Merge branch 'main' into prototyping-numbers

.github/workflows/build.yml

@@ -9,12 +9,14 @@ on:
       - 'papers/**'
       - 'rfcs/**'
       - '*.md'
+      - 'prototyping/**'
   pull_request:
     paths-ignore:
       - 'docs/**'
       - 'papers/**'
       - 'rfcs/**'
       - '*.md'
+      - 'prototyping/**'
 
 jobs:
   unix:

.github/workflows/prototyping.yml

@@ -8,12 +8,18 @@ on:
     paths:
       - '.github/workflows/**'
       - 'prototyping/**'
-      - 'Analysis/src/JsonEncoder.cpp'
+      - 'Analysis/**'
+      - 'Ast/**'
+      - 'CLI/Ast.cpp'
+      - 'CLI/FileUtils.*'
   pull_request:
     paths:
       - '.github/workflows/**'
       - 'prototyping/**'
-      - 'Analysis/src/JsonEncoder.cpp'
+      - 'Analysis/**'
+      - 'Ast/**'
+      - 'CLI/Ast.cpp'
+      - 'CLI/FileUtils.*'
 
 jobs:
   linux:
@@ -28,6 +34,11 @@ jobs:
       with:
         path: ~/.cabal/store
         key: prototyping-${{ runner.os }}-${{ matrix.agda }}
+    - uses: actions/cache@v2
+      id: luau-ast-cache
+      with:
+        path: ./build
+        key: prototyping-${{ runner.os }}-${{ hashFiles('Ast/**', 'Analysis/**', 'CLI/Ast.cpp', 'CLI/FileUtils.*')}}
     - name: install cabal
       run: sudo apt-get install -y cabal-install
     - name: cabal update
@@ -37,26 +48,35 @@ jobs:
       working-directory: prototyping
       run: |
         cabal install Agda-${{ matrix.agda }}
-        cabal install --lib scientific --package-env .
+        cabal install --lib scientific vector aeson --package-env .
-        cabal install --lib vector --package-env .
+    - name: check targets
-        cabal install --lib aeson --package-env .
-    - name: check examples
       working-directory: prototyping
-      run: ~/.cabal/bin/agda Examples.agda
+      run: |
+        ~/.cabal/bin/agda Examples.agda
+        ~/.cabal/bin/agda Properties.agda
     - name: build executables
       working-directory: prototyping
       run: |
         ~/.cabal/bin/agda --compile PrettyPrinter.agda
         ~/.cabal/bin/agda --compile Interpreter.agda
     - name: cmake configure
-      run: cmake .
+      if: steps.luau-ast-cache.outputs.cache-hit != 'true'
+      run: |
+        mkdir -p build
+        cd build
+        cmake build ../
     - name: cmake build luau-ast
-      run: cmake --build . --target Luau.Ast.CLI
+      if: steps.luau-ast-cache.outputs.cache-hit != 'true'
-    - name: run smoketest
+      run: |
+        cmake --build ./build --target Luau.Ast.CLI
+    - name: run tests
       working-directory: prototyping
       run: |
-        ../luau-ast Examples/SmokeTest.lua | ./PrettyPrinter > Examples/SmokeTestOutput.lua
+        mkdir test-failures
-        ../luau-ast Examples/SmokeTest.lua | ./Interpreter
+        python tests.py -l ../build/luau-ast --write-diff-failures --diff-failure-location test-failures/
-    - name: diff smoketest
+    - uses: actions/upload-artifact@v2
-      working-directory: prototyping
+      if: failure()
-      run: diff Examples/SmokeTest.lua Examples/SmokeTestOutput.lua
+      with:
+        name: test failures
+        path: prototyping/test-failures
+        retention-days: 5

.github/workflows/release.yml

@@ -9,6 +9,7 @@ on:
       - 'papers/**'
       - 'rfcs/**'
       - '*.md'
+      - 'prototyping/**'
 
 jobs:
   build:

Analysis/include/Luau/Documentation.h

@@ -21,6 +21,7 @@ struct BasicDocumentation
 {
     std::string documentation;
     std::string learnMoreLink;
+    std::string codeSample;
 };
 
 struct FunctionParameterDocumentation
@@ -37,6 +38,7 @@ struct FunctionDocumentation
     std::vector<FunctionParameterDocumentation> parameters;
     std::vector<DocumentationSymbol> returns;
     std::string learnMoreLink;
+    std::string codeSample;
 };
 
 struct OverloadedFunctionDocumentation
@@ -52,6 +54,7 @@ struct TableDocumentation
     std::string documentation;
     Luau::DenseHashMap<std::string, DocumentationSymbol> keys;
     std::string learnMoreLink;
+    std::string codeSample;
 };
 
 using DocumentationDatabase = Luau::DenseHashMap<DocumentationSymbol, Documentation>;

Analysis/include/Luau/Frontend.h

@@ -24,6 +24,7 @@ struct TypeChecker;
 struct FileResolver;
 struct ModuleResolver;
 struct ParseResult;
+struct HotComment;
 
 struct LoadDefinitionFileResult
 {
@@ -35,7 +36,7 @@ struct LoadDefinitionFileResult
 LoadDefinitionFileResult loadDefinitionFile(
     TypeChecker& typeChecker, ScopePtr targetScope, std::string_view definition, const std::string& packageName);
 
-std::optional<Mode> parseMode(const std::vector<std::string>& hotcomments);
+std::optional<Mode> parseMode(const std::vector<HotComment>& hotcomments);
 
 std::vector<std::string_view> parsePathExpr(const AstExpr& pathExpr);
 

Analysis/include/Luau/Linter.h

@@ -14,6 +14,7 @@ class AstStat;
 class AstNameTable;
 struct TypeChecker;
 struct Module;
+struct HotComment;
 
 using ScopePtr = std::shared_ptr<struct Scope>;
 
@@ -50,6 +51,7 @@ struct LintWarning
         Code_TableOperations = 23,
         Code_DuplicateCondition = 24,
         Code_MisleadingAndOr = 25,
+        Code_CommentDirective = 26,
 
         Code__Count
     };
@@ -60,7 +62,7 @@ struct LintWarning
 
     static const char* getName(Code code);
     static Code parseName(const char* name);
-    static uint64_t parseMask(const std::vector<std::string>& hotcomments);
+    static uint64_t parseMask(const std::vector<HotComment>& hotcomments);
 };
 
 struct LintResult
@@ -90,7 +92,8 @@ struct LintOptions
     void setDefaults();
 };
 
-std::vector<LintWarning> lint(AstStat* root, const AstNameTable& names, const ScopePtr& env, const Module* module, const LintOptions& options);
+std::vector<LintWarning> lint(AstStat* root, const AstNameTable& names, const ScopePtr& env, const Module* module,
+    const std::vector<HotComment>& hotcomments, const LintOptions& options);
 
 std::vector<AstName> getDeprecatedGlobals(const AstNameTable& names);
 

Analysis/include/Luau/Module.h

@@ -6,7 +6,7 @@
 #include "Luau/TypedAllocator.h"
 #include "Luau/ParseOptions.h"
 #include "Luau/Error.h"
-#include "Luau/Parser.h"
+#include "Luau/ParseResult.h"
 
 #include <memory>
 #include <vector>
@@ -37,8 +37,8 @@ struct SourceModule
 
     AstStatBlock* root = nullptr;
     std::optional<Mode> mode;
-    uint64_t ignoreLints = 0;
 
+    std::vector<HotComment> hotcomments;
     std::vector<Comment> commentLocations;
 
     SourceModule()

Analysis/include/Luau/Quantify.h

@@ -6,9 +6,6 @@
 namespace Luau
 {
 
-struct Module;
+void quantify(TypeId ty, TypeLevel level);
-using ModulePtr = std::shared_ptr<Module>;
-
-void quantify(ModulePtr module, TypeId ty, TypeLevel level);
 
 } // namespace Luau

Analysis/include/Luau/Substitution.h

@@ -101,9 +101,6 @@ struct Tarjan
     // This is hot code, so we optimize recursion to a stack.
     TarjanResult loop();
 
-    // Clear the state
-    void clear();
-
     // Find or create the index for a vertex.
     // Return a boolean which is `true` if it's a freshly created index.
     std::pair<int, bool> indexify(TypeId ty);
@@ -166,7 +163,17 @@ struct FindDirty : Tarjan
 // and replaces them with clean ones.
 struct Substitution : FindDirty
 {
-    ModulePtr currentModule;
+protected:
+    Substitution(const TxnLog* log_, TypeArena* arena)
+        : arena(arena)
+    {
+        log = log_;
+        LUAU_ASSERT(log);
+        LUAU_ASSERT(arena);
+    }
+
+public:
+    TypeArena* arena;
     DenseHashMap<TypeId, TypeId> newTypes{nullptr};
     DenseHashMap<TypePackId, TypePackId> newPacks{nullptr};
 
@@ -192,12 +199,13 @@ struct Substitution : FindDirty
     template<typename T>
     TypeId addType(const T& tv)
     {
-        return currentModule->internalTypes.addType(tv);
+        return arena->addType(tv);
     }
+
     template<typename T>
     TypePackId addTypePack(const T& tp)
     {
-        return currentModule->internalTypes.addTypePack(TypePackVar{tp});
+        return arena->addTypePack(TypePackVar{tp});
     }
 };
 

Analysis/include/Luau/TypeInfer.h

@@ -5,7 +5,6 @@
 #include "Luau/Error.h"
 #include "Luau/Module.h"
 #include "Luau/Symbol.h"
-#include "Luau/Parser.h"
 #include "Luau/Substitution.h"
 #include "Luau/TxnLog.h"
 #include "Luau/TypePack.h"
@@ -37,6 +36,15 @@ struct Unifier;
 // A substitution which replaces generic types in a given set by free types.
 struct ReplaceGenerics : Substitution
 {
+    ReplaceGenerics(
+        const TxnLog* log, TypeArena* arena, TypeLevel level, const std::vector<TypeId>& generics, const std::vector<TypePackId>& genericPacks)
+        : Substitution(log, arena)
+        , level(level)
+        , generics(generics)
+        , genericPacks(genericPacks)
+    {
+    }
+
     TypeLevel level;
     std::vector<TypeId> generics;
     std::vector<TypePackId> genericPacks;
@@ -50,8 +58,13 @@ struct ReplaceGenerics : Substitution
 // A substitution which replaces generic functions by monomorphic functions
 struct Instantiation : Substitution
 {
+    Instantiation(const TxnLog* log, TypeArena* arena, TypeLevel level)
+        : Substitution(log, arena)
+        , level(level)
+    {
+    }
+
     TypeLevel level;
-    ReplaceGenerics replaceGenerics;
     bool ignoreChildren(TypeId ty) override;
     bool isDirty(TypeId ty) override;
     bool isDirty(TypePackId tp) override;
@@ -62,6 +75,12 @@ struct Instantiation : Substitution
 // A substitution which replaces free types by generic types.
 struct Quantification : Substitution
 {
+    Quantification(TypeArena* arena, TypeLevel level)
+        : Substitution(TxnLog::empty(), arena)
+        , level(level)
+    {
+    }
+
     TypeLevel level;
     std::vector<TypeId> generics;
     std::vector<TypePackId> genericPacks;
@@ -74,6 +93,13 @@ struct Quantification : Substitution
 // A substitution which replaces free types by any
 struct Anyification : Substitution
 {
+    Anyification(TypeArena* arena, TypeId anyType, TypePackId anyTypePack)
+        : Substitution(TxnLog::empty(), arena)
+        , anyType(anyType)
+        , anyTypePack(anyTypePack)
+    {
+    }
+
     TypeId anyType;
     TypePackId anyTypePack;
     bool isDirty(TypeId ty) override;
@@ -85,6 +111,13 @@ struct Anyification : Substitution
 // A substitution which replaces the type parameters of a type function by arguments
 struct ApplyTypeFunction : Substitution
 {
+    ApplyTypeFunction(TypeArena* arena, TypeLevel level)
+        : Substitution(TxnLog::empty(), arena)
+        , level(level)
+        , encounteredForwardedType(false)
+    {
+    }
+
     TypeLevel level;
     bool encounteredForwardedType;
     std::unordered_map<TypeId, TypeId> typeArguments;
@@ -351,8 +384,7 @@ private:
 
     // Note: `scope` must be a fresh scope.
     GenericTypeDefinitions createGenericTypes(const ScopePtr& scope, std::optional<TypeLevel> levelOpt, const AstNode& node,
-        const AstArray<AstGenericType>& genericNames, const AstArray<AstGenericTypePack>& genericPackNames,
+        const AstArray<AstGenericType>& genericNames, const AstArray<AstGenericTypePack>& genericPackNames, bool useCache = false);
-        bool useCache = false);
 
 public:
     ErrorVec resolve(const PredicateVec& predicates, const ScopePtr& scope, bool sense);
@@ -392,11 +424,6 @@ public:
     ModulePtr currentModule;
     ModuleName currentModuleName;
 
-    Instantiation instantiation;
-    Quantification quantification;
-    Anyification anyification;
-    ApplyTypeFunction applyTypeFunction;
-
     std::function<void(const ModuleName&, const ScopePtr&)> prepareModuleScope;
     InternalErrorReporter* iceHandler;
 

Analysis/src/Autocomplete.cpp

@@ -7,6 +7,7 @@
 #include "Luau/ToString.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypePack.h"
+#include "Luau/Parser.h" // TODO: only needed for autocompleteSource which is deprecated
 
 #include <algorithm>
 #include <unordered_set>
@@ -14,9 +15,9 @@
 
 LUAU_FASTFLAG(LuauUseCommittingTxnLog)
 LUAU_FASTFLAGVARIABLE(LuauAutocompleteAvoidMutation, false);
-LUAU_FASTFLAGVARIABLE(LuauCompleteBrokenStringParams, false);
 LUAU_FASTFLAGVARIABLE(LuauMissingFollowACMetatables, false);
 LUAU_FASTFLAGVARIABLE(PreferToCallFunctionsForIntersects, false);
+LUAU_FASTFLAGVARIABLE(LuauIfElseExprFixCompletionIssue, false);
 
 static const std::unordered_set<std::string> kStatementStartingKeywords = {
     "while", "if", "local", "repeat", "function", "do", "for", "return", "break", "continue", "type", "export"};
@@ -380,7 +381,7 @@ static void autocompleteProps(const Module& module, TypeArena* typeArena, TypeId
         {
             // We are walking up the class hierarchy, so if we encounter a property that we have
             // already populated, it takes precedence over the property we found just now.
-            if (result.count(name) == 0 && name != Parser::errorName)
+            if (result.count(name) == 0 && name != kParseNameError)
             {
                 Luau::TypeId type = Luau::follow(prop.type);
                 TypeCorrectKind typeCorrect = indexType == PropIndexType::Key ? TypeCorrectKind::Correct
@@ -948,9 +949,12 @@ AutocompleteEntryMap autocompleteTypeNames(const Module& module, Position positi
             }
         }
 
-        for (size_t i = 0; i < node->returnAnnotation.types.size; i++)
+        if (!node->returnAnnotation)
+            return result;
+
+        for (size_t i = 0; i < node->returnAnnotation->types.size; i++)
         {
-            AstType* ret = node->returnAnnotation.types.data[i];
+            AstType* ret = node->returnAnnotation->types.data[i];
 
             if (ret->location.containsClosed(position))
             {
@@ -965,7 +969,7 @@ AutocompleteEntryMap autocompleteTypeNames(const Module& module, Position positi
             }
         }
 
-        if (AstTypePack* retTp = node->returnAnnotation.tailType)
+        if (AstTypePack* retTp = node->returnAnnotation->tailType)
         {
             if (auto variadic = retTp->as<AstTypePackVariadic>())
             {
@@ -1136,7 +1140,7 @@ static AutocompleteEntryMap autocompleteStatement(
         AstNode* parent = ancestry.rbegin()[1];
         if (AstStatIf* statIf = parent->as<AstStatIf>())
         {
-            if (!statIf->elsebody || (statIf->hasElse && statIf->elseLocation.containsClosed(position)))
+            if (!statIf->elsebody || (statIf->elseLocation && statIf->elseLocation->containsClosed(position)))
             {
                 result.emplace("else", AutocompleteEntry{AutocompleteEntryKind::Keyword});
                 result.emplace("elseif", AutocompleteEntry{AutocompleteEntryKind::Keyword});
@@ -1164,8 +1168,7 @@ static AutocompleteEntryMap autocompleteStatement(
     return result;
 }
 
-// Returns true if completions were generated (completions will be inserted into 'outResult')
+// Returns true iff `node` was handled by this function (completions, if any, are returned in `outResult`)
-// Returns false if no completions were generated
 static bool autocompleteIfElseExpression(
     const AstNode* node, const std::vector<AstNode*>& ancestry, const Position& position, AutocompleteEntryMap& outResult)
 {
@@ -1173,6 +1176,13 @@ static bool autocompleteIfElseExpression(
     if (!parent)
         return false;
 
+    if (FFlag::LuauIfElseExprFixCompletionIssue && node->is<AstExprIfElse>())
+    {
+        // Don't try to complete when the current node is an if-else expression (i.e. only try to complete when the node is a child of an if-else
+        // expression.
+        return true;
+    }
+
     AstExprIfElse* ifElseExpr = parent->as<AstExprIfElse>();
     if (!ifElseExpr || ifElseExpr->condition->location.containsClosed(position))
     {
@@ -1310,7 +1320,7 @@ static std::optional<AutocompleteEntryMap> autocompleteStringParams(const Source
         return std::nullopt;
     }
 
-    if (!nodes.back()->is<AstExprConstantString>() && (!FFlag::LuauCompleteBrokenStringParams || !nodes.back()->is<AstExprError>()))
+    if (!nodes.back()->is<AstExprConstantString>() && !nodes.back()->is<AstExprError>())
     {
         return std::nullopt;
     }
@@ -1408,8 +1418,8 @@ static AutocompleteResult autocomplete(const SourceModule& sourceModule, const M
     }
     else if (auto typeReference = node->as<AstTypeReference>())
     {
-        if (typeReference->hasPrefix)
+        if (typeReference->prefix)
-            return {autocompleteModuleTypes(*module, position, typeReference->prefix.value), finder.ancestry};
+            return {autocompleteModuleTypes(*module, position, typeReference->prefix->value), finder.ancestry};
         else
             return {autocompleteTypeNames(*module, position, finder.ancestry), finder.ancestry};
     }
@@ -1419,9 +1429,9 @@ static AutocompleteResult autocomplete(const SourceModule& sourceModule, const M
     }
     else if (AstStatLocal* statLocal = node->as<AstStatLocal>())
     {
-        if (statLocal->vars.size == 1 && (!statLocal->hasEqualsSign || position < statLocal->equalsSignLocation.begin))
+        if (statLocal->vars.size == 1 && (!statLocal->equalsSignLocation || position < statLocal->equalsSignLocation->begin))
             return {{{"function", AutocompleteEntry{AutocompleteEntryKind::Keyword}}}, finder.ancestry};
-        else if (statLocal->hasEqualsSign && position >= statLocal->equalsSignLocation.end)
+        else if (statLocal->equalsSignLocation && position >= statLocal->equalsSignLocation->end)
             return {autocompleteExpression(sourceModule, *module, typeChecker, typeArena, finder.ancestry, position), finder.ancestry};
         else
             return {};
@@ -1449,7 +1459,7 @@ static AutocompleteResult autocomplete(const SourceModule& sourceModule, const M
         if (!statForIn->hasIn || position <= statForIn->inLocation.begin)
         {
             AstLocal* lastName = statForIn->vars.data[statForIn->vars.size - 1];
-            if (lastName->name == Parser::errorName || lastName->location.containsClosed(position))
+            if (lastName->name == kParseNameError || lastName->location.containsClosed(position))
             {
                 // Here we are either working with a missing binding (as would be the case in a bare "for" keyword) or
                 // the cursor is still touching a binding name.  The user is still typing a new name, so we should not offer
@@ -1499,7 +1509,7 @@ static AutocompleteResult autocomplete(const SourceModule& sourceModule, const M
     else if (AstStatWhile* statWhile = extractStat<AstStatWhile>(finder.ancestry); statWhile && !statWhile->hasDo)
         return {{{"do", AutocompleteEntry{AutocompleteEntryKind::Keyword}}}, finder.ancestry};
 
-    else if (AstStatIf* statIf = node->as<AstStatIf>(); statIf && !statIf->hasElse)
+    else if (AstStatIf* statIf = node->as<AstStatIf>(); statIf && !statIf->elseLocation.has_value())
     {
         return {{{"else", AutocompleteEntry{AutocompleteEntryKind::Keyword}}, {"elseif", AutocompleteEntry{AutocompleteEntryKind::Keyword}}},
             finder.ancestry};
@@ -1508,11 +1518,11 @@ static AutocompleteResult autocomplete(const SourceModule& sourceModule, const M
     {
         if (statIf->condition->is<AstExprError>())
             return {autocompleteExpression(sourceModule, *module, typeChecker, typeArena, finder.ancestry, position), finder.ancestry};
-        else if (!statIf->hasThen || statIf->thenLocation.containsClosed(position))
+        else if (!statIf->thenLocation || statIf->thenLocation->containsClosed(position))
             return {{{"then", AutocompleteEntry{AutocompleteEntryKind::Keyword}}}, finder.ancestry};
     }
     else if (AstStatIf* statIf = extractStat<AstStatIf>(finder.ancestry);
-             statIf && (!statIf->hasThen || statIf->thenLocation.containsClosed(position)))
+             statIf && (!statIf->thenLocation || statIf->thenLocation->containsClosed(position)))
         return {{{"then", AutocompleteEntry{AutocompleteEntryKind::Keyword}}}, finder.ancestry};
     else if (AstStatRepeat* statRepeat = node->as<AstStatRepeat>(); statRepeat && statRepeat->condition->is<AstExprError>())
         return {autocompleteExpression(sourceModule, *module, typeChecker, typeArena, finder.ancestry, position), finder.ancestry};
@@ -1612,6 +1622,7 @@ AutocompleteResult autocomplete(Frontend& frontend, const ModuleName& moduleName
 
 OwningAutocompleteResult autocompleteSource(Frontend& frontend, std::string_view source, Position position, StringCompletionCallback callback)
 {
+    // TODO: Remove #include "Luau/Parser.h" with this function
     auto sourceModule = std::make_unique<SourceModule>();
     ParseOptions parseOptions;
     parseOptions.captureComments = true;

Analysis/src/Config.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 "Luau/Config.h"
 
-#include "Luau/Parser.h"
+#include "Luau/Lexer.h"
 #include "Luau/StringUtils.h"
 
 namespace

Analysis/src/EmbeddedBuiltinDefinitions.cpp

@@ -167,7 +167,7 @@ declare function gcinfo(): number
                 foreach: <K, V>({[K]: V}, (K, V) -> ()) -> (),
                 foreachi: <V>({V}, (number, V) -> ()) -> (),
 
-                move: <V>({V}, number, number, number, {V}?) -> (),
+                move: <V>({V}, number, number, number, {V}?) -> {V},
                 clear: <K, V>({[K]: V}) -> (),
 
                 freeze: <K, V>({[K]: V}) -> {[K]: V},

Analysis/src/Frontend.cpp

@@ -4,6 +4,7 @@
 #include "Luau/Common.h"
 #include "Luau/Config.h"
 #include "Luau/FileResolver.h"
+#include "Luau/Parser.h"
 #include "Luau/Scope.h"
 #include "Luau/StringUtils.h"
 #include "Luau/TimeTrace.h"
@@ -16,23 +17,25 @@
 #include <stdexcept>
 
 LUAU_FASTFLAG(LuauInferInNoCheckMode)
-LUAU_FASTFLAGVARIABLE(LuauTypeCheckTwice, false)
 LUAU_FASTFLAGVARIABLE(LuauKnowsTheDataModel3, false)
 
 namespace Luau
 {
 
-std::optional<Mode> parseMode(const std::vector<std::string>& hotcomments)
+std::optional<Mode> parseMode(const std::vector<HotComment>& hotcomments)
 {
-    for (const std::string& hc : hotcomments)
+    for (const HotComment& hc : hotcomments)
     {
-        if (hc == "nocheck")
+        if (!hc.header)
+            continue;
+
+        if (hc.content == "nocheck")
             return Mode::NoCheck;
 
-        if (hc == "nonstrict")
+        if (hc.content == "nonstrict")
             return Mode::Nonstrict;
 
-        if (hc == "strict")
+        if (hc.content == "strict")
             return Mode::Strict;
     }
 
@@ -607,13 +610,15 @@ std::pair<SourceModule, LintResult> Frontend::lintFragment(std::string_view sour
 
     SourceModule sourceModule = parse(ModuleName{}, source, config.parseOptions);
 
+    uint64_t ignoreLints = LintWarning::parseMask(sourceModule.hotcomments);
+
     Luau::LintOptions lintOptions = enabledLintWarnings.value_or(config.enabledLint);
-    lintOptions.warningMask &= sourceModule.ignoreLints;
+    lintOptions.warningMask &= ~ignoreLints;
 
     double timestamp = getTimestamp();
 
-    std::vector<LintWarning> warnings =
+    std::vector<LintWarning> warnings = Luau::lint(sourceModule.root, *sourceModule.names.get(), typeChecker.globalScope, nullptr,
-        Luau::lint(sourceModule.root, *sourceModule.names.get(), typeChecker.globalScope, nullptr, enabledLintWarnings.value_or(config.enabledLint));
+        sourceModule.hotcomments, enabledLintWarnings.value_or(config.enabledLint));
 
     stats.timeLint += getTimestamp() - timestamp;
 
@@ -651,8 +656,10 @@ LintResult Frontend::lint(const SourceModule& module, std::optional<Luau::LintOp
 
     const Config& config = configResolver->getConfig(module.name);
 
+    uint64_t ignoreLints = LintWarning::parseMask(module.hotcomments);
+
     LintOptions options = enabledLintWarnings.value_or(config.enabledLint);
-    options.warningMask &= ~module.ignoreLints;
+    options.warningMask &= ~ignoreLints;
 
     Mode mode = module.mode.value_or(config.mode);
     if (mode != Mode::NoCheck)
@@ -671,7 +678,7 @@ LintResult Frontend::lint(const SourceModule& module, std::optional<Luau::LintOp
 
     double timestamp = getTimestamp();
 
-    std::vector<LintWarning> warnings = Luau::lint(module.root, *module.names, environmentScope, modulePtr.get(), options);
+    std::vector<LintWarning> warnings = Luau::lint(module.root, *module.names, environmentScope, modulePtr.get(), module.hotcomments, options);
 
     stats.timeLint += getTimestamp() - timestamp;
 
@@ -839,7 +846,6 @@ SourceModule Frontend::parse(const ModuleName& name, std::string_view src, const
     {
         sourceModule.root = parseResult.root;
         sourceModule.mode = parseMode(parseResult.hotcomments);
-        sourceModule.ignoreLints = LintWarning::parseMask(parseResult.hotcomments);
     }
     else
     {
@@ -848,8 +854,13 @@ SourceModule Frontend::parse(const ModuleName& name, std::string_view src, const
     }
 
     sourceModule.name = name;
+
     if (parseOptions.captureComments)
+    {
         sourceModule.commentLocations = std::move(parseResult.commentLocations);
+        sourceModule.hotcomments = std::move(parseResult.hotcomments);
+    }
+
     return sourceModule;
 }
 

Analysis/src/JsonEncoder.cpp

@@ -158,6 +158,13 @@ struct AstJsonEncoder : public AstVisitor
     {
         writeString(str);
     }
+    void write(std::optional<AstName> name)
+    {
+        if (name)
+            write(*name);
+        else
+            writeRaw("null");
+    }
     void write(AstName name)
     {
         writeString(name.value ? name.value : "");
@@ -327,7 +334,7 @@ struct AstJsonEncoder : public AstVisitor
             if (node->self)
                 PROP(self);
             PROP(args);
-            if (node->hasReturnAnnotation)
+            if (node->returnAnnotation)
                 PROP(returnAnnotation);
             PROP(vararg);
             PROP(varargLocation);
@@ -341,6 +348,14 @@ struct AstJsonEncoder : public AstVisitor
         });
     }
 
+    void write(const std::optional<AstTypeList>& typeList)
+    {
+        if (typeList)
+            write(*typeList);
+        else
+            writeRaw("null");
+    }
+
     void write(const AstTypeList& typeList)
     {
         writeRaw("{");
@@ -544,7 +559,7 @@ struct AstJsonEncoder : public AstVisitor
             PROP(thenbody);
             if (node->elsebody)
                 PROP(elsebody);
-            PROP(hasThen);
+            write("hasThen", node->thenLocation.has_value());
             PROP(hasEnd);
         });
     }
@@ -728,7 +743,7 @@ struct AstJsonEncoder : public AstVisitor
     void write(class AstTypeReference* node)
     {
         writeNode(node, "AstTypeReference", [&]() {
-            if (node->hasPrefix)
+            if (node->prefix)
                 PROP(prefix);
             PROP(name);
             PROP(parameters);

Analysis/src/Linter.cpp

@@ -12,6 +12,8 @@
 #include <math.h>
 #include <limits.h>
 
+LUAU_FASTINTVARIABLE(LuauSuggestionDistance, 4)
+
 namespace Luau
 {
 
@@ -44,6 +46,7 @@ static const char* kWarningNames[] = {
     "TableOperations",
     "DuplicateCondition",
     "MisleadingAndOr",
+    "CommentDirective",
 };
 // clang-format on
 
@@ -732,13 +735,13 @@ private:
 
     bool visit(AstTypeReference* node) override
     {
-        if (!node->hasPrefix)
+        if (!node->prefix)
             return true;
 
-        if (!imports.contains(node->prefix))
+        if (!imports.contains(*node->prefix))
             return true;
 
-        AstLocal* astLocal = imports[node->prefix];
+        AstLocal* astLocal = imports[*node->prefix];
         Local& local = locals[astLocal];
         LUAU_ASSERT(local.import);
         local.used = true;
@@ -2527,13 +2530,108 @@ static void fillBuiltinGlobals(LintContext& context, const AstNameTable& names,
     }
 }
 
+static const char* fuzzyMatch(std::string_view str, const char** array, size_t size)
+{
+    if (FInt::LuauSuggestionDistance == 0)
+        return nullptr;
+
+    size_t bestDistance = FInt::LuauSuggestionDistance;
+    size_t bestMatch = size;
+
+    for (size_t i = 0; i < size; ++i)
+    {
+        size_t ed = editDistance(str, array[i]);
+
+        if (ed <= bestDistance)
+        {
+            bestDistance = ed;
+            bestMatch = i;
+        }
+    }
+
+    return bestMatch < size ? array[bestMatch] : nullptr;
+}
+
+static void lintComments(LintContext& context, const std::vector<HotComment>& hotcomments)
+{
+    bool seenMode = false;
+
+    for (const HotComment& hc : hotcomments)
+    {
+        // We reserve --!<space> for various informational (non-directive) comments
+        if (hc.content.empty() || hc.content[0] == ' ' || hc.content[0] == '\t')
+            continue;
+
+        if (!hc.header)
+        {
+            emitWarning(context, LintWarning::Code_CommentDirective, hc.location,
+                "Comment directive is ignored because it is placed after the first non-comment token");
+        }
+        else
+        {
+            std::string::size_type space = hc.content.find_first_of(" \t");
+            std::string_view first = std::string_view(hc.content).substr(0, space);
+
+            if (first == "nolint")
+            {
+                std::string::size_type notspace = hc.content.find_first_not_of(" \t", space);
+
+                if (space == std::string::npos || notspace == std::string::npos)
+                {
+                    // disables all lints
+                }
+                else if (LintWarning::parseName(hc.content.c_str() + notspace) == LintWarning::Code_Unknown)
+                {
+                    const char* rule = hc.content.c_str() + notspace;
+
+                    // skip Unknown
+                    if (const char* suggestion = fuzzyMatch(rule, kWarningNames + 1, LintWarning::Code__Count - 1))
+                        emitWarning(context, LintWarning::Code_CommentDirective, hc.location,
+                            "nolint directive refers to unknown lint rule '%s'; did you mean '%s'?", rule, suggestion);
+                    else
+                        emitWarning(
+                            context, LintWarning::Code_CommentDirective, hc.location, "nolint directive refers to unknown lint rule '%s'", rule);
+                }
+            }
+            else if (first == "nocheck" || first == "nonstrict" || first == "strict")
+            {
+                if (space != std::string::npos)
+                    emitWarning(context, LintWarning::Code_CommentDirective, hc.location,
+                        "Comment directive with the type checking mode has extra symbols at the end of the line");
+                else if (seenMode)
+                    emitWarning(context, LintWarning::Code_CommentDirective, hc.location,
+                        "Comment directive with the type checking mode has already been used");
+                else
+                    seenMode = true;
+            }
+            else
+            {
+                static const char* kHotComments[] = {
+                    "nolint",
+                    "nocheck",
+                    "nonstrict",
+                    "strict",
+                };
+
+                if (const char* suggestion = fuzzyMatch(first, kHotComments, std::size(kHotComments)))
+                    emitWarning(context, LintWarning::Code_CommentDirective, hc.location, "Unknown comment directive '%.*s'; did you mean '%s'?",
+                        int(first.size()), first.data(), suggestion);
+                else
+                    emitWarning(context, LintWarning::Code_CommentDirective, hc.location, "Unknown comment directive '%.*s'", int(first.size()),
+                        first.data());
+            }
+        }
+    }
+}
+
 void LintOptions::setDefaults()
 {
     // By default, we enable all warnings
     warningMask = ~0ull;
 }
 
-std::vector<LintWarning> lint(AstStat* root, const AstNameTable& names, const ScopePtr& env, const Module* module, const LintOptions& options)
+std::vector<LintWarning> lint(AstStat* root, const AstNameTable& names, const ScopePtr& env, const Module* module,
+    const std::vector<HotComment>& hotcomments, const LintOptions& options)
 {
     LintContext context;
 
@@ -2609,6 +2707,9 @@ std::vector<LintWarning> lint(AstStat* root, const AstNameTable& names, const Sc
     if (context.warningEnabled(LintWarning::Code_MisleadingAndOr))
         LintMisleadingAndOr::process(context);
 
+    if (context.warningEnabled(LintWarning::Code_CommentDirective))
+        lintComments(context, hotcomments);
+
     std::sort(context.result.begin(), context.result.end(), WarningComparator());
 
     return context.result;
@@ -2630,23 +2731,30 @@ LintWarning::Code LintWarning::parseName(const char* name)
     return Code_Unknown;
 }
 
-uint64_t LintWarning::parseMask(const std::vector<std::string>& hotcomments)
+uint64_t LintWarning::parseMask(const std::vector<HotComment>& hotcomments)
 {
     uint64_t result = 0;
 
-    for (const std::string& hc : hotcomments)
+    for (const HotComment& hc : hotcomments)
     {
-        if (hc.compare(0, 6, "nolint") != 0)
+        if (!hc.header)
             continue;
 
-        std::string::size_type name = hc.find_first_not_of(" \t", 6);
+        if (hc.content.compare(0, 6, "nolint") != 0)
+            continue;
+
+        std::string::size_type name = hc.content.find_first_not_of(" \t", 6);
 
         // --!nolint disables everything
         if (name == std::string::npos)
             return ~0ull;
 
+        // --!nolint needs to be followed by a whitespace character
+        if (name == 6)
+            continue;
+
         // --!nolint name disables the specific lint
-        LintWarning::Code code = LintWarning::parseName(hc.c_str() + name);
+        LintWarning::Code code = LintWarning::parseName(hc.content.c_str() + name);
 
         if (code != LintWarning::Code_Unknown)
             result |= 1ull << int(code);

Analysis/src/Quantify.cpp

@@ -9,14 +9,12 @@ namespace Luau
 
 struct Quantifier
 {
-    ModulePtr module;
     TypeLevel level;
     std::vector<TypeId> generics;
     std::vector<TypePackId> genericPacks;
 
-    Quantifier(ModulePtr module, TypeLevel level)
+    Quantifier(TypeLevel level)
-        : module(module)
+        : level(level)
-        , level(level)
     {
     }
 
@@ -76,9 +74,9 @@ struct Quantifier
     }
 };
 
-void quantify(ModulePtr module, TypeId ty, TypeLevel level)
+void quantify(TypeId ty, TypeLevel level)
 {
-    Quantifier q{std::move(module), level};
+    Quantifier q{level};
     DenseHashSet<void*> seen{nullptr};
     visitTypeVarOnce(ty, q, seen);
 

Analysis/src/Substitution.cpp

@@ -226,27 +226,11 @@ TarjanResult Tarjan::loop()
     return TarjanResult::Ok;
 }
 
-void Tarjan::clear()
-{
-    typeToIndex.clear();
-    indexToType.clear();
-    packToIndex.clear();
-    indexToPack.clear();
-    lowlink.clear();
-    stack.clear();
-    onStack.clear();
-
-    edgesTy.clear();
-    edgesTp.clear();
-    worklist.clear();
-}
-
 TarjanResult Tarjan::visitRoot(TypeId ty)
 {
     childCount = 0;
     ty = log->follow(ty);
 
-    clear();
     auto [index, fresh] = indexify(ty);
     worklist.push_back({index, -1, -1});
     return loop();
@@ -257,7 +241,6 @@ TarjanResult Tarjan::visitRoot(TypePackId tp)
     childCount = 0;
     tp = log->follow(tp);
 
-    clear();
     auto [index, fresh] = indexify(tp);
     worklist.push_back({index, -1, -1});
     return loop();
@@ -314,21 +297,17 @@ void FindDirty::visitSCC(int index)
 
 TarjanResult FindDirty::findDirty(TypeId ty)
 {
-    dirty.clear();
     return visitRoot(ty);
 }
 
 TarjanResult FindDirty::findDirty(TypePackId tp)
 {
-    dirty.clear();
     return visitRoot(tp);
 }
 
 std::optional<TypeId> Substitution::substitute(TypeId ty)
 {
     ty = log->follow(ty);
-    newTypes.clear();
-    newPacks.clear();
 
     auto result = findDirty(ty);
     if (result != TarjanResult::Ok)
@@ -347,8 +326,6 @@ std::optional<TypeId> Substitution::substitute(TypeId ty)
 std::optional<TypePackId> Substitution::substitute(TypePackId tp)
 {
     tp = log->follow(tp);
-    newTypes.clear();
-    newPacks.clear();
 
     auto result = findDirty(tp);
     if (result != TarjanResult::Ok)

Analysis/src/TopoSortStatements.cpp

@@ -26,9 +26,10 @@
  *     3. Cyclic dependencies can be resolved by picking an arbitrary statement to check first.
  */
 
-#include "Luau/Parser.h"
+#include "Luau/Ast.h"
 #include "Luau/DenseHash.h"
 #include "Luau/Common.h"
+#include "Luau/StringUtils.h"
 
 #include <algorithm>
 #include <deque>

Analysis/src/Transpiler.cpp

@@ -933,12 +933,12 @@ struct Printer
 
         writer.symbol(")");
 
-        if (writeTypes && func.hasReturnAnnotation)
+        if (writeTypes && func.returnAnnotation)
         {
             writer.symbol(":");
             writer.space();
 
-            visualizeTypeList(func.returnAnnotation, false);
+            visualizeTypeList(*func.returnAnnotation, false);
         }
 
         visualizeBlock(*func.body);
@@ -989,9 +989,9 @@ struct Printer
         advance(typeAnnotation.location.begin);
         if (const auto& a = typeAnnotation.as<AstTypeReference>())
         {
-            if (a->hasPrefix)
+            if (a->prefix)
             {
-                writer.write(a->prefix.value);
+                writer.write(a->prefix->value);
                 writer.symbol(".");
             }
 

Analysis/src/TypeAttach.cpp

@@ -3,7 +3,6 @@
 
 #include "Luau/Error.h"
 #include "Luau/Module.h"
-#include "Luau/Parser.h"
 #include "Luau/RecursionCounter.h"
 #include "Luau/Scope.h"
 #include "Luau/ToString.h"
@@ -476,12 +475,11 @@ public:
             visitLocal(arg);
         }
 
-        if (!fn->hasReturnAnnotation)
+        if (!fn->returnAnnotation)
         {
             if (auto result = getScope(fn->body->location))
             {
                 TypePackId ret = result->returnType;
-                fn->hasReturnAnnotation = true;
 
                 AstTypePack* variadicAnnotation = nullptr;
                 const auto& [v, tail] = flatten(ret);

Analysis/src/TypeInfer.cpp

@@ -3,7 +3,6 @@
 
 #include "Luau/Common.h"
 #include "Luau/ModuleResolver.h"
-#include "Luau/Parser.h"
 #include "Luau/Quantify.h"
 #include "Luau/RecursionCounter.h"
 #include "Luau/Scope.h"
@@ -24,16 +23,12 @@ LUAU_FASTINTVARIABLE(LuauTypeInferTypePackLoopLimit, 5000)
 LUAU_FASTINTVARIABLE(LuauCheckRecursionLimit, 500)
 LUAU_FASTFLAG(LuauKnowsTheDataModel3)
 LUAU_FASTFLAGVARIABLE(LuauEqConstraint, false)
-LUAU_FASTFLAGVARIABLE(LuauGroupExpectedType, false)
 LUAU_FASTFLAGVARIABLE(LuauWeakEqConstraint, false) // Eventually removed as false.
 LUAU_FASTFLAG(LuauUseCommittingTxnLog)
 LUAU_FASTFLAGVARIABLE(DebugLuauFreezeDuringUnification, false)
 LUAU_FASTFLAGVARIABLE(LuauRecursiveTypeParameterRestriction, false)
 LUAU_FASTFLAGVARIABLE(LuauGenericFunctionsDontCacheTypeParams, false)
-LUAU_FASTFLAGVARIABLE(LuauIfElseBranchTypeUnion, false)
-LUAU_FASTFLAGVARIABLE(LuauIfElseExpectedType2, false)
 LUAU_FASTFLAGVARIABLE(LuauImmutableTypes, false)
-LUAU_FASTFLAGVARIABLE(LuauLengthOnCompositeType, false)
 LUAU_FASTFLAGVARIABLE(LuauNoSealedTypeMod, false)
 LUAU_FASTFLAGVARIABLE(LuauQuantifyInPlace2, false)
 LUAU_FASTFLAGVARIABLE(LuauSealExports, false)
@@ -43,7 +38,6 @@ LUAU_FASTFLAGVARIABLE(LuauTypeAliasDefaults, false)
 LUAU_FASTFLAGVARIABLE(LuauExpectedTypesOfProperties, false)
 LUAU_FASTFLAGVARIABLE(LuauErrorRecoveryType, false)
 LUAU_FASTFLAGVARIABLE(LuauPropertiesGetExpectedType, false)
-LUAU_FASTFLAGVARIABLE(LuauPerModuleUnificationCache, false)
 LUAU_FASTFLAGVARIABLE(LuauProperTypeLevels, false)
 LUAU_FASTFLAGVARIABLE(LuauAscribeCorrectLevelToInferredProperitesOfFreeTables, false)
 LUAU_FASTFLAG(LuauUnionTagMatchFix)
@@ -293,13 +287,10 @@ ModulePtr TypeChecker::check(const SourceModule& module, Mode mode, std::optiona
             GenericError{"Free types leaked into this module's public interface. This is an internal Luau error; please report it."}});
     }
 
-    if (FFlag::LuauPerModuleUnificationCache)
+    // Clear unifier cache since it's keyed off internal types that get deallocated
-    {
+    // This avoids fake cross-module cache hits and keeps cache size at bay when typechecking large module graphs.
-        // Clear unifier cache since it's keyed off internal types that get deallocated
+    unifierState.cachedUnify.clear();
-        // This avoids fake cross-module cache hits and keeps cache size at bay when typechecking large module graphs.
+    unifierState.skipCacheForType.clear();
-        unifierState.cachedUnify.clear();
-        unifierState.skipCacheForType.clear();
-    }
 
     if (FFlag::LuauTwoPassAliasDefinitionFix)
         duplicateTypeAliases.clear();
@@ -509,7 +500,7 @@ LUAU_NOINLINE void TypeChecker::checkBlockTypeAliases(const ScopePtr& scope, std
     {
         if (const auto& typealias = stat->as<AstStatTypeAlias>())
         {
-            if (FFlag::LuauTwoPassAliasDefinitionFix && typealias->name == Parser::errorName)
+            if (FFlag::LuauTwoPassAliasDefinitionFix && typealias->name == kParseNameError)
                 continue;
 
             auto& bindings = typealias->exported ? scope->exportedTypeBindings : scope->privateTypeBindings;
@@ -1193,7 +1184,7 @@ void TypeChecker::check(const ScopePtr& scope, const AstStatTypeAlias& typealias
     Name name = typealias.name.value;
 
     // If the alias is missing a name, we can't do anything with it.  Ignore it.
-    if (FFlag::LuauTwoPassAliasDefinitionFix && name == Parser::errorName)
+    if (FFlag::LuauTwoPassAliasDefinitionFix && name == kParseNameError)
         return;
 
     std::optional<TypeFun> binding;
@@ -1222,7 +1213,8 @@ void TypeChecker::check(const ScopePtr& scope, const AstStatTypeAlias& typealias
             if (FFlag::LuauProperTypeLevels)
                 aliasScope->level.subLevel = subLevel;
 
-            auto [generics, genericPacks] = createGenericTypes(aliasScope, scope->level, typealias, typealias.generics, typealias.genericPacks, /* useCache = */ true);
+            auto [generics, genericPacks] =
+                createGenericTypes(aliasScope, scope->level, typealias, typealias.generics, typealias.genericPacks, /* useCache = */ true);
 
             TypeId ty = freshType(aliasScope);
             FreeTypeVar* ftv = getMutable<FreeTypeVar>(ty);
@@ -1464,7 +1456,7 @@ ExprResult<TypeId> TypeChecker::checkExpr(const ScopePtr& scope, const AstExpr&
     ExprResult<TypeId> result;
 
     if (auto a = expr.as<AstExprGroup>())
-        result = checkExpr(scope, *a->expr, FFlag::LuauGroupExpectedType ? expectedType : std::nullopt);
+        result = checkExpr(scope, *a->expr, expectedType);
     else if (expr.is<AstExprConstantNil>())
         result = {nilType};
     else if (const AstExprConstantBool* bexpr = expr.as<AstExprConstantBool>())
@@ -1508,7 +1500,7 @@ ExprResult<TypeId> TypeChecker::checkExpr(const ScopePtr& scope, const AstExpr&
     else if (auto a = expr.as<AstExprError>())
         result = checkExpr(scope, *a);
     else if (auto a = expr.as<AstExprIfElse>())
-        result = checkExpr(scope, *a, FFlag::LuauIfElseExpectedType2 ? expectedType : std::nullopt);
+        result = checkExpr(scope, *a, expectedType);
     else
         ice("Unhandled AstExpr?");
 
