CHECK_READONLY,
 
     // Guard against table having a metatable
-    // A: pointer (Table)
+    // A: pointer (LuaTable)
     // B: block/vmexit/undef
     // When undef is specified instead of a block, execution is aborted on check failure
     CHECK_NO_METATABLE,
@@ -442,7 +449,7 @@ enum class IrCmd : uint8_t
     CHECK_SAFE_ENV,
 
     // Guard against index overflowing the table array size
-    // A: pointer (Table)
+    // A: pointer (LuaTable)
     // B: int (index)
     // C: block/vmexit/undef
     // When undef is specified instead of a block, execution is aborted on check failure
@@ -498,11 +505,11 @@ enum class IrCmd : uint8_t
     BARRIER_OBJ,
 
     // Handle GC write barrier (backwards) for a write into a table
-    // A: pointer (Table)
+    // A: pointer (LuaTable)
     BARRIER_TABLE_BACK,
 
     // Handle GC write barrier (forward) for a write into a table
-    // A: pointer (Table)
+    // A: pointer (LuaTable)
     // B: Rn (TValue that was written to the object)
     // C: tag/undef (tag of the value that was written)
     BARRIER_TABLE_FORWARD,
@@ -1044,6 +1051,8 @@ struct IrFunction
 
     CfgInfo cfg;
 
+    LoweringStats* stats = nullptr;
+
     IrBlock& blockOp(IrOp op)
     {
         CODEGEN_ASSERT(op.kind == IrOpKind::Block);

CodeGen/include/Luau/IrDump.h

@@ -2,11 +2,13 @@
 #pragma once
 
 #include "Luau/IrData.h"
-#include "Luau/CodeGen.h"
+#include "Luau/CodeGenOptions.h"
 
 #include <string>
 #include <vector>
 
+struct Proto;
+
 namespace Luau
 {
 namespace CodeGen
@@ -23,6 +25,7 @@ struct IrToStringContext
     const std::vector<IrBlock>& blocks;
     const std::vector<IrConst>& constants;
     const CfgInfo& cfg;
+    Proto* proto = nullptr;
 };
 
 void toString(IrToStringContext& ctx, const IrInst& inst, uint32_t index);

CodeGen/include/Luau/IrUtils.h

@@ -174,6 +174,7 @@ inline bool hasResult(IrCmd cmd)
     case IrCmd::SQRT_NUM:
     case IrCmd::ABS_NUM:
     case IrCmd::SIGN_NUM:
+    case IrCmd::SELECT_NUM:
     case IrCmd::ADD_VEC:
     case IrCmd::SUB_VEC:
     case IrCmd::MUL_VEC: