luau/Analysis/include/Luau/ConstraintSolver.h
Alexander McCord daf79328fc
Sync to upstream/release/628 (#1278)
### What's new?

* Remove a case of unsound `table.move` optimization
* Add Luau stack slot reservations that were missing in REPL (fixes
#1273)

### New Type Solver

* Assignments have been completely reworked to fix a case of cyclic
constraint dependency
* When indexing, if the fresh type's upper bound already contains a
compatible indexer, do not add another upper bound
* Distribute type arguments over all type families sans `eq`, `keyof`,
`rawkeyof`, and other internal type families
* Fix a case where `buffers` component weren't read in two places (fixes
#1267)
* Fix a case where things that constitutes a strong ref were slightly
incorrect
* Fix a case where constraint dependencies weren't setup wrt `for ...
in` statement

### Native Codegen

* Fix an optimization that splits TValue store only when its value and
its tag are compatible
* Implement a system to plug additional type information for custom host
userdata types

---

### Internal Contributors

Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Alexander McCord <amccord@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>

---------

Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Vighnesh <vvijay@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: David Cope <dcope@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
2024-05-31 12:18:18 -07:00

352 lines
15 KiB
C++

// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
#pragma once
#include "Luau/Constraint.h"
#include "Luau/DenseHash.h"
#include "Luau/Error.h"
#include "Luau/Location.h"
#include "Luau/Module.h"
#include "Luau/Normalize.h"
#include "Luau/Substitution.h"
#include "Luau/ToString.h"
#include "Luau/Type.h"
#include "Luau/TypeCheckLimits.h"
#include "Luau/TypeFwd.h"
#include "Luau/Variant.h"
#include <utility>
#include <vector>
namespace Luau
{
enum class ValueContext;
struct DcrLogger;
class AstExpr;
// TypeId, TypePackId, or Constraint*. It is impossible to know which, but we
// never dereference this pointer.
using BlockedConstraintId = Variant<TypeId, TypePackId, const Constraint*>;
struct HashBlockedConstraintId
{
size_t operator()(const BlockedConstraintId& bci) const;
};
struct ModuleResolver;
struct InstantiationSignature
{
TypeFun fn;
std::vector<TypeId> arguments;
std::vector<TypePackId> packArguments;
bool operator==(const InstantiationSignature& rhs) const;
bool operator!=(const InstantiationSignature& rhs) const
{
return !((*this) == rhs);
}
};
struct HashInstantiationSignature
{
size_t operator()(const InstantiationSignature& signature) const;
};
struct ConstraintSolver
{
NotNull<TypeArena> arena;
NotNull<BuiltinTypes> builtinTypes;
InternalErrorReporter iceReporter;
NotNull<Normalizer> normalizer;
// The entire set of constraints that the solver is trying to resolve.
std::vector<NotNull<Constraint>> constraints;
NotNull<Scope> rootScope;
ModuleName currentModuleName;
// Constraints that the solver has generated, rather than sourcing