@@ -2093,6 +2085,7 @@ ExprResult<TypeId> TypeChecker::checkExpr(const ScopePtr& scope, const AstExprUn
         return {numberType};
     }
     case AstExprUnary::Len:
+    {
         tablify(operandType);
 
         operandType = stripFromNilAndReport(operandType, expr.location);
@@ -2100,30 +2093,13 @@ ExprResult<TypeId> TypeChecker::checkExpr(const ScopePtr& scope, const AstExprUn
         if (get<ErrorTypeVar>(operandType))
             return {errorRecoveryType(scope)};
 
-        if (FFlag::LuauLengthOnCompositeType)
+        DenseHashSet<TypeId> seen{nullptr};
-        {
-            DenseHashSet<TypeId> seen{nullptr};
 
-            if (!hasLength(operandType, seen, &recursionCount))
+        if (!hasLength(operandType, seen, &recursionCount))
-                reportError(TypeError{expr.location, NotATable{operandType}});
+            reportError(TypeError{expr.location, NotATable{operandType}});
-        }
-        else
-        {
-            if (get<AnyTypeVar>(operandType))
-                return {numberType}; // Not strictly correct: metatables permit overriding this
-
-            if (auto p = get<PrimitiveTypeVar>(operandType))
-            {
-                if (p->type == PrimitiveTypeVar::String)
-                    return {numberType};
-            }
-
-            if (!getTableType(operandType))
-                reportError(TypeError{expr.location, NotATable{operandType}});
-        }
 
         return {numberType};
-
+    }
     default:
         ice("Unknown AstExprUnary " + std::to_string(int(expr.op)));
     }
@@ -2618,22 +2594,11 @@ ExprResult<TypeId> TypeChecker::checkExpr(const ScopePtr& scope, const AstExprIf
     resolve(result.predicates, falseScope, false);
     ExprResult<TypeId> falseType = checkExpr(falseScope, *expr.falseExpr, expectedType);
 
-    if (FFlag::LuauIfElseBranchTypeUnion)
+    if (falseType.type == trueType.type)
-    {
-        if (falseType.type == trueType.type)
-            return {trueType.type};
-
-        std::vector<TypeId> types = reduceUnion({trueType.type, falseType.type});
-        return {types.size() == 1 ? types[0] : addType(UnionTypeVar{std::move(types)})};
-    }
-    else
-    {
-        unify(falseType.type, trueType.type, expr.location);
-
-        // TODO: normalize(UnionTypeVar{{trueType, falseType}})
-        // For now both trueType and falseType must be the same type.
         return {trueType.type};
-    }
+
+    std::vector<TypeId> types = reduceUnion({trueType.type, falseType.type});
+    return {types.size() == 1 ? types[0] : addType(UnionTypeVar{std::move(types)})};
 }
 
 TypeId TypeChecker::checkLValue(const ScopePtr& scope, const AstExpr& expr)
@@ -2986,8 +2951,8 @@ std::pair<TypeId, ScopePtr> TypeChecker::checkFunctionSignature(
     auto [generics, genericPacks] = createGenericTypes(funScope, std::nullopt, expr, expr.generics, expr.genericPacks);
 
     TypePackId retPack;
-    if (expr.hasReturnAnnotation)
+    if (expr.returnAnnotation)
-        retPack = resolveTypePack(funScope, expr.returnAnnotation);
+        retPack = resolveTypePack(funScope, *expr.returnAnnotation);
     else if (isNonstrictMode())
         retPack = anyTypePack;
     else if (expectedFunctionType)
@@ -3181,7 +3146,7 @@ void TypeChecker::checkFunctionBody(const ScopePtr& scope, TypeId ty, const AstE
             // If we're in nonstrict mode we want to only report this missing return
             // statement if there are type annotations on the function. In strict mode
             // we report it regardless.
-            if (!isNonstrictMode() || function.hasReturnAnnotation)
+            if (!isNonstrictMode() || function.returnAnnotation)
             {
                 reportError(getEndLocation(function), FunctionExitsWithoutReturning{funTy->retType});
             }
@@ -4403,11 +4368,7 @@ TypeId Instantiation::clean(TypeId ty)
 
     // Annoyingly, we have to do this even if there are no generics,
     // to replace any generic tables.
-    replaceGenerics.log = log;
+    ReplaceGenerics replaceGenerics{log, arena, level, ftv->generics, ftv->genericPacks};
-    replaceGenerics.level = level;
-    replaceGenerics.currentModule = currentModule;
-    replaceGenerics.generics.assign(ftv->generics.begin(), ftv->generics.end());
-    replaceGenerics.genericPacks.assign(ftv->genericPacks.begin(), ftv->genericPacks.end());
 
     // TODO: What to do if this returns nullopt?
     // We don't have access to the error-reporting machinery
@@ -4573,16 +4534,11 @@ TypeId TypeChecker::quantify(const ScopePtr& scope, TypeId ty, Location location
 
     if (FFlag::LuauQuantifyInPlace2)
     {
-        Luau::quantify(currentModule, ty, scope->level);
+        Luau::quantify(ty, scope->level);
         return ty;
     }
 
-    quantification.log = TxnLog::empty();
+    Quantification quantification{&currentModule->internalTypes, scope->level};
-    quantification.level = scope->level;
-    quantification.generics.clear();
-    quantification.genericPacks.clear();
-    quantification.currentModule = currentModule;
-
     std::optional<TypeId> qty = quantification.substitute(ty);
 
     if (!qty.has_value())
@@ -4596,18 +4552,14 @@ TypeId TypeChecker::quantify(const ScopePtr& scope, TypeId ty, Location location
 
     FunctionTypeVar* qftv = getMutable<FunctionTypeVar>(*qty);
     LUAU_ASSERT(qftv);
-    qftv->generics = quantification.generics;
+    qftv->generics = std::move(quantification.generics);
-    qftv->genericPacks = quantification.genericPacks;
+    qftv->genericPacks = std::move(quantification.genericPacks);
     return *qty;
 }
 
 TypeId TypeChecker::instantiate(const ScopePtr& scope, TypeId ty, Location location, const TxnLog* log)
 {
-    LUAU_ASSERT(log != nullptr);
+    Instantiation instantiation{FFlag::LuauUseCommittingTxnLog ? log : TxnLog::empty(), &currentModule->internalTypes, scope->level};
-
-    instantiation.log = FFlag::LuauUseCommittingTxnLog ? log : TxnLog::empty();
-    instantiation.level = scope->level;
-    instantiation.currentModule = currentModule;
     std::optional<TypeId> instantiated = instantiation.substitute(ty);
     if (instantiated.has_value())
         return *instantiated;
@@ -4620,10 +4572,7 @@ TypeId TypeChecker::instantiate(const ScopePtr& scope, TypeId ty, Location locat
 
 TypeId TypeChecker::anyify(const ScopePtr& scope, TypeId ty, Location location)
 {
-    anyification.log = TxnLog::empty();
+    Anyification anyification{&currentModule->internalTypes, anyType, anyTypePack};
-    anyification.anyType = anyType;
-    anyification.anyTypePack = anyTypePack;
-    anyification.currentModule = currentModule;
     std::optional<TypeId> any = anyification.substitute(ty);
     if (any.has_value())
         return *any;
@@ -4636,10 +4585,7 @@ TypeId TypeChecker::anyify(const ScopePtr& scope, TypeId ty, Location location)
 
 TypePackId TypeChecker::anyify(const ScopePtr& scope, TypePackId ty, Location location)
 {
-    anyification.log = TxnLog::empty();
+    Anyification anyification{&currentModule->internalTypes, anyType, anyTypePack};
-    anyification.anyType = anyType;
-    anyification.anyTypePack = anyTypePack;
-    anyification.currentModule = currentModule;
     std::optional<TypePackId> any = anyification.substitute(ty);
     if (any.has_value())
         return *any;
@@ -4823,7 +4769,8 @@ TypePackId TypeChecker::errorRecoveryTypePack(TypePackId guess)
     return getSingletonTypes().errorRecoveryTypePack(guess);
 }
 
-TypeIdPredicate TypeChecker::mkTruthyPredicate(bool sense) {
+TypeIdPredicate TypeChecker::mkTruthyPredicate(bool sense)
+{
     return [this, sense](TypeId ty) -> std::optional<TypeId> {
         // any/error/free gets a special pass unconditionally because they can't be decided.
         if (get<AnyTypeVar>(ty) || get<ErrorTypeVar>(ty) || get<FreeTypeVar>(ty))
@@ -4904,8 +4851,8 @@ TypeId TypeChecker::resolveType(const ScopePtr& scope, const AstType& annotation
     if (const auto& lit = annotation.as<AstTypeReference>())
     {
         std::optional<TypeFun> tf;
-        if (lit->hasPrefix)
+        if (lit->prefix)
-            tf = scope->lookupImportedType(lit->prefix.value, lit->name.value);
+            tf = scope->lookupImportedType(lit->prefix->value, lit->name.value);
 
         else if (FFlag::DebugLuauMagicTypes && lit->name == "_luau_ice")
             ice("_luau_ice encountered", lit->location);
@@ -4932,12 +4879,12 @@ TypeId TypeChecker::resolveType(const ScopePtr& scope, const AstType& annotation
 
         if (!tf)
         {
-            if (lit->name == Parser::errorName)
+            if (lit->name == kParseNameError)
                 return errorRecoveryType(scope);
 
             std::string typeName;
-            if (lit->hasPrefix)
+            if (lit->prefix)
-                typeName = std::string(lit->prefix.value) + ".";
+                typeName = std::string(lit->prefix->value) + ".";
             typeName += lit->name.value;
 
             if (scope->lookupPack(typeName))
@@ -5038,12 +4985,7 @@ TypeId TypeChecker::resolveType(const ScopePtr& scope, const AstType& annotation
             if (notEnoughParameters && hasDefaultParameters)
             {
                 // 'applyTypeFunction' is used to substitute default types that reference previous generic types
-                applyTypeFunction.log = TxnLog::empty();
+                ApplyTypeFunction applyTypeFunction{&currentModule->internalTypes, scope->level};
-                applyTypeFunction.typeArguments.clear();
-                applyTypeFunction.typePackArguments.clear();
-                applyTypeFunction.currentModule = currentModule;
-                applyTypeFunction.level = scope->level;
-                applyTypeFunction.encounteredForwardedType = false;
 
                 for (size_t i = 0; i < typesProvided; ++i)
                     applyTypeFunction.typeArguments[tf->typeParams[i].ty] = typeParams[i];
@@ -5362,18 +5304,14 @@ TypeId TypeChecker::instantiateTypeFun(const ScopePtr& scope, const TypeFun& tf,
     if (tf.typeParams.empty() && tf.typePackParams.empty())
         return tf.type;
 
-    applyTypeFunction.typeArguments.clear();
+    ApplyTypeFunction applyTypeFunction{&currentModule->internalTypes, scope->level};
+
     for (size_t i = 0; i < tf.typeParams.size(); ++i)
         applyTypeFunction.typeArguments[tf.typeParams[i].ty] = typeParams[i];
 
-    applyTypeFunction.typePackArguments.clear();
     for (size_t i = 0; i < tf.typePackParams.size(); ++i)
         applyTypeFunction.typePackArguments[tf.typePackParams[i].tp] = typePackParams[i];
 
-    applyTypeFunction.log = TxnLog::empty();
-    applyTypeFunction.currentModule = currentModule;
-    applyTypeFunction.level = scope->level;
-    applyTypeFunction.encounteredForwardedType = false;
     std::optional<TypeId> maybeInstantiated = applyTypeFunction.substitute(tf.type);
     if (!maybeInstantiated.has_value())
     {

Analysis/src/TypeUtils.cpp

@@ -5,6 +5,8 @@
 #include "Luau/ToString.h"
 #include "Luau/TypeInfer.h"
 
+LUAU_FASTFLAGVARIABLE(LuauTerminateCyclicMetatableIndexLookup, false)
+
 namespace Luau
 {
 
@@ -48,9 +50,19 @@ std::optional<TypeId> findTablePropertyRespectingMeta(ErrorVec& errors, const Sc
     }
 
     std::optional<TypeId> mtIndex = findMetatableEntry(errors, globalScope, ty, "__index", location);
+    int count = 0;
     while (mtIndex)
     {
         TypeId index = follow(*mtIndex);
+
+        if (FFlag::LuauTerminateCyclicMetatableIndexLookup)
+        {
+            if (count >= 100)
+                return std::nullopt;
+
+            ++count;
+        }
+
         if (const auto& itt = getTableType(index))
         {
             const auto& fit = itt->props.find(name);

Analysis/src/TypeVar.cpp

@@ -23,8 +23,6 @@ LUAU_FASTFLAG(DebugLuauFreezeArena)
 LUAU_FASTINTVARIABLE(LuauTypeMaximumStringifierLength, 500)
 LUAU_FASTINTVARIABLE(LuauTableTypeMaximumStringifierLength, 0)
 LUAU_FASTINT(LuauTypeInferRecursionLimit)
-LUAU_FASTFLAG(LuauLengthOnCompositeType)
-LUAU_FASTFLAGVARIABLE(LuauMetatableAreEqualRecursion, false)
 LUAU_FASTFLAGVARIABLE(LuauRefactorTypeVarQuestions, false)
 LUAU_FASTFLAG(LuauErrorRecoveryType)
 LUAU_FASTFLAG(LuauUnionTagMatchFix)
@@ -385,8 +383,6 @@ bool maybeSingleton(TypeId ty)
 
 bool hasLength(TypeId ty, DenseHashSet<TypeId>& seen, int* recursionCount)
 {
-    LUAU_ASSERT(FFlag::LuauLengthOnCompositeType);
-
     RecursionLimiter _rl(recursionCount, FInt::LuauTypeInferRecursionLimit);
 
     ty = follow(ty);
@@ -555,7 +551,7 @@ bool areEqual(SeenSet& seen, const TableTypeVar& lhs, const TableTypeVar& rhs)
 
 static bool areEqual(SeenSet& seen, const MetatableTypeVar& lhs, const MetatableTypeVar& rhs)
 {
-    if (FFlag::LuauMetatableAreEqualRecursion && areSeen(seen, &lhs, &rhs))
+    if (areSeen(seen, &lhs, &rhs))
         return true;
 
     return areEqual(seen, *lhs.table, *rhs.table) && areEqual(seen, *lhs.metatable, *rhs.metatable);

Analysis/src/TypedAllocator.cpp

@@ -7,6 +7,9 @@
 #ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
 #endif
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif
 #include <Windows.h>
 
 const size_t kPageSize = 4096;

Analysis/src/Unifier.cpp

@@ -14,7 +14,6 @@
 
 LUAU_FASTINT(LuauTypeInferRecursionLimit);
 LUAU_FASTINT(LuauTypeInferTypePackLoopLimit);
-LUAU_FASTFLAGVARIABLE(LuauCommittingTxnLogFreeTpPromote, false)
 LUAU_FASTFLAG(LuauImmutableTypes)
 LUAU_FASTFLAG(LuauUseCommittingTxnLog)
 LUAU_FASTINTVARIABLE(LuauTypeInferIterationLimit, 2000);
@@ -23,7 +22,6 @@ LUAU_FASTFLAGVARIABLE(LuauTableUnificationEarlyTest, false)
 LUAU_FASTFLAG(LuauSingletonTypes)
 LUAU_FASTFLAG(LuauErrorRecoveryType);
 LUAU_FASTFLAG(LuauProperTypeLevels);
-LUAU_FASTFLAGVARIABLE(LuauUnifyPackTails, false)
 LUAU_FASTFLAGVARIABLE(LuauUnionTagMatchFix, false)
 LUAU_FASTFLAGVARIABLE(LuauFollowWithCommittingTxnLogInAnyUnification, false)
 
@@ -116,7 +114,7 @@ struct PromoteTypeLevels
     {
         // Surprise, it's actually a BoundTypePack that hasn't been committed yet.
         // Calling getMutable on this will trigger an assertion.
-        if (FFlag::LuauCommittingTxnLogFreeTpPromote && FFlag::LuauUseCommittingTxnLog && !log.is<FreeTypePack>(tp))
+        if (FFlag::LuauUseCommittingTxnLog && !log.is<FreeTypePack>(tp))
             return true;
 
         promote(tp, FFlag::LuauUseCommittingTxnLog ? log.getMutable<FreeTypePack>(tp) : getMutable<FreeTypePack>(tp));
@@ -1242,7 +1240,7 @@ void Unifier::tryUnify_(TypePackId subTp, TypePackId superTp, bool isFunctionCal
                 // If both are at the end, we're done
                 if (!superIter.good() && !subIter.good())
                 {
-                    if (FFlag::LuauUnifyPackTails && subTpv->tail && superTpv->tail)
+                    if (subTpv->tail && superTpv->tail)
                     {
                         tryUnify_(*subTpv->tail, *superTpv->tail);
                         break;
@@ -1250,9 +1248,7 @@ void Unifier::tryUnify_(TypePackId subTp, TypePackId superTp, bool isFunctionCal
 
                     const bool lFreeTail = superTpv->tail && log.getMutable<FreeTypePack>(log.follow(*superTpv->tail)) != nullptr;
                     const bool rFreeTail = subTpv->tail && log.getMutable<FreeTypePack>(log.follow(*subTpv->tail)) != nullptr;
-                    if (!FFlag::LuauUnifyPackTails && lFreeTail && rFreeTail)
+                    if (lFreeTail)
-                        tryUnify_(*subTpv->tail, *superTpv->tail);
-                    else if (lFreeTail)
                         tryUnify_(emptyTp, *superTpv->tail);
                     else if (rFreeTail)
                         tryUnify_(emptyTp, *subTpv->tail);
@@ -1448,7 +1444,7 @@ void Unifier::tryUnify_(TypePackId subTp, TypePackId superTp, bool isFunctionCal
                 // If both are at the end, we're done
                 if (!superIter.good() && !subIter.good())
                 {
-                    if (FFlag::LuauUnifyPackTails && subTpv->tail && superTpv->tail)
+                    if (subTpv->tail && superTpv->tail)
                     {
                         tryUnify_(*subTpv->tail, *superTpv->tail);
                         break;
@@ -1456,9 +1452,7 @@ void Unifier::tryUnify_(TypePackId subTp, TypePackId superTp, bool isFunctionCal
 
                     const bool lFreeTail = superTpv->tail && get<FreeTypePack>(follow(*superTpv->tail)) != nullptr;
                     const bool rFreeTail = subTpv->tail && get<FreeTypePack>(follow(*subTpv->tail)) != nullptr;
-                    if (!FFlag::LuauUnifyPackTails && lFreeTail && rFreeTail)
+                    if (lFreeTail)
-                        tryUnify_(*subTpv->tail, *superTpv->tail);
-                    else if (lFreeTail)
                         tryUnify_(emptyTp, *superTpv->tail);
                     else if (rFreeTail)
                         tryUnify_(emptyTp, *subTpv->tail);

Ast/include/Luau/Ast.h

@@ -594,8 +594,7 @@ public:
     AstArray<AstGenericTypePack> genericPacks;
     AstLocal* self;
     AstArray<AstLocal*> args;
-    bool hasReturnAnnotation;
+    std::optional<AstTypeList> returnAnnotation;
-    AstTypeList returnAnnotation;
     bool vararg = false;
     Location varargLocation;
     AstTypePack* varargAnnotation;
@@ -740,7 +739,7 @@ class AstStatIf : public AstStat
 public:
     LUAU_RTTI(AstStatIf)
 
-    AstStatIf(const Location& location, AstExpr* condition, AstStatBlock* thenbody, AstStat* elsebody, bool hasThen, const Location& thenLocation,
+    AstStatIf(const Location& location, AstExpr* condition, AstStatBlock* thenbody, AstStat* elsebody, const std::optional<Location>& thenLocation,
         const std::optional<Location>& elseLocation, bool hasEnd);
 
     void visit(AstVisitor* visitor) override;
@@ -749,12 +748,10 @@ public:
     AstStatBlock* thenbody;
     AstStat* elsebody;
 
-    bool hasThen = false;
+    std::optional<Location> thenLocation;
-    Location thenLocation;
 
     // Active for 'elseif' as well
-    bool hasElse = false;
+    std::optional<Location> elseLocation;
-    Location elseLocation;
 
     bool hasEnd = false;
 };
@@ -849,8 +846,7 @@ public:
     AstArray<AstLocal*> vars;
     AstArray<AstExpr*> values;
 
-    bool hasEqualsSign = false;
+    std::optional<Location> equalsSignLocation;
-    Location equalsSignLocation;
 };
 
 class AstStatFor : public AstStat
@@ -1053,9 +1049,8 @@ public:
 
     void visit(AstVisitor* visitor) override;
 
-    bool hasPrefix;
     bool hasParameterList;
-    AstName prefix;
+    std::optional<AstName> prefix;
     AstName name;
     AstArray<AstTypeOrPack> parameters;
 };

Ast/include/Luau/Lexer.h

@@ -233,4 +233,9 @@ private:
     bool readNames;
 };
 
+inline bool isSpace(char ch)
+{
+    return ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n' || ch == '\v' || ch == '\f';
+}
+
 } // namespace Luau

Ast/include/Luau/ParseResult.h

@@ -0,0 +1,69 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#pragma once
+
+#include "Luau/Common.h"
+#include "Luau/Location.h"
+#include "Luau/Lexer.h"
+#include "Luau/StringUtils.h"
+
+namespace Luau
+{
+
+class AstStatBlock;
+
+class ParseError : public std::exception
+{
+public:
+    ParseError(const Location& location, const std::string& message);
+
+    virtual const char* what() const throw();
+
+    const Location& getLocation() const;
+    const std::string& getMessage() const;
+
+    static LUAU_NORETURN void raise(const Location& location, const char* format, ...) LUAU_PRINTF_ATTR(2, 3);
+
+private:
+    Location location;
+    std::string message;
+};
+
+class ParseErrors : public std::exception
+{
+public:
+    ParseErrors(std::vector<ParseError> errors);
+
+    virtual const char* what() const throw();
+
+    const std::vector<ParseError>& getErrors() const;
+
+private:
+    std::vector<ParseError> errors;
+    std::string message;
+};
+
+struct HotComment
+{
+    bool header;
+    Location location;
+    std::string content;
+};
+
+struct Comment
+{
+    Lexeme::Type type; // Comment, BlockComment, or BrokenComment
+    Location location;
+};
+
+struct ParseResult
+{
+    AstStatBlock* root;
+    std::vector<HotComment> hotcomments;
+    std::vector<ParseError> errors;
+
+    std::vector<Comment> commentLocations;
+};
+
+static constexpr const char* kParseNameError = "%error-id%";
+
+} // namespace Luau

Ast/include/Luau/Parser.h

@@ -4,6 +4,7 @@
 #include "Luau/Ast.h"
 #include "Luau/Lexer.h"
 #include "Luau/ParseOptions.h"
+#include "Luau/ParseResult.h"
 #include "Luau/StringUtils.h"
 #include "Luau/DenseHash.h"
 #include "Luau/Common.h"
@@ -14,37 +15,6 @@
 namespace Luau
 {
 
-class ParseError : public std::exception
-{
-public:
-    ParseError(const Location& location, const std::string& message);
-
-    virtual const char* what() const throw();
-
-    const Location& getLocation() const;
-    const std::string& getMessage() const;
-
-    static LUAU_NORETURN void raise(const Location& location, const char* format, ...) LUAU_PRINTF_ATTR(2, 3);
-
-private:
-    Location location;
-    std::string message;
-};
-
-class ParseErrors : public std::exception
-{
-public:
-    ParseErrors(std::vector<ParseError> errors);
-
-    virtual const char* what() const throw();
-
-    const std::vector<ParseError>& getErrors() const;
-
-private:
-    std::vector<ParseError> errors;
-    std::string message;
-};
-
 template<typename T>
 class TempVector
 {
@@ -80,34 +50,17 @@ private:
     size_t size_;
 };
 
-struct Comment
-{
-    Lexeme::Type type; // Comment, BlockComment, or BrokenComment
-    Location location;
-};
-
-struct ParseResult
-{
-    AstStatBlock* root;
-    std::vector<std::string> hotcomments;
-    std::vector<ParseError> errors;
-
-    std::vector<Comment> commentLocations;
-};
-
 class Parser
 {
 public:
     static ParseResult parse(
         const char* buffer, std::size_t bufferSize, AstNameTable& names, Allocator& allocator, ParseOptions options = ParseOptions());
 
-    static constexpr const char* errorName = "%error-id%";
-
 private:
     struct Name;
     struct Binding;
 
-    Parser(const char* buffer, std::size_t bufferSize, AstNameTable& names, Allocator& allocator);
+    Parser(const char* buffer, std::size_t bufferSize, AstNameTable& names, Allocator& allocator, const ParseOptions& options);
 
     bool blockFollow(const Lexeme& l);
 
@@ -330,7 +283,7 @@ private:
     AstTypeError* reportTypeAnnotationError(const Location& location, const AstArray<AstType*>& types, bool isMissing, const char* format, ...)
         LUAU_PRINTF_ATTR(5, 6);
 
-    const Lexeme& nextLexeme();
+    void nextLexeme();
 
     struct Function
     {
@@ -386,6 +339,9 @@ private:
     Allocator& allocator;
 
     std::vector<Comment> commentLocations;
+    std::vector<HotComment> hotcomments;
+
+    bool hotcommentHeader = true;
 
     unsigned int recursionCounter;
 

Ast/src/Ast.cpp

@@ -167,8 +167,7 @@ AstExprFunction::AstExprFunction(const Location& location, const AstArray<AstGen
     , genericPacks(genericPacks)
     , self(self)
     , args(args)
-    , hasReturnAnnotation(returnAnnotation.has_value())
+    , returnAnnotation(returnAnnotation)
-    , returnAnnotation()
     , vararg(vararg.has_value())
     , varargLocation(vararg.value_or(Location()))
     , varargAnnotation(varargAnnotation)
@@ -178,8 +177,6 @@ AstExprFunction::AstExprFunction(const Location& location, const AstArray<AstGen
     , hasEnd(hasEnd)
     , argLocation(argLocation)
 {
-    if (returnAnnotation.has_value())
-        this->returnAnnotation = *returnAnnotation;
 }
 
 void AstExprFunction::visit(AstVisitor* visitor)
@@ -195,8 +192,8 @@ void AstExprFunction::visit(AstVisitor* visitor)
         if (varargAnnotation)
             varargAnnotation->visit(visitor);
 
-        if (hasReturnAnnotation)
+        if (returnAnnotation)
-            visitTypeList(visitor, returnAnnotation);
+            visitTypeList(visitor, *returnAnnotation);
 
         body->visit(visitor);
     }
@@ -375,21 +372,16 @@ void AstStatBlock::visit(AstVisitor* visitor)
     }
 }
 
-AstStatIf::AstStatIf(const Location& location, AstExpr* condition, AstStatBlock* thenbody, AstStat* elsebody, bool hasThen,
+AstStatIf::AstStatIf(const Location& location, AstExpr* condition, AstStatBlock* thenbody, AstStat* elsebody,
-    const Location& thenLocation, const std::optional<Location>& elseLocation, bool hasEnd)
+    const std::optional<Location>& thenLocation, const std::optional<Location>& elseLocation, bool hasEnd)
     : AstStat(ClassIndex(), location)
     , condition(condition)
     , thenbody(thenbody)
     , elsebody(elsebody)
-    , hasThen(hasThen)
     , thenLocation(thenLocation)
+    , elseLocation(elseLocation)
     , hasEnd(hasEnd)
 {
-    if (bool(elseLocation))
-    {
-        hasElse = true;
-        this->elseLocation = *elseLocation;
-    }
 }
 
 void AstStatIf::visit(AstVisitor* visitor)
@@ -492,12 +484,8 @@ AstStatLocal::AstStatLocal(
     : AstStat(ClassIndex(), location)
     , vars(vars)
     , values(values)
+    , equalsSignLocation(equalsSignLocation)
 {
-    if (bool(equalsSignLocation))
-    {
-        hasEqualsSign = true;
-        this->equalsSignLocation = *equalsSignLocation;
-    }
 }
 
 void AstStatLocal::visit(AstVisitor* visitor)
@@ -750,9 +738,8 @@ void AstStatError::visit(AstVisitor* visitor)
 AstTypeReference::AstTypeReference(
     const Location& location, std::optional<AstName> prefix, AstName name, bool hasParameterList, const AstArray<AstTypeOrPack>& parameters)
     : AstType(ClassIndex(), location)
-    , hasPrefix(bool(prefix))
     , hasParameterList(hasParameterList)
-    , prefix(prefix ? *prefix : AstName())
+    , prefix(prefix)
     , name(name)
     , parameters(parameters)
 {

Ast/src/Lexer.cpp

@@ -101,11 +101,6 @@ Lexeme::Lexeme(const Location& location, Type type, const char* name)
     LUAU_ASSERT(type == Name || (type >= Reserved_BEGIN && type < Lexeme::Reserved_END));
 }
 
-static bool isComment(const Lexeme& lexeme)
-{
-    return lexeme.type == Lexeme::Comment || lexeme.type == Lexeme::BlockComment;
-}
-
 static const char* kReserved[] = {"and", "break", "do", "else", "elseif", "end", "false", "for", "function", "if", "in", "local", "nil", "not", "or",
     "repeat", "return", "then", "true", "until", "while"};
 
@@ -282,11 +277,6 @@ AstName AstNameTable::get(const char* name) const
     return getWithType(name, strlen(name)).first;
 }
 
-inline bool isSpace(char ch)
-{
-    return ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n' || ch == '\v' || ch == '\f';
-}
-
 inline bool isAlpha(char ch)
 {
     // use or trick to convert to lower case and unsigned comparison to do range check
@@ -372,7 +362,7 @@ const Lexeme& Lexer::next(bool skipComments)
         prevLocation = lexeme.location;
 
         lexeme = readNext();
-    } while (skipComments && isComment(lexeme));
+    } while (skipComments && (lexeme.type == Lexeme::Comment || lexeme.type == Lexeme::BlockComment));
 
     return lexeme;
 }

Ast/src/Parser.cpp

@@ -13,18 +13,15 @@ LUAU_FASTINTVARIABLE(LuauParseErrorLimit, 100)
 LUAU_FASTFLAGVARIABLE(LuauParseSingletonTypes, false)
 LUAU_FASTFLAGVARIABLE(LuauParseTypeAliasDefaults, false)
 LUAU_FASTFLAGVARIABLE(LuauParseRecoverTypePackEllipsis, false)
-LUAU_FASTFLAGVARIABLE(LuauStartingBrokenComment, false)
+LUAU_FASTFLAGVARIABLE(LuauParseAllHotComments, false)
+LUAU_FASTFLAGVARIABLE(LuauTableFieldFunctionDebugname, false)
 
 namespace Luau
 {
 
-inline bool isSpace(char ch)
-{
-    return ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n' || ch == '\v' || ch == '\f';
-}
-
 static bool isComment(const Lexeme& lexeme)
 {
+    LUAU_ASSERT(!FFlag::LuauParseAllHotComments);
     return lexeme.type == Lexeme::Comment || lexeme.type == Lexeme::BlockComment;
 }
 
@@ -151,31 +148,37 @@ ParseResult Parser::parse(const char* buffer, size_t bufferSize, AstNameTable& n
 {
     LUAU_TIMETRACE_SCOPE("Parser::parse", "Parser");
 
-    Parser p(buffer, bufferSize, names, allocator);
+    Parser p(buffer, bufferSize, names, allocator, FFlag::LuauParseAllHotComments ? options : ParseOptions());
 
     try
     {
-        std::vector<std::string> hotcomments;
+        if (FFlag::LuauParseAllHotComments)
-
-        while (isComment(p.lexer.current()) || p.lexer.current().type == Lexeme::BrokenComment)
         {
-            const char* text = p.lexer.current().data;
+            AstStatBlock* root = p.parseChunk();
-            unsigned int length = p.lexer.current().length;
 
-            if (length && text[0] == '!')
+            return ParseResult{root, std::move(p.hotcomments), std::move(p.parseErrors), std::move(p.commentLocations)};
+        }
+        else
+        {
+            std::vector<HotComment> hotcomments;
+
+            while (isComment(p.lexer.current()) || p.lexer.current().type == Lexeme::BrokenComment)
             {
-                unsigned int end = length;
+                const char* text = p.lexer.current().data;
-                while (end > 0 && isSpace(text[end - 1]))
+                unsigned int length = p.lexer.current().length;
-                    --end;
 
-                hotcomments.push_back(std::string(text + 1, text + end));
+                if (length && text[0] == '!')
-            }
+                {
+                    unsigned int end = length;
+                    while (end > 0 && isSpace(text[end - 1]))
+                        --end;
 
-            const Lexeme::Type type = p.lexer.current().type;
+                    hotcomments.push_back({true, p.lexer.current().location, std::string(text + 1, text + end)});
-            const Location loc = p.lexer.current().location;
+                }
+
+                const Lexeme::Type type = p.lexer.current().type;
+                const Location loc = p.lexer.current().location;
 
-            if (FFlag::LuauStartingBrokenComment)
-            {
                 if (options.captureComments)
                     p.commentLocations.push_back(Comment{type, loc});
 
@@ -184,22 +187,15 @@ ParseResult Parser::parse(const char* buffer, size_t bufferSize, AstNameTable& n
 
                 p.lexer.next();
             }
-            else
-            {
-                p.lexer.next();
 
-                if (options.captureComments)
+            p.lexer.setSkipComments(true);
-                    p.commentLocations.push_back(Comment{type, loc});
+
-            }
+            p.options = options;
+
+            AstStatBlock* root = p.parseChunk();
+
+            return ParseResult{root, hotcomments, p.parseErrors, std::move(p.commentLocations)};
         }
-
-        p.lexer.setSkipComments(true);
-
-        p.options = options;
-
-        AstStatBlock* root = p.parseChunk();
-
-        return ParseResult{root, hotcomments, p.parseErrors, std::move(p.commentLocations)};
     }
     catch (ParseError& err)
     {
@@ -210,8 +206,9 @@ ParseResult Parser::parse(const char* buffer, size_t bufferSize, AstNameTable& n
     }
 }
 
-Parser::Parser(const char* buffer, size_t bufferSize, AstNameTable& names, Allocator& allocator)
+Parser::Parser(const char* buffer, size_t bufferSize, AstNameTable& names, Allocator& allocator, const ParseOptions& options)
-    : lexer(buffer, bufferSize, names)
+    : options(options)
+    , lexer(buffer, bufferSize, names)
     , allocator(allocator)
     , recursionCounter(0)
     , endMismatchSuspect(Location(), Lexeme::Eof)
@@ -224,14 +221,20 @@ Parser::Parser(const char* buffer, size_t bufferSize, AstNameTable& names, Alloc
 
     nameSelf = names.addStatic("self");
     nameNumber = names.addStatic("number");
-    nameError = names.addStatic(errorName);
+    nameError = names.addStatic(kParseNameError);
     nameNil = names.getOrAdd("nil"); // nil is a reserved keyword
 
     matchRecoveryStopOnToken.assign(Lexeme::Type::Reserved_END, 0);
     matchRecoveryStopOnToken[Lexeme::Type::Eof] = 1;
 
+    if (FFlag::LuauParseAllHotComments)
+        lexer.setSkipComments(true);
+
     // read first lexeme
     nextLexeme();
+
+    // all hot comments parsed after the first non-comment lexeme are special in that they don't affect type checking / linting mode
+    hotcommentHeader = false;
 }
 
 bool Parser::blockFollow(const Lexeme& l)
@@ -396,7 +399,9 @@ AstStat* Parser::parseIf()
     AstExpr* cond = parseExpr();
 
     Lexeme matchThen = lexer.current();
-    bool hasThen = expectAndConsume(Lexeme::ReservedThen, "if statement");
+    std::optional<Location> thenLocation;
+    if (expectAndConsume(Lexeme::ReservedThen, "if statement"))
+        thenLocation = matchThen.location;
 
     AstStatBlock* thenbody = parseBlock();
 
@@ -434,7 +439,7 @@ AstStat* Parser::parseIf()
         hasEnd = expectMatchEndAndConsume(Lexeme::ReservedEnd, matchThenElse);
     }
 
-    return allocator.alloc<AstStatIf>(Location(start, end), cond, thenbody, elsebody, hasThen, matchThen.location, elseLocation, hasEnd);
+    return allocator.alloc<AstStatIf>(Location(start, end), cond, thenbody, elsebody, thenLocation, elseLocation, hasEnd);
 }
 
 // while exp do block end
@@ -769,7 +774,7 @@ AstStat* Parser::parseTypeAlias(const Location& start, bool exported)
 {
     // note: `type` token is already parsed for us, so we just need to parse the rest
 
-    auto name = parseNameOpt("type name");
+    std::optional<Name> name = parseNameOpt("type name");
 
     // Use error name if the name is missing
     if (!name)
@@ -925,7 +930,7 @@ AstStat* Parser::parseDeclaration(const Location& start)
 
         return allocator.alloc<AstStatDeclareClass>(Location(classStart, classEnd), className.name, superName, copy(props));
     }
-    else if (auto globalName = parseNameOpt("global variable name"))
+    else if (std::optional<Name> globalName = parseNameOpt("global variable name"))
     {
         expectAndConsume(':', "global variable declaration");
 
@@ -1066,7 +1071,7 @@ void Parser::parseExprList(TempVector<AstExpr*>& result)
 
 Parser::Binding Parser::parseBinding()
 {
-    auto name = parseNameOpt("variable name");
+    std::optional<Name> name = parseNameOpt("variable name");
 
     // Use placeholder if the name is missing
     if (!name)
@@ -1325,7 +1330,7 @@ AstType* Parser::parseTableTypeAnnotation()
         }
         else
         {
-            auto name = parseNameOpt("table field");
+            std::optional<Name> name = parseNameOpt("table field");
 
             if (!name)
                 break;
@@ -1422,7 +1427,7 @@ AstType* Parser::parseFunctionTypeAnnotationTail(const Lexeme& begin, AstArray<A
         expectAndConsume(Lexeme::SkinnyArrow, "function type");
     }
 
-    const auto [endLocation, returnTypeList] = parseReturnTypeAnnotation();
+    auto [endLocation, returnTypeList] = parseReturnTypeAnnotation();
 
     AstTypeList paramTypes = AstTypeList{params, varargAnnotation};
     return allocator.alloc<AstTypeFunction>(Location(begin.location, endLocation), generics, genericPacks, paramTypes, paramNames, returnTypeList);
@@ -1869,7 +1874,7 @@ AstExpr* Parser::parseExpr(unsigned int limit)
 // NAME
 AstExpr* Parser::parseNameExpr(const char* context)
 {
-    auto name = parseNameOpt(context);
+    std::optional<Name> name = parseNameOpt(context);
 
     if (!name)
         return allocator.alloc<AstExprError>(lexer.current().location, copy<AstExpr*>({}), unsigned(parseErrors.size() - 1));
@@ -2233,6 +2238,12 @@ AstExpr* Parser::parseTableConstructor()
             AstExpr* key = allocator.alloc<AstExprConstantString>(name.location, nameString);
             AstExpr* value = parseExpr();
 
+            if (FFlag::LuauTableFieldFunctionDebugname)
+            {
+                if (AstExprFunction* func = value->as<AstExprFunction>())
+                    func->debugname = name.name;
+            }
+
             items.push_back({AstExprTable::Item::Record, key, value});
         }
         else
@@ -2313,7 +2324,7 @@ std::optional<Parser::Name> Parser::parseNameOpt(const char* context)
 
 Parser::Name Parser::parseName(const char* context)
 {
-    if (auto name = parseNameOpt(context))
+    if (std::optional<Name> name = parseNameOpt(context))
         return *name;
 
     Location location = lexer.current().location;
@@ -2324,7 +2335,7 @@ Parser::Name Parser::parseName(const char* context)
 
 Parser::Name Parser::parseIndexName(const char* context, const Position& previous)
 {
-    if (auto name = parseNameOpt(context))
+    if (std::optional<Name> name = parseNameOpt(context))
         return *name;
 
     // If we have a reserved keyword next at the same line, assume it's an incomplete name
@@ -2379,7 +2390,7 @@ std::pair<AstArray<AstGenericType>, AstArray<AstGenericTypePack>> Parser::parseG
 
                     if (shouldParseTypePackAnnotation(lexer))
                     {
-                        auto typePack = parseTypePackAnnotation();
+                        AstTypePack* typePack = parseTypePackAnnotation();
 
                         namePacks.push_back({name, nameLocation, typePack});
                     }
@@ -2451,7 +2462,7 @@ AstArray<AstTypeOrPack> Parser::parseTypeParams()
         {
             if (shouldParseTypePackAnnotation(lexer))
             {
-                auto typePack = parseTypePackAnnotation();
+                AstTypePack* typePack = parseTypePackAnnotation();
 
                 parameters.push_back({{}, typePack});
             }
@@ -2821,25 +2832,57 @@ AstTypeError* Parser::reportTypeAnnotationError(const Location& location, const
     return allocator.alloc<AstTypeError>(location, types, isMissing, unsigned(parseErrors.size() - 1));
 }
 
-const Lexeme& Parser::nextLexeme()
+void Parser::nextLexeme()
 {
     if (options.captureComments)
     {
-        while (true)
+        if (FFlag::LuauParseAllHotComments)
         {
-            const Lexeme& lexeme = lexer.next(/*skipComments*/ false);
+            Lexeme::Type type = lexer.next(/* skipComments= */ false).type;
-            // Subtlety: Broken comments are weird because we record them as comments AND pass them to the parser as a lexeme.
+
-            // The parser will turn this into a proper syntax error.
+            while (type == Lexeme::BrokenComment || type == Lexeme::Comment || type == Lexeme::BlockComment)
-            if (lexeme.type == Lexeme::BrokenComment)
+            {
+                const Lexeme& lexeme = lexer.current();
                 commentLocations.push_back(Comment{lexeme.type, lexeme.location});
-            if (isComment(lexeme))
+
-                commentLocations.push_back(Comment{lexeme.type, lexeme.location});
+                // Subtlety: Broken comments are weird because we record them as comments AND pass them to the parser as a lexeme.
-            else
+                // The parser will turn this into a proper syntax error.
-                return lexeme;
+                if (lexeme.type == Lexeme::BrokenComment)
+                    return;
+
+                // Comments starting with ! are called "hot comments" and contain directives for type checking / linting
+                if (lexeme.type == Lexeme::Comment && lexeme.length && lexeme.data[0] == '!')
+                {
+                    const char* text = lexeme.data;
+
+                    unsigned int end = lexeme.length;
+                    while (end > 0 && isSpace(text[end - 1]))
+                        --end;
+
+                    hotcomments.push_back({hotcommentHeader, lexeme.location, std::string(text + 1, text + end)});
+                }
+
+                type = lexer.next(/* skipComments= */ false).type;
+            }
+        }
+        else
+        {
+            while (true)
+            {
+                const Lexeme& lexeme = lexer.next(/*skipComments*/ false);
+                // Subtlety: Broken comments are weird because we record them as comments AND pass them to the parser as a lexeme.
+                // The parser will turn this into a proper syntax error.
+                if (lexeme.type == Lexeme::BrokenComment)
+                    commentLocations.push_back(Comment{lexeme.type, lexeme.location});
+                if (isComment(lexeme))
+                    commentLocations.push_back(Comment{lexeme.type, lexeme.location});
+                else
+                    return;
+            }
         }
     }
     else
-        return lexer.next();
+        lexer.next();
 }
 
 } // namespace Luau

Ast/src/TimeTrace.cpp

@@ -9,6 +9,12 @@
 #include <stdlib.h>
 
 #ifdef _WIN32
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif
 #include <Windows.h>
 #endif
 

CLI/FileUtils.cpp

@@ -4,8 +4,13 @@
 #include "Luau/Common.h"
 
 #ifdef _WIN32
+#ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
-#include <windows.h>
+#endif
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif
+#include <Windows.h>
 #else
 #include <dirent.h>
 #include <fcntl.h>

CLI/Repl.cpp

@@ -37,6 +37,8 @@ enum class CompileFormat
     Binary
 };
 
+constexpr int MaxTraversalLimit = 50;
+
 struct GlobalOptions
 {
     int optimizationLevel = 1;
@@ -243,10 +245,115 @@ std::string runCode(lua_State* L, const std::string& source)
     return std::string();
 }
 
+// Replaces the top of the lua stack with the metatable __index for the value
+// if it exists.  Returns true iff __index exists.
+static bool tryReplaceTopWithIndex(lua_State* L)
+{
+    if (luaL_getmetafield(L, -1, "__index"))
+    {
+        // Remove the table leaving __index on the top of stack
+        lua_remove(L, -2);
+        return true;
+    }
+    return false;
+}
+
+
+// This function is similar to lua_gettable, but it avoids calling any
+// lua callback functions (e.g. __index) which might modify the Lua VM state.
+static void safeGetTable(lua_State* L, int tableIndex)
+{
+    lua_pushvalue(L, tableIndex); // Duplicate the table
+
+    // The loop invariant is that the table to search is at -1
+    // and the key is at -2.
+    for (int loopCount = 0;; loopCount++)
+    {
+        lua_pushvalue(L, -2); // Duplicate the key
+        lua_rawget(L, -2);    // Try to find the key
+        if (!lua_isnil(L, -1) || loopCount >= MaxTraversalLimit)
+        {
+            // Either the key has been found, and/or we have reached the max traversal limit
+            break;
+        }
+        else
+        {
+            lua_pop(L, 1); // Pop the nil result
+            if (!luaL_getmetafield(L, -1, "__index"))
+            {
+                lua_pushnil(L);
+                break;
+            }
+            else if (lua_istable(L, -1))
+            {
+                // Replace the current table being searched with __index table
+                lua_replace(L, -2);
+            }
+            else
+            {
+                lua_pop(L, 1); // Pop the value
+                lua_pushnil(L);
+                break;
+            }
+        }
+    }
+
+    lua_remove(L, -2); // Remove the table
+    lua_remove(L, -2); // Remove the original key
+}
+
+// completePartialMatches finds keys that match the specified 'prefix'
+// Note: the table/object to be searched must be on the top of the Lua stack
+static void completePartialMatches(lua_State* L, bool completeOnlyFunctions, const std::string& editBuffer, std::string_view prefix,
+    const AddCompletionCallback& addCompletionCallback)
+{
+    for (int i = 0; i < MaxTraversalLimit && lua_istable(L, -1); i++)
+    {
+        // table, key
+        lua_pushnil(L);
+
+        // Loop over all the keys in the current table
+        while (lua_next(L, -2) != 0)
+        {
+            if (lua_type(L, -2) == LUA_TSTRING)
+            {
+                // table, key, value
+                std::string_view key = lua_tostring(L, -2);
+                int valueType = lua_type(L, -1);
+
+                // If the last separator was a ':' (i.e. a method call) then only functions should be completed.
+                bool requiredValueType = (!completeOnlyFunctions || valueType == LUA_TFUNCTION);
+
+                if (!key.empty() && requiredValueType && Luau::startsWith(key, prefix))
+                {
+                    std::string completedComponent(key.substr(prefix.size()));
+                    std::string completion(editBuffer + completedComponent);
+                    if (valueType == LUA_TFUNCTION)
+                    {
+                        // Add an opening paren for function calls by default.
+                        completion += "(";
+                    }
+                    addCompletionCallback(completion, std::string(key));
+                }
+            }
+            lua_pop(L, 1);
+        }
+
+        // Replace the current table being searched with an __index table if one exists
+        if (!tryReplaceTopWithIndex(L))
+        {
+            break;
+        }
+    }
+}
+
 static void completeIndexer(lua_State* L, const std::string& editBuffer, const AddCompletionCallback& addCompletionCallback)
 {
     std::string_view lookup = editBuffer;
-    char lastSep = 0;
+    bool completeOnlyFunctions = false;
+
+    // Push the global variable table to begin the search
+    lua_pushvalue(L, LUA_GLOBALSINDEX);
 
     for (;;)
     {
@@ -255,60 +362,26 @@ static void completeIndexer(lua_State* L, const std::string& editBuffer, const A
 
         if (sep == std::string_view::npos)
         {
-            // table, key
+            completePartialMatches(L, completeOnlyFunctions, editBuffer, prefix, addCompletionCallback);
-            lua_pushnil(L);
-
-            while (lua_next(L, -2) != 0)
-            {
-                if (lua_type(L, -2) == LUA_TSTRING)
-                {
-                    // table, key, value
-                    std::string_view key = lua_tostring(L, -2);
-                    int valueType = lua_type(L, -1);
-
-                    // If the last separator was a ':' (i.e. a method call) then only functions should be completed.
-                    bool requiredValueType = (lastSep != ':' || valueType == LUA_TFUNCTION);
-
-                    if (!key.empty() && requiredValueType && Luau::startsWith(key, prefix))
-                    {
-                        std::string completedComponent(key.substr(prefix.size()));
-                        std::string completion(editBuffer + completedComponent);
-                        if (valueType == LUA_TFUNCTION)
-                        {
-                            // Add an opening paren for function calls by default.
-                            completion += "(";
-                        }
-                        addCompletionCallback(completion, std::string(key));
-                    }
-                }
-                lua_pop(L, 1);
-            }
-
             break;
         }
         else
         {
             // find the key in the table
             lua_pushlstring(L, prefix.data(), prefix.size());
-            lua_rawget(L, -2);
+            safeGetTable(L, -2);
             lua_remove(L, -2);
 
-            if (lua_type(L, -1) == LUA_TSTRING)
+            if (lua_istable(L, -1) || tryReplaceTopWithIndex(L))
             {
-                // Replace the string object with the string class to perform further lookups of string functions
+                completeOnlyFunctions = lookup[sep] == ':';
-                // Note: We retrieve the string class from _G to prevent issues if the user assigns to `string`.
+                lookup.remove_prefix(sep + 1);
-                lua_pop(L, 1); // Pop the string instance
-                lua_getglobal(L, "_G");
-                lua_pushlstring(L, "string", 6);
-                lua_rawget(L, -2);
-                lua_remove(L, -2); // Remove the global table
-                LUAU_ASSERT(lua_istable(L, -1));
             }
-            else if (!lua_istable(L, -1))
+            else
+            {
+                // Unable to search for keys, so stop searching
                 break;
-
+            }
-            lastSep = lookup[sep];
-            lookup.remove_prefix(sep + 1);
         }
     }
 
@@ -317,12 +390,6 @@ static void completeIndexer(lua_State* L, const std::string& editBuffer, const A
 
 void getCompletions(lua_State* L, const std::string& editBuffer, const AddCompletionCallback& addCompletionCallback)
 {
-    // look the value up in current global table first
-    lua_pushvalue(L, LUA_GLOBALSINDEX);
-    completeIndexer(L, editBuffer, addCompletionCallback);
-
-    // and in actual global table after that
-    lua_getglobal(L, "_G");
     completeIndexer(L, editBuffer, addCompletionCallback);
 }
 
@@ -365,9 +432,7 @@ struct LinenoiseScopedHistory
             ic_set_history(historyFilepath.c_str(), -1 /* default entries (= 200) */);
     }
 
-    ~LinenoiseScopedHistory()
+    ~LinenoiseScopedHistory() {}
-    {
-    }
 
     std::string historyFilepath;
 };

CMakeLists.txt

@@ -104,6 +104,20 @@ if (MSVC AND MSVC_VERSION GREATER_EQUAL 1924)
     set_source_files_properties(VM/src/lvmexecute.cpp PROPERTIES COMPILE_FLAGS /d2ssa-pre-)
 endif()
 
+# embed .natvis inside the library debug information
+if(MSVC)
+    target_link_options(Luau.Ast INTERFACE /NATVIS:${CMAKE_CURRENT_SOURCE_DIR}/tools/natvis/Ast.natvis)
+    target_link_options(Luau.Analysis INTERFACE /NATVIS:${CMAKE_CURRENT_SOURCE_DIR}/tools/natvis/Analysis.natvis)
+    target_link_options(Luau.VM INTERFACE /NATVIS:${CMAKE_CURRENT_SOURCE_DIR}/tools/natvis/VM.natvis)
+endif()
+
+# make .natvis visible inside the solution
+if(MSVC_IDE)
+    target_sources(Luau.Ast PRIVATE tools/natvis/Ast.natvis)
+    target_sources(Luau.Analysis PRIVATE tools/natvis/Analysis.natvis)
+    target_sources(Luau.VM PRIVATE tools/natvis/VM.natvis)
+endif()
+
 if(LUAU_BUILD_CLI)
     target_compile_options(Luau.Repl.CLI PRIVATE ${LUAU_OPTIONS})
     target_compile_options(Luau.Analyze.CLI PRIVATE ${LUAU_OPTIONS})

Sources.cmake

@@ -8,6 +8,7 @@ target_sources(Luau.Ast PRIVATE
     Ast/include/Luau/Location.h
     Ast/include/Luau/ParseOptions.h
     Ast/include/Luau/Parser.h
+    Ast/include/Luau/ParseResult.h
     Ast/include/Luau/StringUtils.h
     Ast/include/Luau/TimeTrace.h
 

VM/src/lapi.cpp

@@ -36,12 +36,9 @@ const char* luau_ident = "$Luau: Copyright (C) 2019-2022 Roblox Corporation $\n"
 static Table* getcurrenv(lua_State* L)
 {
     if (L->ci == L->base_ci)  /* no enclosing function? */
-        return hvalue(gt(L)); /* use global table as environment */
+        return L->gt;         /* use global table as environment */
     else
-    {
+        return curr_func(L)->env;
-        Closure* func = curr_func(L);
-        return func->env;
-    }
 }
 
 static LUAU_NOINLINE TValue* pseudo2addr(lua_State* L, int idx)
@@ -53,11 +50,14 @@ static LUAU_NOINLINE TValue* pseudo2addr(lua_State* L, int idx)
         return registry(L);
     case LUA_ENVIRONINDEX:
     {
-        sethvalue(L, &L->env, getcurrenv(L));
+        sethvalue(L, &L->global->pseudotemp, getcurrenv(L));
-        return &L->env;
+        return &L->global->pseudotemp;
     }
     case LUA_GLOBALSINDEX:
-        return gt(L);
+    {
+        sethvalue(L, &L->global->pseudotemp, L->gt);
+        return &L->global->pseudotemp;
+    }
     default:
     {
         Closure* func = curr_func(L);
@@ -237,6 +237,11 @@ void lua_replace(lua_State* L, int idx)
         func->env = hvalue(L->top - 1);
         luaC_barrier(L, func, L->top - 1);
     }
+    else if (idx == LUA_GLOBALSINDEX)
+    {
+        api_check(L, ttistable(L->top - 1));
+        L->gt = hvalue(L->top - 1);
+    }
     else
     {
         setobj(L, o, L->top - 1);
@@ -783,7 +788,7 @@ void lua_getfenv(lua_State* L, int idx)
         sethvalue(L, L->top, clvalue(o)->env);
         break;
     case LUA_TTHREAD:
-        setobj2s(L, L->top, gt(thvalue(o)));
+        sethvalue(L, L->top, thvalue(o)->gt);
         break;
     default:
         setnilvalue(L->top);
@@ -914,7 +919,7 @@ int lua_setfenv(lua_State* L, int idx)
         clvalue(o)->env = hvalue(L->top - 1);
         break;
     case LUA_TTHREAD:
-        sethvalue(L, gt(thvalue(o)), hvalue(L->top - 1));
+        thvalue(o)->gt = hvalue(L->top - 1);
         break;
     default:
         res = 0;

VM/src/ldebug.cpp

@@ -419,7 +419,7 @@ static void getcoverage(Proto* p, int depth, int* buffer, size_t size, void* con
     }
 
     const char* debugname = p->debugname ? getstr(p->debugname) : NULL;
-    int linedefined = luaG_getline(p, 0);
+    int linedefined = getlinedefined(p);
 
     callback(context, debugname, linedefined, depth, buffer, size);
 

VM/src/ldo.cpp

@@ -17,6 +17,8 @@
 
 #include <string.h>
 
+LUAU_FASTFLAG(LuauReduceStackReallocs)
+
 /*
 ** {======================================================
 ** Error-recovery functions
@@ -164,13 +166,14 @@ static void correctstack(lua_State* L, TValue* oldstack)
 void luaD_reallocstack(lua_State* L, int newsize)
 {
     TValue* oldstack = L->stack;
-    int realsize = newsize + 1 + EXTRA_STACK;
+    int realsize = newsize + (FFlag::LuauReduceStackReallocs ? EXTRA_STACK : 1 + EXTRA_STACK);
-    LUAU_ASSERT(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
+    LUAU_ASSERT(L->stack_last - L->stack == L->stacksize - (FFlag::LuauReduceStackReallocs ? EXTRA_STACK : 1 + EXTRA_STACK));
     luaM_reallocarray(L, L->stack, L->stacksize, realsize, TValue, L->memcat);
+    TValue* newstack = L->stack;
     for (int i = L->stacksize; i < realsize; i++)
-        setnilvalue(L->stack + i); /* erase new segment */
+        setnilvalue(newstack + i); /* erase new segment */
     L->stacksize = realsize;
-    L->stack_last = L->stack + newsize;
+    L->stack_last = newstack + newsize;
     correctstack(L, oldstack);
 }
 
@@ -512,7 +515,7 @@ static void callerrfunc(lua_State* L, void* ud)
 
 static void restore_stack_limit(lua_State* L)
 {
-    LUAU_ASSERT(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
+    LUAU_ASSERT(L->stack_last - L->stack == L->stacksize - (FFlag::LuauReduceStackReallocs ? EXTRA_STACK : 1 + EXTRA_STACK));
     if (L->size_ci > LUAI_MAXCALLS)
     { /* there was an overflow? */
         int inuse = cast_int(L->ci - L->base_ci);

VM/src/ldo.h

@@ -11,7 +11,7 @@
     if ((char*)L->stack_last - (char*)L->top <= (n) * (int)sizeof(TValue)) \
         luaD_growstack(L, n); \
     else \
-        condhardstacktests(luaD_reallocstack(L, L->stacksize - EXTRA_STACK - 1));
+        condhardstacktests(luaD_reallocstack(L, L->stacksize - (FFlag::LuauReduceStackReallocs ? EXTRA_STACK : 1 + EXTRA_STACK)));
 
 #define incr_top(L) \
     { \

VM/src/lgc.cpp

@@ -268,7 +268,7 @@ static void traverseclosure(global_State* g, Closure* cl)
 
 static void traversestack(global_State* g, lua_State* l, bool clearstack)
 {
-    markvalue(g, gt(l));
+    markobject(g, l->gt);
     if (l->namecall)
         stringmark(l->namecall);
     for (StkId o = l->stack; o < l->top; o++)
@@ -643,7 +643,7 @@ static void markroot(lua_State* L)
     g->weak = NULL;
     markobject(g, g->mainthread);
     /* make global table be traversed before main stack */
-    markvalue(g, gt(g->mainthread));
+    markobject(g, g->mainthread->gt);
     markvalue(g, registry(L));
     markmt(g);
     g->gcstate = GCSpropagate;

VM/src/lgc.h

@@ -77,7 +77,7 @@
 
 #define luaC_checkGC(L) \
     { \
-        condhardstacktests(luaD_reallocstack(L, L->stacksize - EXTRA_STACK - 1)); \
+        condhardstacktests(luaD_reallocstack(L, L->stacksize - (FFlag::LuauReduceStackReallocs ? EXTRA_STACK : 1 + EXTRA_STACK))); \
         if (L->global->totalbytes >= L->global->GCthreshold) \
         { \
             condhardmemtests(luaC_validate(L), 1); \

VM/src/lgcdebug.cpp

@@ -88,7 +88,7 @@ static void validateclosure(global_State* g, Closure* cl)
 
 static void validatestack(global_State* g, lua_State* l)
 {
-    validateref(g, obj2gco(l), gt(l));
+    validateobjref(g, obj2gco(l), obj2gco(l->gt));
 
     for (CallInfo* ci = l->base_ci; ci <= l->ci; ++ci)
     {
@@ -370,6 +370,7 @@ static void dumpclosure(FILE* f, Closure* cl)
 
     fprintf(f, ",\"env\":");
     dumpref(f, obj2gco(cl->env));
+
     if (cl->isC)
     {
         if (cl->nupvalues)
@@ -411,11 +412,8 @@ static void dumpthread(FILE* f, lua_State* th)
 
     fprintf(f, "{\"type\":\"thread\",\"cat\":%d,\"size\":%d", th->memcat, int(size));
 
-    if (iscollectable(&th->l_gt))
+    fprintf(f, ",\"env\":");
-    {
+    dumpref(f, obj2gco(th->gt));
-        fprintf(f, ",\"env\":");
-        dumpref(f, gcvalue(&th->l_gt));
-    }
 
     Closure* tcl = 0;
     for (CallInfo* ci = th->base_ci; ci <= th->ci; ++ci)

VM/src/lperf.cpp

@@ -3,6 +3,12 @@
 #include "lua.h"
 
 #ifdef _WIN32
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif
 #include <Windows.h>
 #endif
 

VM/src/lstate.cpp

@@ -11,6 +11,7 @@
 #include "ldebug.h"
 
 LUAU_FASTFLAG(LuauGcPagedSweep)
+LUAU_FASTFLAGVARIABLE(LuauReduceStackReallocs, false)
 
 /*
 ** Main thread combines a thread state and the global state
@@ -31,10 +32,11 @@ static void stack_init(lua_State* L1, lua_State* L)
     /* initialize stack array */
     L1->stack = luaM_newarray(L, BASIC_STACK_SIZE + EXTRA_STACK, TValue, L1->memcat);
     L1->stacksize = BASIC_STACK_SIZE + EXTRA_STACK;
+    TValue* stack = L1->stack;
     for (int i = 0; i < BASIC_STACK_SIZE + EXTRA_STACK; i++)
-        setnilvalue(L1->stack + i); /* erase new stack */
+        setnilvalue(stack + i); /* erase new stack */
-    L1->top = L1->stack;
+    L1->top = stack;
-    L1->stack_last = L1->stack + (L1->stacksize - EXTRA_STACK) - 1;
+    L1->stack_last = stack + (L1->stacksize - (FFlag::LuauReduceStackReallocs ? EXTRA_STACK : 1 + EXTRA_STACK));
     /* initialize first ci */
     L1->ci->func = L1->top;
     setnilvalue(L1->top++); /* `function' entry for this `ci' */
@@ -55,7 +57,7 @@ static void f_luaopen(lua_State* L, void* ud)
 {
     global_State* g = L->global;
     stack_init(L, L);                             /* init stack */
-    sethvalue(L, gt(L), luaH_new(L, 0, 2));       /* table of globals */
+    L->gt = luaH_new(L, 0, 2);                    /* table of globals */
     sethvalue(L, registry(L), luaH_new(L, 0, 2)); /* registry */
     luaS_resize(L, LUA_MINSTRTABSIZE);            /* initial size of string table */
     luaT_init(L);
@@ -69,6 +71,7 @@ static void preinit_state(lua_State* L, global_State* g)
     L->global = g;
     L->stack = NULL;
     L->stacksize = 0;
+    L->gt = NULL;
     L->openupval = NULL;
     L->size_ci = 0;
     L->nCcalls = L->baseCcalls = 0;
@@ -80,7 +83,6 @@ static void preinit_state(lua_State* L, global_State* g)
     L->stackstate = 0;
     L->activememcat = 0;
     L->userdata = NULL;
-    setnilvalue(gt(L));
 }
 
 static void close_state(lua_State* L)
@@ -116,7 +118,7 @@ lua_State* luaE_newthread(lua_State* L)
     preinit_state(L1, L->global);
     L1->activememcat = L->activememcat; // inherit the active memory category
     stack_init(L1, L);                  /* init stack */
-    setobj2n(L, gt(L1), gt(L));         /* share table of globals */
+    L1->gt = L->gt;                     /* share table of globals */
     L1->singlestep = L->singlestep;
     LUAU_ASSERT(iswhite(obj2gco(L1)));
     return L1;
@@ -144,14 +146,30 @@ void lua_resetthread(lua_State* L)
     ci->top = ci->base + LUA_MINSTACK;
     setnilvalue(ci->func);
     L->ci = ci;
-    luaD_reallocCI(L, BASIC_CI_SIZE);
+    if (FFlag::LuauReduceStackReallocs)
+    {
+        if (L->size_ci != BASIC_CI_SIZE)
+            luaD_reallocCI(L, BASIC_CI_SIZE);
+    }
+    else
+    {
+        luaD_reallocCI(L, BASIC_CI_SIZE);
+    }
     /* clear thread state */
     L->status = LUA_OK;
     L->base = L->ci->base;
     L->top = L->ci->base;
     L->nCcalls = L->baseCcalls = 0;
     /* clear thread stack */
-    luaD_reallocstack(L, BASIC_STACK_SIZE);
+    if (FFlag::LuauReduceStackReallocs)
+    {
+        if (L->stacksize != BASIC_STACK_SIZE + EXTRA_STACK)
+            luaD_reallocstack(L, BASIC_STACK_SIZE);
+    }
+    else
+    {
+        luaD_reallocstack(L, BASIC_STACK_SIZE);
+    }
     for (int i = 0; i < L->stacksize; i++)
         setnilvalue(L->stack + i);
 }
@@ -193,6 +211,7 @@ lua_State* lua_newstate(lua_Alloc f, void* ud)
     g->strt.size = 0;
     g->strt.nuse = 0;
     g->strt.hash = NULL;
+    setnilvalue(&g->pseudotemp);
     setnilvalue(registry(L));
     g->gcstate = GCSpause;
     if (!FFlag::LuauGcPagedSweep)

VM/src/lstate.h

@@ -5,9 +5,6 @@
 #include "lobject.h"
 #include "ltm.h"
 
-/* table of globals */
-#define gt(L) (&L->l_gt)
-
 /* registry */
 #define registry(L) (&L->global->registry)
 
@@ -177,6 +174,8 @@ typedef struct global_State
     TString* ttname[LUA_T_COUNT];       /* names for basic types */
     TString* tmname[TM_N];             /* array with tag-method names */
 
+    TValue pseudotemp; /* storage for temporary values used in pseudo2addr */
+
     TValue registry; /* registry table, used by lua_ref and LUA_REGISTRYINDEX */
     int registryfree; /* next free slot in registry */
 
@@ -231,8 +230,7 @@ struct lua_State
     int cachedslot;    /* when table operations or INDEX/NEWINDEX is invoked from Luau, what is the expected slot for lookup? */
 
 
-    TValue l_gt;            /* table of globals */
+    Table* gt;           /* table of globals */
-    TValue env;             /* temporary place for environments */
     UpVal* openupval;    /* list of open upvalues in this stack */
     GCObject* gclist;
 

VM/src/lvmexecute.cpp

@@ -39,7 +39,7 @@
 
 // When calling luau_callTM, we usually push the arguments to the top of the stack.
 // This is safe to do for complicated reasons:
-// - stack guarantees 1 + EXTRA_STACK room beyond stack_last (see luaD_reallocstack)
+// - stack guarantees EXTRA_STACK room beyond stack_last (see luaD_reallocstack)
 // - stack reallocation copies values past stack_last
 
 // All external function calls that can cause stack realloc or Lua calls have to be wrapped in VM_PROTECT

VM/src/lvmload.cpp

@@ -116,12 +116,12 @@ static void resolveImportSafe(lua_State* L, Table* env, TValue* k, uint32_t id)
             // note: we call getimport with nil propagation which means that accesses to table chains like A.B.C will resolve in nil
             // this is technically not necessary but it reduces the number of exceptions when loading scripts that rely on getfenv/setfenv for global
             // injection
-            luaV_getimport(L, hvalue(gt(L)), self->k, self->id, /* propagatenil= */ true);
+            luaV_getimport(L, L->gt, self->k, self->id, /* propagatenil= */ true);
         }
     };
 
     ResolveImport ri = {k, id};
-    if (hvalue(gt(L))->safeenv)
+    if (L->gt->safeenv)
     {
         // luaD_pcall will make sure that if any C/Lua calls during import resolution fail, the thread state is restored back
         int oldTop = lua_gettop(L);
@@ -171,7 +171,7 @@ int luau_load(lua_State* L, const char* chunkname, const char* data, size_t size
     L->global->GCthreshold = SIZE_MAX;
 
     // env is 0 for current environment and a stack index otherwise
-    Table* envt = (env == 0) ? hvalue(gt(L)) : hvalue(luaA_toobject(L, env));
+    Table* envt = (env == 0) ? L->gt : hvalue(luaA_toobject(L, env));
 
     TString* source = luaS_new(L, chunkname);
 

VM/src/lvmutils.cpp

@@ -55,7 +55,7 @@ static void callTMres(lua_State* L, StkId res, const TValue* f, const TValue* p1
 {
     ptrdiff_t result = savestack(L, res);
     // using stack room beyond top is technically safe here, but for very complicated reasons:
-    // * The stack guarantees 1 + EXTRA_STACK room beyond stack_last (see luaD_reallocstack) will be allocated
+    // * The stack guarantees EXTRA_STACK room beyond stack_last (see luaD_reallocstack) will be allocated
     // * we cannot move luaD_checkstack above because the arguments are *sometimes* pointers to the lua
     // stack and checkstack may invalidate those pointers
     // * we cannot use savestack/restorestack because the arguments are sometimes on the C++ stack
@@ -76,7 +76,7 @@ static void callTMres(lua_State* L, StkId res, const TValue* f, const TValue* p1
 static void callTM(lua_State* L, const TValue* f, const TValue* p1, const TValue* p2, const TValue* p3)
 {
     // using stack room beyond top is technically safe here, but for very complicated reasons:
-    // * The stack guarantees 1 + EXTRA_STACK room beyond stack_last (see luaD_reallocstack) will be allocated
+    // * The stack guarantees EXTRA_STACK room beyond stack_last (see luaD_reallocstack) will be allocated
     // * we cannot move luaD_checkstack above because the arguments are *sometimes* pointers to the lua
     // stack and checkstack may invalidate those pointers
     // * we cannot use savestack/restorestack because the arguments are sometimes on the C++ stack

docs/_pages/lint.md

@@ -317,3 +317,13 @@ The code above can be rewritten as follows to avoid the warning and the associat
 ```lua
 local x = if flag then false else true
 ```
+
+## CommentDirective (26)
+
+Luau uses comments that start from `!` to control certain aspects of analysis, for example setting type checking mode via `--!strict` or disabling individual lints with `--!nolint`. Unknown directives are ignored, for example `--!nostrict` doesn't have any effect on the type checking process as the correct spelling is `--!nonstrict`. This warning flags comment directives that are ignored during processing:
+
+```lua
+--!nostrict
+-- Unknown comment directive 'nostrict'; did you mean 'nonstrict'?"
+```
+```

fuzz/linter.cpp

@@ -32,7 +32,7 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* Data, size_t Size)
         Luau::LintOptions lintOptions;
         lintOptions.warningMask = ~0ull;
 
-        Luau::lint(parseResult.root, names, typeck.globalScope, nullptr, lintOptions);
+        Luau::lint(parseResult.root, names, typeck.globalScope, nullptr, {}, lintOptions);
     }
 
     return 0;

fuzz/proto.cpp

@@ -227,7 +227,7 @@ DEFINE_PROTO_FUZZER(const luau::StatBlock& message)
         if (kFuzzLinter)
         {
             Luau::LintOptions lintOptions = {~0u};
-            Luau::lint(parseResult.root, names, sharedEnv.globalScope, module.get(), lintOptions);
+            Luau::lint(parseResult.root, names, sharedEnv.globalScope, module.get(), {}, lintOptions);
         }
     }
 

prototyping/.gitignore

@@ -2,7 +2,11 @@
 *.agdai
 Main
 MAlonzo
-PrettyPrinter
-.ghc.*
-Interpreter
 Examples
+PrettyPrinter
+Interpreter
+Properties
+!Tests/Interpreter
+!Tests/PrettyPrinter
+.ghc.*
+test-failures/

prototyping/README.md

@@ -25,3 +25,21 @@ and run!
 ```
   luau-ast Examples/SmokeTest.lua | ./PrettyPrinter
 ```
+
+## Testing
+
+We have a series of snapshot tests in the `Tests/` directory. You interact with the tests using the `tests` Python script in the `prototyping` directory. To simply run the tests, run:
+
+```sh
+tests --luau-cli ../build/luau-ast --build
+```
+
+This will build the test targets and run them. Run `tests --help` for information about all the command-line options.
+
+### Adding a new test
+
+To add a new test, add it to `Tests/{SUITE_NAME}/{CASE_NAME}`. You'll need an `in.lua` file and an `out.txt` file. The `in.lua` file is the input Luau source code, while the `out.txt` file is the expected output after running `luau-ast in.lua | test_executable`.
+
+### Updating a test
+
+If you make a change to the prototype that results in an expected change in behavior, you might want to update the test cases automatically. To do this, run `tests` with the `--accept-new-output` (`-a` for short) flag. Rather than diffing the output, this will overwrite the `out.txt` files for each test case with the actual result. Commit the resulting changes with your PR.

prototyping/Tests/Interpreter/return_nil/in.lua

@@ -0,0 +1,5 @@
+local function foo(x)
+	return nil
+end
+
+return foo(nil)

prototyping/Tests/Interpreter/return_nil/out.txt

@@ -0,0 +1 @@
+nil

prototyping/Tests/PrettyPrinter/smoke_test/in.lua

@@ -1,12 +1,12 @@
 local function id(x)
-  return x
+	return x
 end
 local function comp(f)
-  return function(g)
+	return function(g)
-    return function(x)
+		return function(x)
-      return f(g(x))
+			return f(g(x))
-    end
+		end
-  end
+	end
 end
 local id2 = comp(id)(id)
 local nil2 = id2(nil)

prototyping/tests.py

@@ -0,0 +1,197 @@
+#!/usr/bin/python
+
+import argparse
+import difflib
+import enum
+import os
+import os.path
+import subprocess
+import sys
+
+SUITES = ["interpreter", "prettyprinter"]
+IN_FILE_NAME = "in.lua"
+OUT_FILE_NAME = "out.txt"
+SUITE_EXE_NAMES = {
+    "interpreter": "Interpreter",
+    "prettyprinter": "PrettyPrinter",
+}
+
+SUITE_ENTRY_POINTS = {
+    "interpreter": "Interpreter.agda",
+    "prettyprinter": "PrettyPrinter.agda",
+}
+
+SUITE_ROOTS = {
+    "interpreter": "Tests/Interpreter",
+    "prettyprinter": "Tests/PrettyPrinter",
+}
+
+class TestResultStatus(enum.Enum):
+    CLI_ERROR = 0
+    EXE_ERROR = 1
+    DIFF_ERROR = 2
+    SUCCESS = 3
+    WROTE_NEW = 4
+
+class DiffFailure:
+    def __init__(self, expected, actual):
+        self.expected = expected
+        self.actual = actual
+    
+    def diff_text(self):
+        diff_generator = difflib.context_diff(self.expected.splitlines(), self.actual.splitlines(), fromfile="expected", tofile="actual", n=3)
+        return "".join(diff_generator)
+    
+    def diff_html(self):
+        differ = difflib.HtmlDiff(tabsize=4)
+        return differ.make_file(self.expected.splitlines(), self.actual.splitlines(), fromdesc="Expected", todesc="Actual", context=True, numlines=5)
+
+class TestCaseResult:
+    def __init__(self, suite, case, status, details):
+        self.suite = suite
+        self.case = case
+        self.status = status
+        self.details = details
+    
+    def did_pass(self):
+        return self.status == TestResultStatus.SUCCESS or self.status == TestResultStatus.WROTE_NEW
+    
+    def to_string(self):
+        prefix = f"[{self.suite}/{self.case}]: "
+        if self.status == TestResultStatus.CLI_ERROR:
+            return f"{prefix}CLI ERROR: {self.details}"
+        elif self.status == TestResultStatus.EXE_ERROR:
+            return f"{prefix}EXE ERROR: {self.details}"
+        elif self.status == TestResultStatus.DIFF_ERROR:
+            text_diff = self.details.diff_text()
+            return f"{prefix}FAILED:\n{text_diff}"
+        elif self.status == TestResultStatus.SUCCESS:
+            return f"{prefix}SUCCEEDED"
+        elif self.status == TestResultStatus.WROTE_NEW:
+            return f"{prefix}WROTE NEW RESULT"
+    
+    def write_artifact(self, artifact_root):
+        if self.status != TestResultStatus.DIFF_ERROR:
+            return
+
+        filename = f"{self.suite}-{self.case}.out.html"
+        path = os.path.join(artifact_root, filename)
+        html = self.details.diff_html()
+        with open(path, "w") as file:
+            file.write(html)
+
+parser = argparse.ArgumentParser(description="Runs prototype test cases")
+parser.add_argument("--luau-cli", "-l", dest="cli_location", required=True, help="The location of luau-cli")
+parser.add_argument("--root", "-r", dest="prototype_root", required=False, default=os.getcwd(), help="The root of the prototype")
+parser.add_argument("--build", "-b", dest="build", action="store_true", default=True, help="Whether to automatically build required test binaries")
+parser.add_argument("--suite", "-s", dest="suites", action="append", default=[], choices=SUITES, help="Which test suites to run")
+parser.add_argument("--case", "-c", dest="cases", action="append", default=[], help="Which test cases to run")
+parser.add_argument("--accept-new-output", "-a", dest="snapshot", action="store_true", default=False, help="Whether to write the new output to files, instead of diffing against it")
+parser.add_argument("--write-diff-failures", dest="write_diffs", action="store_true", default=False, help="Whether to write test failure diffs to files")
+parser.add_argument("--diff-failure-location", dest="diff_location", default=None, help="Where to write diff failure files to")
+
+def build_suite(root, suite):
+    entry_point = SUITE_ENTRY_POINTS.get(suite)
+    if entry_point is None:
+        return (False, "Invalid suite")
+    
+    result = subprocess.run(["~/.cabal/bin/agda", "--compile", entry_point], shell=True, cwd=root, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+    if result.returncode == 0:
+        return (True, None)
+    else:
+        return (False, result.stdout)
+
+def run_test(in_path, out_path, cli_path, exe_path, snapshot):
+    cli_result = subprocess.run([cli_path, in_path], capture_output=True)
+    if cli_result.returncode != 0:
+        return (TestResultStatus.CLI_ERROR, f"CLI error: {cli_result.stderr}")
+    
+    exe_result = subprocess.run(exe_path, input=cli_result.stdout, capture_output=True)
+    if exe_result.returncode != 0:
+        return (TestResultStatus.EXE_ERROR, f"Executable error; stdout:{exe_result.stdout}\n\nstderr: {exe_result.stderr}")
+    actual_result = exe_result.stdout.decode("utf-8")
+
+    if snapshot:
+        with open(out_path, "w") as out_file:
+            out_file.write(actual_result)
+            return (TestResultStatus.WROTE_NEW, None)
+    else:
+        with open(out_path, "r") as out_file:
+            expected_result = out_file.read()
+
+            if expected_result != actual_result:
+                return (TestResultStatus.DIFF_ERROR, DiffFailure(expected_result, actual_result))
+    
+    return (TestResultStatus.SUCCESS, None)
+
+def should_run_case(case_name, filters):
+    if len(filters) == 0:
+        return True
+
+    return any([f in case_name for f in filters])
+
+def run_test_suite(args, suite, suite_root, suite_exe):
+    results = []
+
+    for entry in os.listdir(suite_root):
+        if not should_run_case(entry, args.cases):
+            continue
+
+        case_path = os.path.join(suite_root, entry)
+        if os.path.isdir(case_path):
+            in_path = os.path.join(case_path, IN_FILE_NAME)
+            out_path = os.path.join(case_path, OUT_FILE_NAME)
+
+            if not os.path.exists(in_path) or not os.path.exists(out_path):
+                continue
+            
+            status, details = run_test(in_path, out_path, args.cli_location, suite_exe, args.snapshot)
+            result = TestCaseResult(suite, entry, status, details)
+            results.append(result)
+
+    return results
+
+def main():
+    args = parser.parse_args()
+
+    suites = args.suites if len(args.suites) > 0 else SUITES
+    root = os.path.abspath(args.prototype_root)
+
+    if args.build:
+        for suite in suites:
+            success, reason = build_suite(root, suite)
+
+            if not success:
+                print(f"Error building executable for test suite {suite}:\n{reason}")
+                sys.exit(1)
+            else:
+                print(f"Built executable for test suite {suite} successfully.")
+    
+    failed = False
+    for suite in suites:
+        suite_root = os.path.join(root, SUITE_ROOTS.get(suite))
+        suite_exe = os.path.join(root, SUITE_EXE_NAMES.get(suite))
+        print(f"Running test suite {suite}...")
+        results = run_test_suite(args, suite, suite_root, suite_exe)
+
+        passed = 0
+        total = len(results)
+
+        for result in results:
+            if result.did_pass():
+                passed += 1
+            else:
+                failed = True
+
+        print(f"Suite {suite} [{passed} / {total} passed]:")
+        for result in results:
+            print(result.to_string())
+
+            if args.write_diffs:
+                result.write_artifact(args.diff_location)
+    
+    if failed:
+        sys.exit(1)
+
+if __name__ == "__main__":
+    main()

rfcs/STATUS.md

@@ -0,0 +1,52 @@
+This document tracks unimplemented RFCs.
+
+## Deprecate getfenv/setfenv
+
+[RFC: Deprecate getfenv/setfenv](https://github.com/Roblox/luau/blob/master/rfcs/deprecate-getfenv-setfenv.md)
+
+**Status**: Needs implementation.
+
+**Notes**: Implementing this RFC triggers warnings across the board in the apps ecosystem, in particular in testing libraries. Pending code changes / decisions.
+
+## Read-only and write-only properties
+
+[RFC: Read-only properties](https://github.com/Roblox/luau/blob/master/rfcs/property-readonly.md) |
+[RFC: Write-only properties](https://github.com/Roblox/luau/blob/master/rfcs/property-writeonly.md)
+
+**Status**: Needs implementation
+
+## Sealed/unsealed typing changes
+
+[RFC: Sealed table subtyping](https://github.com/Roblox/luau/blob/master/rfcs/sealed-table-subtyping.md) |
+[RFC: Unsealed table literals](https://github.com/Roblox/luau/blob/master/rfcs/unsealed-table-literals.md) |
+[RFC: Only strip optional properties from unsealed tables during subtyping](https://github.com/Roblox/luau/blob/master/rfcs/unsealed-table-subtyping-strips-optional-properties.md)
+
+**Status**: Implemented but depends on new transaction log implementation that is not fully live yet.
+
+## Nil-forgiving operator
+
+[RFC: nil-forgiving postfix operator !](https://github.com/Roblox/luau/blob/master/rfcs/syntax-nil-forgiving-operator.md)
+
+**Status**: Needs implementation.
+
+**Notes**: Do we need to reevaluate the necessity given `assert` and improved refinements?
+
+## Safe navigation operator
+
+[RFC: Safe navigation postfix operator (?)](https://github.com/Roblox/luau/blob/master/rfcs/syntax-safe-navigation-operator.md)
+
+**Status**: Needs implementation.
+
+**Notes**: We have unresolved issues with interaction between this feature and Roblox instance hierarchy. This may affect the viability of this proposal.
+
+## String interpolation
+
+[RFC: String interpolation](https://github.com/Roblox/luau/blob/master/rfcs/syntax-string-interpolation.md)
+
+**Status**: Needs implementation
+
+## Generalized iteration
+
+[RFC: Generalized iteration](https://github.com/Roblox/luau/blob/master/rfcs/generalized-iteration.md)
+
+**Status**: Needs implementation

rfcs/syntax-default-type-alias-type-parameters.md

@@ -1,5 +1,7 @@
 # Default type alias type parameters
 
+**Status**: Implemented
+
 ## Summary
 
 Introduce syntax to provide default type values inside the type alias type parameter list.

rfcs/syntax-singleton-types.md

@@ -2,6 +2,8 @@
 
 > Note: this RFC was adapted from an internal proposal that predates RFC process
 
+**Status**: Implemented
+
 ## Summary
 
 Introduce a new kind of type variable, called singleton types. They are just like normal types but has the capability to represent a constant runtime value as a type.

tests/Autocomplete.test.cpp

@@ -1,7 +1,6 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #include "Luau/Autocomplete.h"
 #include "Luau/BuiltinDefinitions.h"
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"
 #include "Luau/VisitTypeVar.h"
@@ -2610,6 +2609,27 @@ a = if temp then even elseif true then temp else e@9
     CHECK(ac.entryMap.count("elseif") == 0);
 }
 
+TEST_CASE_FIXTURE(ACFixture, "autocomplete_if_else_regression")
+{
+    ScopedFastFlag FFlagLuauIfElseExprFixCompletionIssue("LuauIfElseExprFixCompletionIssue", true);
+    check(R"(
+local abcdef = 0;
+local temp = false
+local even = true;
+local a
+a = if temp then even else@1
+a = if temp then even else @2
+a = if temp then even else abc@3
+        )");
+
+    auto ac = autocomplete('1');
+    CHECK(ac.entryMap.count("else") == 0);
+    ac = autocomplete('2');
+    CHECK(ac.entryMap.count("else") == 0);
+    ac = autocomplete('3');
+    CHECK(ac.entryMap.count("abcdef"));
+}
+
 TEST_CASE_FIXTURE(ACFixture, "autocomplete_explicit_type_pack")
 {
     check(R"(

tests/Compiler.test.cpp

@@ -10,6 +10,11 @@
 #include <sstream>
 #include <string_view>
 
+namespace Luau
+{
+std::string rep(const std::string& s, size_t n);
+}
+
 using namespace Luau;
 
 static std::string compileFunction(const char* source, uint32_t id)
@@ -1960,15 +1965,6 @@ RETURN R8 -1
 )");
 }
 
-static std::string rep(const std::string& s, size_t n)
-{
-    std::string r;
-    r.reserve(s.length() * n);
-    for (size_t i = 0; i < n; ++i)
-        r += s;
-    return r;
-}
-
 TEST_CASE("RecursionParse")
 {
     // The test forcibly pushes the stack limit during compilation; in NoOpt, the stack consumption is much larger so we need to reduce the limit to

tests/Conformance.test.cpp

@@ -492,6 +492,8 @@ TEST_CASE("DateTime")
 
 TEST_CASE("Debug")
 {
+    ScopedFastFlag luauTableFieldFunctionDebugname{"LuauTableFieldFunctionDebugname", true};
+
     runConformance("debug.lua");
 }
 
@@ -890,6 +892,12 @@ TEST_CASE("Coverage")
                         lua_pushstring(L, function);
                         lua_setfield(L, -2, "name");
 
+                        lua_pushinteger(L, linedefined);
+                        lua_setfield(L, -2, "linedefined");
+
+                        lua_pushinteger(L, depth);
+                        lua_setfield(L, -2, "depth");
+
                         for (size_t i = 0; i < size; ++i)
                             if (hits[i] != -1)
                             {

tests/Fixture.cpp

@@ -2,6 +2,7 @@
 #include "Fixture.h"
 
 #include "Luau/AstQuery.h"
+#include "Luau/Parser.h"
 #include "Luau/TypeVar.h"
 #include "Luau/TypeAttach.h"
 #include "Luau/Transpiler.h"
@@ -112,7 +113,7 @@ AstStatBlock* Fixture::parse(const std::string& source, const ParseOptions& pars
     sourceModule->name = fromString(mainModuleName);
     sourceModule->root = result.root;
     sourceModule->mode = parseMode(result.hotcomments);
-    sourceModule->ignoreLints = LintWarning::parseMask(result.hotcomments);
+    sourceModule->hotcomments = std::move(result.hotcomments);
 
     if (!result.errors.empty())
     {
@@ -157,6 +158,7 @@ CheckResult Fixture::check(const std::string& source)
 LintResult Fixture::lint(const std::string& source, const std::optional<LintOptions>& lintOptions)
 {
     ParseOptions parseOptions;
+    parseOptions.captureComments = true;
     configResolver.defaultConfig.mode = Mode::Nonstrict;
     parse(source, parseOptions);
 

tests/Fixture.h

@@ -8,7 +8,6 @@
 #include "Luau/Linter.h"
 #include "Luau/Location.h"
 #include "Luau/ModuleResolver.h"
-#include "Luau/Parser.h"
 #include "Luau/ToString.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"

tests/Frontend.test.cpp

@@ -2,7 +2,6 @@
 #include "Luau/AstQuery.h"
 #include "Luau/BuiltinDefinitions.h"
 #include "Luau/Frontend.h"
-#include "Luau/Parser.h"
 #include "Luau/RequireTracer.h"
 
 #include "Fixture.h"
@@ -897,8 +896,6 @@ TEST_CASE_FIXTURE(FrontendFixture, "clearStats")
 
 TEST_CASE_FIXTURE(FrontendFixture, "typecheck_twice_for_ast_types")
 {
-    ScopedFastFlag sffs("LuauTypeCheckTwice", true);
-
     fileResolver.source["Module/A"] = R"(
         local a = 1
     )";

tests/Linter.test.cpp

@@ -1395,12 +1395,10 @@ TEST_CASE_FIXTURE(Fixture, "DeprecatedApi")
 
     TypeId colorType = typeChecker.globalTypes.addType(TableTypeVar{{}, std::nullopt, typeChecker.globalScope->level, Luau::TableState::Sealed});
 
-    getMutable<TableTypeVar>(colorType)->props = {
+    getMutable<TableTypeVar>(colorType)->props = {{"toHSV", {typeChecker.anyType, /* deprecated= */ true, "Color3:ToHSV"}}};
-        {"toHSV", {typeChecker.anyType, /* deprecated= */ true, "Color3:ToHSV"} }
-    };
 
     addGlobalBinding(typeChecker, "Color3", Binding{colorType, {}});
- 
+
     freeze(typeChecker.globalTypes);
 
     LintResult result = lintTyped(R"(
@@ -1554,8 +1552,46 @@ _ = (math.random() < 0.5 and false) or 42 -- currently ignored
 )");
 
     REQUIRE_EQ(result.warnings.size(), 2);
-    CHECK_EQ(result.warnings[0].text, "The and-or expression always evaluates to the second alternative because the first alternative is false; consider using if-then-else expression instead");
+    CHECK_EQ(result.warnings[0].text, "The and-or expression always evaluates to the second alternative because the first alternative is false; "
-    CHECK_EQ(result.warnings[1].text, "The and-or expression always evaluates to the second alternative because the first alternative is nil; consider using if-then-else expression instead");
+                                      "consider using if-then-else expression instead");
+    CHECK_EQ(result.warnings[1].text, "The and-or expression always evaluates to the second alternative because the first alternative is nil; "
+                                      "consider using if-then-else expression instead");
+}
+
+TEST_CASE_FIXTURE(Fixture, "WrongComment")
+{
+    ScopedFastFlag sff("LuauParseAllHotComments", true);
+
+    LintResult result = lint(R"(
+--!strict
+--!struct
+--!nolintGlobal
+--!nolint Global
+--!nolint KnownGlobal
+--!nolint UnknownGlobal
+--! no more lint
+--!strict here
+do end
+--!nolint
+)");
+
+    REQUIRE_EQ(result.warnings.size(), 6);
+    CHECK_EQ(result.warnings[0].text, "Unknown comment directive 'struct'; did you mean 'strict'?");
+    CHECK_EQ(result.warnings[1].text, "Unknown comment directive 'nolintGlobal'");
+    CHECK_EQ(result.warnings[2].text, "nolint directive refers to unknown lint rule 'Global'");
+    CHECK_EQ(result.warnings[3].text, "nolint directive refers to unknown lint rule 'KnownGlobal'; did you mean 'UnknownGlobal'?");
+    CHECK_EQ(result.warnings[4].text, "Comment directive with the type checking mode has extra symbols at the end of the line");
+    CHECK_EQ(result.warnings[5].text, "Comment directive is ignored because it is placed after the first non-comment token");
+}
+
+TEST_CASE_FIXTURE(Fixture, "WrongCommentMuteSelf")
+{
+    LintResult result = lint(R"(
+--!nolint
+--!struct
+)");
+
+    REQUIRE_EQ(result.warnings.size(), 0); // --!nolint disables WrongComment lint :)
 }
 
 TEST_SUITE_END();

tests/NonstrictMode.test.cpp

@@ -1,5 +1,4 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/Parser.h"
 #include "Luau/Scope.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"

tests/Parser.test.cpp

@@ -1,6 +1,5 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #include "Luau/Parser.h"
-#include "Luau/TypeInfer.h"
 
 #include "Fixture.h"
 #include "ScopedFlags.h"
@@ -300,8 +299,9 @@ TEST_CASE_FIXTURE(Fixture, "functions_can_have_return_annotations")
     AstStatFunction* statFunction = block->body.data[0]->as<AstStatFunction>();
     REQUIRE(statFunction != nullptr);
 
-    CHECK_EQ(statFunction->func->returnAnnotation.types.size, 1);
+    REQUIRE(statFunction->func->returnAnnotation.has_value());
-    CHECK(statFunction->func->returnAnnotation.tailType == nullptr);
+    CHECK_EQ(statFunction->func->returnAnnotation->types.size, 1);
+    CHECK(statFunction->func->returnAnnotation->tailType == nullptr);
 }
 
 TEST_CASE_FIXTURE(Fixture, "functions_can_have_a_function_type_annotation")
@@ -316,9 +316,9 @@ TEST_CASE_FIXTURE(Fixture, "functions_can_have_a_function_type_annotation")
     AstStatFunction* statFunc = block->body.data[0]->as<AstStatFunction>();
     REQUIRE(statFunc != nullptr);
 
-    AstArray<AstType*>& retTypes = statFunc->func->returnAnnotation.types;
+    REQUIRE(statFunc->func->returnAnnotation.has_value());
-    REQUIRE(statFunc->func->hasReturnAnnotation);
+    CHECK(statFunc->func->returnAnnotation->tailType == nullptr);
-    CHECK(statFunc->func->returnAnnotation.tailType == nullptr);
+    AstArray<AstType*>& retTypes = statFunc->func->returnAnnotation->types;
     REQUIRE(retTypes.size == 1);
 
     AstTypeFunction* funTy = retTypes.data[0]->as<AstTypeFunction>();
@@ -337,9 +337,9 @@ TEST_CASE_FIXTURE(Fixture, "function_return_type_should_disambiguate_from_functi
     AstStatFunction* statFunc = block->body.data[0]->as<AstStatFunction>();
     REQUIRE(statFunc != nullptr);
 
-    AstArray<AstType*>& retTypes = statFunc->func->returnAnnotation.types;
+    REQUIRE(statFunc->func->returnAnnotation.has_value());
-    REQUIRE(statFunc->func->hasReturnAnnotation);
+    CHECK(statFunc->func->returnAnnotation->tailType == nullptr);
-    CHECK(statFunc->func->returnAnnotation.tailType == nullptr);
+    AstArray<AstType*>& retTypes = statFunc->func->returnAnnotation->types;
     REQUIRE(retTypes.size == 2);
 
     AstTypeReference* ty0 = retTypes.data[0]->as<AstTypeReference>();
@@ -363,9 +363,9 @@ TEST_CASE_FIXTURE(Fixture, "function_return_type_should_parse_as_function_type_a
     AstStatFunction* statFunc = block->body.data[0]->as<AstStatFunction>();
     REQUIRE(statFunc != nullptr);
 
-    AstArray<AstType*>& retTypes = statFunc->func->returnAnnotation.types;
+    REQUIRE(statFunc->func->returnAnnotation.has_value());
-    REQUIRE(statFunc->func->hasReturnAnnotation);
+    CHECK(statFunc->func->returnAnnotation->tailType == nullptr);
-    CHECK(statFunc->func->returnAnnotation.tailType == nullptr);
+    AstArray<AstType*>& retTypes = statFunc->func->returnAnnotation->types;
     REQUIRE(retTypes.size == 1);
 
     AstTypeFunction* funTy = retTypes.data[0]->as<AstTypeFunction>();
@@ -707,12 +707,25 @@ TEST_CASE_FIXTURE(Fixture, "mode_is_unset_if_no_hot_comment")
 
 TEST_CASE_FIXTURE(Fixture, "sense_hot_comment_on_first_line")
 {
-    ParseResult result = parseEx("   --!strict ");
+    ParseOptions options;
+    options.captureComments = true;
+
+    ParseResult result = parseEx("   --!strict ", options);
     std::optional<Mode> mode = parseMode(result.hotcomments);
     REQUIRE(bool(mode));
     CHECK_EQ(int(*mode), int(Mode::Strict));
 }
 
+TEST_CASE_FIXTURE(Fixture, "non_header_hot_comments")
+{
+    ParseOptions options;
+    options.captureComments = true;
+
+    ParseResult result = parseEx("do end --!strict", options);
+    std::optional<Mode> mode = parseMode(result.hotcomments);
+    REQUIRE(!mode);
+}
+
 TEST_CASE_FIXTURE(Fixture, "stop_if_line_ends_with_hyphen")
 {
     CHECK_THROWS_AS(parse("   -"), std::exception);
@@ -720,7 +733,10 @@ TEST_CASE_FIXTURE(Fixture, "stop_if_line_ends_with_hyphen")
 
 TEST_CASE_FIXTURE(Fixture, "nonstrict_mode")
 {
-    ParseResult result = parseEx("--!nonstrict");
+    ParseOptions options;
+    options.captureComments = true;
+
+    ParseResult result = parseEx("--!nonstrict", options);
     CHECK(result.errors.empty());
     std::optional<Mode> mode = parseMode(result.hotcomments);
     REQUIRE(bool(mode));
@@ -729,7 +745,10 @@ TEST_CASE_FIXTURE(Fixture, "nonstrict_mode")
 
 TEST_CASE_FIXTURE(Fixture, "nocheck_mode")
 {
-    ParseResult result = parseEx("--!nocheck");
+    ParseOptions options;
+    options.captureComments = true;
+
+    ParseResult result = parseEx("--!nocheck", options);
     CHECK(result.errors.empty());
     std::optional<Mode> mode = parseMode(result.hotcomments);
     REQUIRE(bool(mode));
@@ -1498,8 +1517,6 @@ return
 
 TEST_CASE_FIXTURE(Fixture, "parse_error_broken_comment")
 {
-    ScopedFastFlag luauStartingBrokenComment{"LuauStartingBrokenComment", true};
-
     const char* expected = "Expected identifier when parsing expression, got unfinished comment";
 
     matchParseError("--[[unfinished work", expected);

tests/Repl.test.cpp

@@ -73,7 +73,7 @@ public:
 private:
     std::unique_ptr<lua_State, void (*)(lua_State*)> luaState;
 
-    // This is a simplicitic and incomplete pretty printer.
+    // This is a simplistic and incomplete pretty printer.
     // It is included here to test that the pretty printer hook is being called.
     // More elaborate tests to ensure correct output can be added if we introduce
     // a more feature rich pretty printer.
@@ -158,12 +158,25 @@ TEST_CASE_FIXTURE(ReplFixture, "CompleteGlobalVariables")
         myvariable1 = 5
         myvariable2 = 5
 )");
-    CompletionSet completions = getCompletionSet("myvar");
+    {
+        // Try to complete globals that are added by the user's script
+        CompletionSet completions = getCompletionSet("myvar");
 
-    std::string prefix = "";
+        std::string prefix = "";
-    CHECK(completions.size() == 2);
+        CHECK(completions.size() == 2);
-    CHECK(checkCompletion(completions, prefix, "myvariable1"));
+        CHECK(checkCompletion(completions, prefix, "myvariable1"));
-    CHECK(checkCompletion(completions, prefix, "myvariable2"));
+        CHECK(checkCompletion(completions, prefix, "myvariable2"));
+    }
+    {
+        // Try completing some builtin functions
+        CompletionSet completions = getCompletionSet("math.m");
+
+        std::string prefix = "math.";
+        CHECK(completions.size() == 3);
+        CHECK(checkCompletion(completions, prefix, "max("));
+        CHECK(checkCompletion(completions, prefix, "min("));
+        CHECK(checkCompletion(completions, prefix, "modf("));
+    }
 }
 
 TEST_CASE_FIXTURE(ReplFixture, "CompleteTableKeys")
@@ -206,4 +219,188 @@ TEST_CASE_FIXTURE(ReplFixture, "StringMethods")
     }
 }
 
+TEST_CASE_FIXTURE(ReplFixture, "TableWithMetatableIndexTable")
+{
+    runCode(L, R"(
+        -- Create 't' which is a table with a metatable with an __index table
+        mt = {}
+        mt.__index = mt
+
+        t = {}
+        setmetatable(t, mt)
+
+        mt.mtkey1 = {x="x value", y="y value", 1, 2}
+        mt.mtkey2 = 2
+
+        t.tkey1 = {data1 = 2, data2 = "str", 3, 4}
+        t.tkey2 = 4
+)");
+    {
+        CompletionSet completions = getCompletionSet("t.t");
+
+        std::string prefix = "t.";
+        CHECK(completions.size() == 2);
+        CHECK(checkCompletion(completions, prefix, "tkey1"));
+        CHECK(checkCompletion(completions, prefix, "tkey2"));
+    }
+    {
+        CompletionSet completions = getCompletionSet("t.tkey1.data2:re");
+
+        std::string prefix = "t.tkey1.data2:";
+        CHECK(completions.size() == 2);
+        CHECK(checkCompletion(completions, prefix, "rep("));
+        CHECK(checkCompletion(completions, prefix, "reverse("));
+    }
+    {
+        CompletionSet completions = getCompletionSet("t.mtk");
+
+        std::string prefix = "t.";
+        CHECK(completions.size() == 2);
+        CHECK(checkCompletion(completions, prefix, "mtkey1"));
+        CHECK(checkCompletion(completions, prefix, "mtkey2"));
+    }
+    {
+        CompletionSet completions = getCompletionSet("t.mtkey1.");
+
+        std::string prefix = "t.mtkey1.";
+        CHECK(completions.size() == 2);
+        CHECK(checkCompletion(completions, prefix, "x"));
+        CHECK(checkCompletion(completions, prefix, "y"));
+    }
+}
+
+TEST_CASE_FIXTURE(ReplFixture, "TableWithMetatableIndexFunction")
+{
+    runCode(L, R"(
+        -- Create 't' which is a table with a metatable with an __index function
+        mt = {}
+        mt.__index = function(table, key)
+            print("mt.__index called")
+            if key == "foo" then
+                return "FOO"
+            elseif key == "bar" then
+                return "BAR"
+            else
+                return nil
+            end
+        end
+
+        t = {}
+        setmetatable(t, mt)
+        t.tkey = 0
+)");
+    {
+        CompletionSet completions = getCompletionSet("t.t");
+
+        std::string prefix = "t.";
+        CHECK(completions.size() == 1);
+        CHECK(checkCompletion(completions, prefix, "tkey"));
+    }
+    {
+        // t.foo is a valid key, but should not be completed because it requires calling an __index function
+        CompletionSet completions = getCompletionSet("t.foo");
+
+        CHECK(completions.size() == 0);
+    }
+    {
+        // t.foo is a valid key, but should not be found because it requires calling an __index function
+        CompletionSet completions = getCompletionSet("t.foo:");
+
+        CHECK(completions.size() == 0);
+    }
+}
+
+TEST_CASE_FIXTURE(ReplFixture, "TableWithMultipleMetatableIndexTables")
+{
+    runCode(L, R"(
+        -- Create a table with a chain of metatables
+        mt2 = {}
+        mt2.__index = mt2
+
+        mt = {}
+        mt.__index = mt
+        setmetatable(mt, mt2)
+
+        t = {}
+        setmetatable(t, mt)
+
+        mt2.mt2key = {x=1, y=2}
+        mt.mtkey = 2
+        t.tkey = 3
+)");
+    {
+        CompletionSet completions = getCompletionSet("t.");
+
+        std::string prefix = "t.";
+        CHECK(completions.size() == 4);
+        CHECK(checkCompletion(completions, prefix, "__index"));
+        CHECK(checkCompletion(completions, prefix, "tkey"));
+        CHECK(checkCompletion(completions, prefix, "mtkey"));
+        CHECK(checkCompletion(completions, prefix, "mt2key"));
+    }
+    {
+        CompletionSet completions = getCompletionSet("t.__index.");
+
+        std::string prefix = "t.__index.";
+        CHECK(completions.size() == 3);
+        CHECK(checkCompletion(completions, prefix, "__index"));
+        CHECK(checkCompletion(completions, prefix, "mtkey"));
+        CHECK(checkCompletion(completions, prefix, "mt2key"));
+    }
+    {
+        CompletionSet completions = getCompletionSet("t.mt2key.");
+
+        std::string prefix = "t.mt2key.";
+        CHECK(completions.size() == 2);
+        CHECK(checkCompletion(completions, prefix, "x"));
+        CHECK(checkCompletion(completions, prefix, "y"));
+    }
+}
+
+TEST_CASE_FIXTURE(ReplFixture, "TableWithDeepMetatableIndexTables")
+{
+    runCode(L, R"(
+-- Creates a table with a chain of metatables of length `count`
+function makeChainedTable(count)
+    local result = {}
+    result.__index = result
+    result[string.format("entry%d", count)] = { count = count }
+    if count == 0 then
+        return result
+    else
+        return setmetatable(result, makeChainedTable(count - 1))
+    end
+end
+
+t30 = makeChainedTable(30)
+t60 = makeChainedTable(60)
+)");
+    {
+        // Check if entry0 exists
+        CompletionSet completions = getCompletionSet("t30.entry0");
+
+        std::string prefix = "t30.";
+        CHECK(checkCompletion(completions, prefix, "entry0"));
+    }
+    {
+        // Check if entry0.count exists
+        CompletionSet completions = getCompletionSet("t30.entry0.co");
+
+        std::string prefix = "t30.entry0.";
+        CHECK(checkCompletion(completions, prefix, "count"));
+    }
+    {
+        // Check if entry0 exists.  With the max traversal limit of 50 in the repl, this should fail.
+        CompletionSet completions = getCompletionSet("t60.entry0");
+
+        CHECK(completions.size() == 0);
+    }
+    {
+        // Check if entry0.count exists.  With the max traversal limit of 50 in the repl, this should fail.
+        CompletionSet completions = getCompletionSet("t60.entry0.co");
+
+        CHECK(completions.size() == 0);
+    }
+}
+
 TEST_SUITE_END();

tests/RequireTracer.test.cpp

@@ -1,6 +1,6 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/Parser.h"
 #include "Luau/RequireTracer.h"
+#include "Luau/Parser.h"
 
 #include "Fixture.h"
 

tests/TypeInfer.aliases.test.cpp

@@ -598,15 +598,13 @@ TEST_CASE_FIXTURE(Fixture, "generic_typevars_are_not_considered_to_escape_their_
 /*
  * The two-pass alias definition system starts by ascribing a free TypeVar to each alias.  It then
  * circles back to fill in the actual type later on.
- * 
+ *
  * If this free type is unified with something degenerate like `any`, we need to take extra care
  * to ensure that the alias actually binds to the type that the user expected.
  */
 TEST_CASE_FIXTURE(Fixture, "forward_declared_alias_is_not_clobbered_by_prior_unification_with_any")
 {
-    ScopedFastFlag sff[] = {
+    ScopedFastFlag sff[] = {{"LuauTwoPassAliasDefinitionFix", true}};
-        {"LuauTwoPassAliasDefinitionFix", true}
-    };
 
     CheckResult result = check(R"(
         local function x()

tests/TypeInfer.annotations.test.cpp

@@ -1,6 +1,5 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #include "Luau/BuiltinDefinitions.h"
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"
 

tests/TypeInfer.builtins.test.cpp

@@ -1,5 +1,4 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/BuiltinDefinitions.h"
 

tests/TypeInfer.classes.test.cpp

@@ -1,6 +1,5 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #include "Luau/BuiltinDefinitions.h"
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"
 

tests/TypeInfer.definitions.test.cpp

@@ -1,6 +1,5 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #include "Luau/BuiltinDefinitions.h"
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"
 

tests/TypeInfer.generics.test.cpp

@@ -1,5 +1,4 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"
 

tests/TypeInfer.intersectionTypes.test.cpp

@@ -1,5 +1,4 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"
 

tests/TypeInfer.provisional.test.cpp

@@ -1,5 +1,4 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 
 #include "Fixture.h"

tests/TypeInfer.singletons.test.cpp

@@ -426,8 +426,6 @@ TEST_CASE_FIXTURE(Fixture, "if_then_else_expression_singleton_options")
         {"LuauSingletonTypes", true},
         {"LuauParseSingletonTypes", true},
         {"LuauExpectedTypesOfProperties", true},
-        {"LuauIfElseExpectedType2", true},
-        {"LuauIfElseBranchTypeUnion", true},
     };
 
     CheckResult result = check(R"(

tests/TypeInfer.tables.test.cpp

@@ -1,6 +1,5 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #include "Luau/BuiltinDefinitions.h"
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"
 
@@ -2168,8 +2167,6 @@ b()
 
 TEST_CASE_FIXTURE(Fixture, "length_operator_union")
 {
-    ScopedFastFlag luauLengthOnCompositeType{"LuauLengthOnCompositeType", true};
-
     CheckResult result = check(R"(
 local x: {number} | {string}
 local y = #x
@@ -2180,8 +2177,6 @@ local y = #x
 
 TEST_CASE_FIXTURE(Fixture, "length_operator_intersection")
 {
-    ScopedFastFlag luauLengthOnCompositeType{"LuauLengthOnCompositeType", true};
-
     CheckResult result = check(R"(
 local x: {number} & {z:string} -- mixed tables are evil
 local y = #x
@@ -2192,8 +2187,6 @@ local y = #x
 
 TEST_CASE_FIXTURE(Fixture, "length_operator_non_table_union")
 {
-    ScopedFastFlag luauLengthOnCompositeType{"LuauLengthOnCompositeType", true};
-
     CheckResult result = check(R"(
 local x: {number} | any | string
 local y = #x
@@ -2204,8 +2197,6 @@ local y = #x
 
 TEST_CASE_FIXTURE(Fixture, "length_operator_union_errors")
 {
-    ScopedFastFlag luauLengthOnCompositeType{"LuauLengthOnCompositeType", true};
-
     CheckResult result = check(R"(
 local x: {number} | number | string
 local y = #x
@@ -2214,4 +2205,38 @@ local y = #x
     LUAU_REQUIRE_ERROR_COUNT(1, result);
 }
 
+TEST_CASE_FIXTURE(Fixture, "dont_hang_when_trying_to_look_up_in_cyclic_metatable_index")
+{
+    ScopedFastFlag sff{"LuauTerminateCyclicMetatableIndexLookup", true};
+
+    // t :: t1 where t1 = {metatable {__index: t1, __tostring: (t1) -> string}}
+    CheckResult result = check(R"(
+        local mt = {}
+        local t = setmetatable({}, mt)
+        mt.__index = t
+
+        function mt:__tostring()
+            return t.p
+        end
+    )");
+
+    LUAU_REQUIRE_ERROR_COUNT(1, result);
+    CHECK_EQ("Type 't' does not have key 'p'", toString(result.errors[0]));
+}
+
+TEST_CASE_FIXTURE(Fixture, "give_up_after_one_metatable_index_look_up")
+{
+    CheckResult result = check(R"(
+        local data = { x = 5 }
+        local t1 = setmetatable({}, { __index = data })
+        local t2 = setmetatable({}, t1) -- note: must be t1, not a new table
+
+        local x1 = t1.x -- ok
+        local x2 = t2.x -- nope
+    )");
+
+    LUAU_REQUIRE_ERROR_COUNT(1, result);
+    CHECK_EQ("Type 't2' does not have key 'x'", toString(result.errors[0]));
+}
+
 TEST_SUITE_END();

tests/TypeInfer.test.cpp

@@ -2,7 +2,6 @@
 
 #include "Luau/AstQuery.h"
 #include "Luau/BuiltinDefinitions.h"
-#include "Luau/Parser.h"
 #include "Luau/Scope.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"
@@ -4654,8 +4653,6 @@ a = setmetatable(a, { __call = function(x) end })
 
 TEST_CASE_FIXTURE(Fixture, "infer_through_group_expr")
 {
-    ScopedFastFlag luauGroupExpectedType{"LuauGroupExpectedType", true};
-
     CheckResult result = check(R"(
 local function f(a: (number, number) -> number) return a(1, 3) end
 f(((function(a, b) return a + b end)))
@@ -4735,21 +4732,14 @@ local a = if false then "a" elseif false then "b" else "c"
 
 TEST_CASE_FIXTURE(Fixture, "tc_if_else_expressions_type_union")
 {
-    ScopedFastFlag sff3{"LuauIfElseBranchTypeUnion", true};
+    CheckResult result = check(R"(local a: number? = if true then 42 else nil)");
 
-    {
+    LUAU_REQUIRE_NO_ERRORS(result);
-        CheckResult result = check(R"(local a: number? = if true then 42 else nil)");
+    CHECK_EQ(toString(requireType("a"), {true}), "number?");
-
-        LUAU_REQUIRE_NO_ERRORS(result);
-        CHECK_EQ(toString(requireType("a"), {true}), "number?");
-    }
 }
 
 TEST_CASE_FIXTURE(Fixture, "tc_if_else_expressions_expected_type_1")
 {
-    ScopedFastFlag luauIfElseExpectedType2{"LuauIfElseExpectedType2", true};
-    ScopedFastFlag luauIfElseBranchTypeUnion{"LuauIfElseBranchTypeUnion", true};
-
     CheckResult result = check(R"(
 type X = {number | string}
 local a: X = if true then {"1", 2, 3} else {4, 5, 6}
@@ -4761,9 +4751,6 @@ local a: X = if true then {"1", 2, 3} else {4, 5, 6}
 
 TEST_CASE_FIXTURE(Fixture, "tc_if_else_expressions_expected_type_2")
 {
-    ScopedFastFlag luauIfElseExpectedType2{"LuauIfElseExpectedType2", true};
-    ScopedFastFlag luauIfElseBranchTypeUnion{"LuauIfElseBranchTypeUnion", true};
-
     CheckResult result = check(R"(
 local a: number? = if true then 1 else nil
 )");
@@ -4773,8 +4760,6 @@ local a: number? = if true then 1 else nil
 
 TEST_CASE_FIXTURE(Fixture, "tc_if_else_expressions_expected_type_3")
 {
-    ScopedFastFlag luauIfElseExpectedType2{"LuauIfElseExpectedType2", true};
-
     CheckResult result = check(R"(
 local function times<T>(n: any, f: () -> T)
     local result: {T} = {}
@@ -5058,8 +5043,6 @@ end
 
 TEST_CASE_FIXTURE(Fixture, "recursive_metatable_crash")
 {
-    ScopedFastFlag luauMetatableAreEqualRecursion{"LuauMetatableAreEqualRecursion", true};
-
     CheckResult result = check(R"(
 local function getIt()
     local y
@@ -5076,8 +5059,6 @@ local c = a or b
 
 TEST_CASE_FIXTURE(Fixture, "bound_typepack_promote")
 {
-    ScopedFastFlag luauCommittingTxnLogFreeTpPromote{"LuauCommittingTxnLogFreeTpPromote", true};
-
     // No assertions should trigger
     check(R"(
 local function p()
@@ -5251,7 +5232,6 @@ TEST_CASE_FIXTURE(Fixture, "taking_the_length_of_string_singleton")
         {"LuauDiscriminableUnions2", true},
         {"LuauRefactorTypeVarQuestions", true},
         {"LuauSingletonTypes", true},
-        {"LuauLengthOnCompositeType", true},
     };
 
     CheckResult result = check(R"(
@@ -5272,7 +5252,6 @@ TEST_CASE_FIXTURE(Fixture, "taking_the_length_of_union_of_string_singleton")
         {"LuauDiscriminableUnions2", true},
         {"LuauRefactorTypeVarQuestions", true},
         {"LuauSingletonTypes", true},
-        {"LuauLengthOnCompositeType", true},
     };
 
     CheckResult result = check(R"(

tests/TypeInfer.tryUnify.test.cpp

@@ -1,5 +1,4 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/Parser.h"
 #include "Luau/Scope.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"

tests/TypeInfer.typePacks.cpp

@@ -1,6 +1,5 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 #include "Luau/BuiltinDefinitions.h"
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"
 
@@ -930,8 +929,6 @@ type R = { m: F<R> }
 
 TEST_CASE_FIXTURE(Fixture, "pack_tail_unification_check")
 {
-    ScopedFastFlag luauUnifyPackTails{"LuauUnifyPackTails", true};
-
     CheckResult result = check(R"(
 local a: () -> (number, ...string)
 local b: () -> (number, ...boolean)

tests/TypeInfer.unionTypes.test.cpp

@@ -1,5 +1,4 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"
 

tests/TypePack.test.cpp

@@ -1,5 +1,4 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/Parser.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"
 

tests/TypeVar.test.cpp

@@ -1,5 +1,4 @@
 // This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
-#include "Luau/Parser.h"
 #include "Luau/Scope.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/TypeVar.h"

tests/conformance/coroutine.lua

@@ -371,6 +371,15 @@ do
   st, msg = coroutine.close(co)
   assert(st and msg == nil)
   assert(f() == 42)
+
+  -- closing a coroutine with a large stack
+  co = coroutine.create(function()
+    local function f(depth) return if depth > 0 then f(depth - 1) + depth else 0 end
+    coroutine.yield(f(100))
+  end)
+  assert(coroutine.resume(co))
+  st, msg = coroutine.close(co)
+  assert(st and msg == nil)
 end
 
 return 'OK'

tests/conformance/coverage.lua

@@ -49,16 +49,24 @@ foo()
 c = getcoverage(foo)
 assert(#c == 1)
 assert(c[1].name == "foo")
+assert(c[1].linedefined == 4)
+assert(c[1].depth == 0)
 assert(validate(c[1], {5, 6, 7}, {}))
 
 bar()
 c = getcoverage(bar)
 assert(#c == 3)
 assert(c[1].name == "bar")
+assert(c[1].linedefined == 10)
+assert(c[1].depth == 0)
 assert(validate(c[1], {11, 15, 19}, {}))
 assert(c[2].name == "one")
+assert(c[2].linedefined == 11)
+assert(c[2].depth == 1)
 assert(validate(c[2], {12}, {}))
 assert(c[3].name == nil)
+assert(c[3].linedefined == 15)
+assert(c[3].depth == 1)
 assert(validate(c[3], {}, {16}))
 
 return 'OK'

tests/conformance/debug.lua

@@ -76,6 +76,9 @@ assert(baz(co, 2, "n") == nil)
 assert(baz(math.sqrt, "n") == "sqrt")
 assert(baz(math.sqrt, "f") == math.sqrt) -- yes this is pointless
 
+local t = { foo = function() return 1 end }
+assert(baz(t.foo, "n") == "foo")
+
 -- info multi-arg returns
 function quux(...)
 	return {debug.info(...)}

tests/main.cpp

@@ -10,6 +10,9 @@
 #ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
 #endif
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif
 #include <Windows.h> // IsDebuggerPresent
 #endif
 
@@ -52,7 +55,7 @@ static bool debuggerPresent()
 #endif
 }
 
-static int assertionHandler(const char* expr, const char* file, int line, const char* function)
+static int testAssertionHandler(const char* expr, const char* file, int line, const char* function)
 {
     if (debuggerPresent())
         LUAU_DEBUGBREAK();
@@ -218,7 +221,7 @@ static void setFastFlags(const std::vector<doctest::String>& flags)
 
 int main(int argc, char** argv)
 {
-    Luau::assertHandler() = assertionHandler;
+    Luau::assertHandler() = testAssertionHandler;
 
     doctest::registerReporter<BoostLikeReporter>("boost", 0, true);
 

tools/natvis/Analysis.natvis

@@ -0,0 +1,78 @@
+<?xml version="1.0" encoding="utf-8"?>
+<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
+
+  <Type Name="Luau::AnyTypeVar">
+    <DisplayString>AnyTypeVar</DisplayString>
+  </Type>
+
+  <Type Name="Luau::Variant&lt;*&gt;">
+    <DisplayString Condition="typeId == 0" Optional="true">{{ index=0, value={*($T1*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 1" Optional="true">{{ index=1, value={*($T2*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 2" Optional="true">{{ index=2, value={*($T3*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 3" Optional="true">{{ index=3, value={*($T4*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 4" Optional="true">{{ index=4, value={*($T5*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 5" Optional="true">{{ index=5, value={*($T6*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 6" Optional="true">{{ index=6, value={*($T7*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 7" Optional="true">{{ index=7, value={*($T8*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 8" Optional="true">{{ index=8, value={*($T9*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 9" Optional="true">{{ index=9, value={*($T10*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 10" Optional="true">{{ index=10, value={*($T11*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 11" Optional="true">{{ index=11, value={*($T12*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 12" Optional="true">{{ index=12, value={*($T13*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 13" Optional="true">{{ index=13, value={*($T14*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 14" Optional="true">{{ index=14, value={*($T15*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 15" Optional="true">{{ index=15, value={*($T16*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 16" Optional="true">{{ index=16, value={*($T17*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 17" Optional="true">{{ index=17, value={*($T18*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 18" Optional="true">{{ index=18, value={*($T19*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 19" Optional="true">{{ index=19, value={*($T20*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 20" Optional="true">{{ index=20, value={*($T21*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 21" Optional="true">{{ index=21, value={*($T22*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 22" Optional="true">{{ index=22, value={*($T23*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 23" Optional="true">{{ index=23, value={*($T24*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 24" Optional="true">{{ index=24, value={*($T25*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 25" Optional="true">{{ index=25, value={*($T26*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 26" Optional="true">{{ index=26, value={*($T27*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 27" Optional="true">{{ index=27, value={*($T28*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 28" Optional="true">{{ index=28, value={*($T29*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 29" Optional="true">{{ index=29, value={*($T30*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 30" Optional="true">{{ index=30, value={*($T31*)storage} }}</DisplayString>
+    <DisplayString Condition="typeId == 31" Optional="true">{{ index=31, value={*($T32*)storage} }}</DisplayString>
+    <Expand>
+      <Item Name="index">typeId</Item>
+      <Item Name="[value]" Condition="typeId == 0" Optional="true">*($T1*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 1" Optional="true">*($T2*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 2" Optional="true">*($T3*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 3" Optional="true">*($T4*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 4" Optional="true">*($T5*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 5" Optional="true">*($T6*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 6" Optional="true">*($T7*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 7" Optional="true">*($T8*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 8" Optional="true">*($T9*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 9" Optional="true">*($T10*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 10" Optional="true">*($T11*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 11" Optional="true">*($T12*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 12" Optional="true">*($T13*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 13" Optional="true">*($T14*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 14" Optional="true">*($T15*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 15" Optional="true">*($T16*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 16" Optional="true">*($T17*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 17" Optional="true">*($T18*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 18" Optional="true">*($T19*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 19" Optional="true">*($T20*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 20" Optional="true">*($T21*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 21" Optional="true">*($T22*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 22" Optional="true">*($T23*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 23" Optional="true">*($T24*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 24" Optional="true">*($T25*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 25" Optional="true">*($T26*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 26" Optional="true">*($T27*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 27" Optional="true">*($T28*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 28" Optional="true">*($T29*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 29" Optional="true">*($T30*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 30" Optional="true">*($T31*)storage</Item>
+      <Item Name="[value]" Condition="typeId == 31" Optional="true">*($T32*)storage</Item>
+    </Expand>
+  </Type>
+
+</AutoVisualizer>

tools/natvis/Ast.natvis

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?>
+<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
+
+  <Type Name="Luau::AstArray&lt;*&gt;">
+    <DisplayString>AstArray size={size}</DisplayString>
+    <Expand>
+      <Item Name="[size]">size</Item>
+      <ArrayItems>
+        <Size>size</Size>
+        <ValuePointer>data</ValuePointer>
+      </ArrayItems>
+    </Expand>
+  </Type>
+
+  <Type Name="Luau::TempVector&lt;*&gt;">
+    <Expand>
+      <Item Name="[size]">size_</Item>
+      <ArrayItems>
+        <Size>size_</Size>
+        <ValuePointer>storage._Mypair._Myval2._Myfirst + offset</ValuePointer>
+      </ArrayItems>
+    </Expand>
+  </Type>
+
+</AutoVisualizer>

tools/natvis/VM.natvis

@@ -0,0 +1,269 @@
+<?xml version="1.0" encoding="utf-8"?>
+<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
+
+  <Type Name="::lua_TValue">
+    <DisplayString Condition="tt == lua_Type::LUA_TNIL">nil</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TBOOLEAN">{(bool)value.b}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TLIGHTUSERDATA">lightuserdata {value.p}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TNUMBER">number = {value.n}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TVECTOR">vector = {value.v[0]}, {value.v[1]}, {*(float*)&amp;extra}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TSTRING">{value.gc->ts}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TTABLE">{value.gc->h}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TFUNCTION">function {value.gc->cl,view(short)}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TUSERDATA">userdata {value.gc->u}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TTHREAD">thread {value.gc->th}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TPROTO">proto {value.gc->p}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TUPVAL">upvalue {value.gc->uv}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TDEADKEY">deadkey</DisplayString>
+    <DisplayString>empty</DisplayString>
+    <Expand>
+      <Item Name="[lightuserdata]" Condition="tt == lua_Type::LUA_TLIGHTUSERDATA">value.p</Item>
+      <Item Name="[string]" Condition="tt == lua_Type::LUA_TSTRING">value.gc->ts</Item>
+      <Item Name="[table]" Condition="tt == lua_Type::LUA_TTABLE">value.gc->h</Item>
+      <Item Name="[C function]" Condition="tt == lua_Type::LUA_TFUNCTION &amp;&amp; value.gc-&gt;cl.isC">value.gc->cl</Item>
+      <Item Name="[Lua function]" Condition="tt == lua_Type::LUA_TFUNCTION &amp;&amp; !value.gc-&gt;cl.isC">value.gc->cl</Item>
+      <Item Name="[userdata]" Condition="tt == lua_Type::LUA_TUSERDATA">value.gc->u</Item>
+      <Item Name="[thread]" Condition="tt == lua_Type::LUA_TTHREAD">value.gc->th</Item>
+      <Item Name="[proto]" Condition="tt == lua_Type::LUA_TPROTO">value.gc->p</Item>
+      <Item Name="[upvalue]" Condition="tt == lua_Type::LUA_TUPVAL">value.gc->uv</Item>
+      <Synthetic Name="[gc]" Condition="tt >= lua_Type::LUA_TSTRING">
+        <DisplayString Condition="value.gc-&gt;gch.marked &amp; 8">fixed ({(int)value.gc-&gt;gch.marked})</DisplayString>
+        <DisplayString Condition="value.gc-&gt;gch.marked &amp; 4">black ({(int)value.gc-&gt;gch.marked})</DisplayString>
+        <DisplayString Condition="value.gc-&gt;gch.marked &amp; 1">white ({(int)value.gc-&gt;gch.marked})</DisplayString>
+        <DisplayString Condition="value.gc-&gt;gch.marked &amp; 2">white ({(int)value.gc-&gt;gch.marked})</DisplayString>
+        <DisplayString Condition="(value.gc-&gt;gch.marked &amp; 3) == 0">gray ({(int)value.gc-&gt;gch.marked})</DisplayString>
+      </Synthetic>
+    </Expand>
+  </Type>
+
+  <Type Name="::TKey">
+    <DisplayString Condition="tt == lua_Type::LUA_TNIL">nil</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TBOOLEAN">{(bool)value.b}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TLIGHTUSERDATA">lightuserdata {value.p}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TNUMBER">number = {value.n}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TVECTOR">vector = {value.v[0]}, {value.v[1]}, {*(float*)&amp;extra}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TSTRING">{value.gc->ts}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TTABLE">{value.gc->h}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TFUNCTION">function {value.gc->cl,view(short)}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TUSERDATA">userdata {value.gc->u}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TTHREAD">thread {value.gc->th}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TPROTO">proto {value.gc->p}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TUPVAL">upvalue {value.gc->uv}</DisplayString>
+    <DisplayString Condition="tt == lua_Type::LUA_TDEADKEY">deadkey</DisplayString>
+    <DisplayString>empty</DisplayString>
+    <Expand>
+      <Item Name="[lightuserdata]" Condition="tt == lua_Type::LUA_TLIGHTUSERDATA">(void**)value.p</Item>
+      <Item Name="[string]" Condition="tt == lua_Type::LUA_TSTRING">value.gc->ts</Item>
+      <Item Name="[table]" Condition="tt == lua_Type::LUA_TTABLE">value.gc->h</Item>
+      <Item Name="[C function]" Condition="tt == lua_Type::LUA_TFUNCTION &amp;&amp; value.gc-&gt;cl.isC">value.gc->cl</Item>
+      <Item Name="[Lua function]" Condition="tt == lua_Type::LUA_TFUNCTION &amp;&amp; !value.gc-&gt;cl.isC">value.gc->cl</Item>
+      <Item Name="[userdata]" Condition="tt == lua_Type::LUA_TUSERDATA">value.gc->u</Item>
+      <Item Name="[thread]" Condition="tt == lua_Type::LUA_TTHREAD">value.gc->th</Item>
+      <Item Name="[proto]" Condition="tt == lua_Type::LUA_TPROTO">value.gc->p</Item>
+      <Item Name="[upvalue]" Condition="tt == lua_Type::LUA_TUPVAL">value.gc->uv</Item>
+
+      <Item Name="[next]">next</Item>
+    </Expand>
+  </Type>
+
+  <Type Name="::LuaNode">
+    <DisplayString Condition="key.tt != lua_Type::LUA_TNIL || val.tt != lua_Type::LUA_TNIL">{key,na} = {val}</DisplayString>
+    <DisplayString Condition="key.tt == lua_Type::LUA_TNIL &amp;&amp; val.tt == 0">---</DisplayString>
+  </Type>
+
+  <Type Name="::Table">
+    <DisplayString>table</DisplayString>
+    <Expand>
+      <Item Name="metatable" Condition="metatable">metatable</Item>
+
+      <Synthetic Name="hash">
+        <DisplayString>[size] {1&lt;&lt;lsizenode}</DisplayString>
+        <Expand>
+          <IndexListItems>
+            <Size>1&lt;&lt;lsizenode</Size>
+            <ValueNode>node[$i]</ValueNode>
+          </IndexListItems>
+        </Expand>
+      </Synthetic>
+      <Synthetic Name="array">
+        <DisplayString>[size] {sizearray}</DisplayString>
+        <Expand>
+          <IndexListItems>
+            <Size>sizearray</Size>
+            <ValueNode>array[$i]</ValueNode>
+          </IndexListItems>
+        </Expand>
+      </Synthetic>
+    </Expand>
+  </Type>
+
+  <Type Name="::Udata">
+    <Expand>
+      <CustomListItems>
+        <Variable Name="count" InitialValue="1&lt;&lt;metatable->lsizenode" />
+        <Variable Name="i" InitialValue="0" />
+
+        <Size>1</Size>
+        <Loop>
+          <Break Condition="i &gt;= count" />
+          <If Condition="metatable->node[i].key.tt == lua_Type::LUA_TSTRING">
+            <If Condition="strcmp(metatable-&gt;node[i].key.value.gc->ts.data, &quot;__type&quot;) == 0">
+              <Item Name="[type]">metatable-&gt;node[i].val</Item>
+            <Break/>
+            </If>
+          </If>
+          <Exec>i = i + 1</Exec>
+        </Loop>
+        <If Condition="i == count">
+          <Item Name="[type]">"unknown",sb</Item>
+        </If>
+      </CustomListItems>
+      <Item Name="tag">tag</Item>
+      <Item Name="len">len</Item>
+      <Item Name="metatable">metatable</Item>
+      <Item Name="data">data</Item>
+    </Expand>
+  </Type>
+
+  <Type Name="::Closure">
+    <DisplayString Condition="isC == 1" IncludeView="short">{c.f,na}</DisplayString>
+    <DisplayString Condition="isC == 0" IncludeView="short">{l.p,na}</DisplayString>
+    <DisplayString Condition="isC == 1" ExcludeView="short">{c}</DisplayString>
+    <DisplayString Condition="isC == 0" ExcludeView="short">{l}</DisplayString>
+    <DisplayString>invalid</DisplayString>
+  </Type>
+
+  <Type Name="::TString">
+    <DisplayString>{data,s}</DisplayString>
+  </Type>
+
+  <Type Name ="::lua_State">
+    <DisplayString Condition="ci-&gt;func-&gt;value.gc-&gt;cl.isC">
+      {ci-&gt;func-&gt;value.gc-&gt;cl.c.f,na}
+    </DisplayString>
+    <DisplayString Condition="!ci-&gt;func-&gt;value.gc-&gt;cl.isC &amp;&amp; ci-&gt;func-&gt;value.gc-&gt;cl.l.p-&gt;debugname" Optional="true">
+      {ci-&gt;func-&gt;value.gc-&gt;cl.l.p-&gt;source-&gt;data,sb}:{ci-&gt;func-&gt;value.gc-&gt;cl.l.p-&gt;linedefined,d} {ci-&gt;func-&gt;value.gc-&gt;cl.l.p-&gt;debugname->data,sb}
+    </DisplayString>
+    <DisplayString Condition="!ci-&gt;func-&gt;value.gc-&gt;cl.isC" Optional="true">
+      {ci-&gt;func-&gt;value.gc-&gt;cl.l.p-&gt;source-&gt;data,sb}:{ci-&gt;func-&gt;value.gc-&gt;cl.l.p-&gt;linedefined,d}
+    </DisplayString>
+    <DisplayString>thread</DisplayString>
+    <Expand>
+      <Synthetic Name="[call stack]">
+        <DisplayString>{ci-base_ci} frames</DisplayString>
+        <Expand>
+          <IndexListItems>
+            <Size>ci-base_ci</Size>
+            <!-- the +1 is omitted here to avoid some issues with a blank call -->
+            <ValueNode>
+              base_ci[ci-base_ci - $i].func-&gt;value.gc-&gt;cl,view(short)
+            </ValueNode>
+          </IndexListItems>
+        </Expand>
+      </Synthetic>
+      <Synthetic Name="[top frame stack]">
+        <DisplayString>{top-base} values</DisplayString>
+        <Expand>
+          <ArrayItems>
+            <Size>top-base</Size>
+            <ValuePointer>base</ValuePointer>
+          </ArrayItems>
+        </Expand>
+      </Synthetic>
+      <Synthetic Name="[stack]">
+        <DisplayString>{top-stack} values</DisplayString>
+        <Expand>
+          <ArrayItems>
+            <Size>top-stack</Size>
+            <ValuePointer>stack</ValuePointer>
+          </ArrayItems>
+        </Expand>
+      </Synthetic>
+      <Synthetic Name="[open upvals]" Condition="openupval != 0">
+        <Expand>
+          <LinkedListItems>
+            <HeadPointer>openupval</HeadPointer>
+            <NextPointer>u.l.next</NextPointer>
+            <ValueNode>this</ValueNode>
+          </LinkedListItems>
+        </Expand>
+      </Synthetic>
+      <Item Name="l_gt">l_gt</Item>
+      <Item Name="env">env</Item>
+      <Item Name="userdata">userdata</Item>
+    </Expand>
+  </Type>
+
+  <Type Name="::Proto">
+    <DisplayString Condition="debugname">{source->data,sb}:{linedefined} function {debugname->data,sb} [{(int)numparams} arg, {(int)nups} upval]</DisplayString>
+    <DisplayString Condition="!debugname">{source->data,sb}:{linedefined} [{(int)numparams} arg, {(int)nups} upval]</DisplayString>
+    <Expand>
+      <Item Name="debugname">debugname</Item>
+      <Synthetic Name="[constants]">
+        <DisplayString>constants</DisplayString>
+        <Expand>
+          <IndexListItems>
+            <Size>sizek</Size>
+            <ValueNode>k[$i]</ValueNode>
+          </IndexListItems>
+        </Expand>
+      </Synthetic>
+      <Synthetic Name="[locals]">
+        <DisplayString>locals</DisplayString>
+        <Expand>
+          <IndexListItems>
+            <Size>sizelocvars</Size>
+            <ValueNode>locvars[$i]</ValueNode>
+          </IndexListItems>
+        </Expand>
+      </Synthetic>
+      <Synthetic Name="[bytecode]">
+        <DisplayString>bytecode</DisplayString>
+        <Expand>
+          <IndexListItems>
+            <Size>sizecode</Size>
+            <ValueNode>code[$i]</ValueNode>
+          </IndexListItems>
+        </Expand>
+      </Synthetic>
+      <Synthetic Name="[functions]">
+        <DisplayString>functions</DisplayString>
+        <Expand>
+          <IndexListItems>
+            <Size>sizep</Size>
+            <ValueNode>p[$i]</ValueNode>
+          </IndexListItems>
+        </Expand>
+      </Synthetic>
+      <Synthetic Name="[upvals]">
+        <DisplayString>upvals</DisplayString>
+        <Expand>
+          <IndexListItems>
+            <Size>sizeupvalues</Size>
+            <ValueNode>upvalues[$i]</ValueNode>
+          </IndexListItems>
+        </Expand>
+      </Synthetic>
+
+      <Item Name="source">source</Item>
+    </Expand>
+  </Type>
+
+  <Type Name="::GCheader">
+    <Expand>
+      <Synthetic Name="[type]">
+        <DisplayString>{(lua_Type)tt}</DisplayString>
+      </Synthetic>
+      <Synthetic Name="[gc]">
+        <DisplayString Condition="marked &amp; 8">fixed ({(int)marked})</DisplayString>
+        <DisplayString Condition="marked &amp; 4">black ({(int)marked})</DisplayString>
+        <DisplayString Condition="marked &amp; 1">white ({(int)marked})</DisplayString>
+        <DisplayString Condition="marked &amp; 2">white ({(int)marked})</DisplayString>
+        <DisplayString Condition="(marked &amp; 3) == 0">gray ({(int)marked})</DisplayString>
+        <DisplayString>unknown</DisplayString>
+      </Synthetic>
+      <Item Name="memcat">memcat</Item>
+    </Expand>
+  </Type>
+
+</AutoVisualizer>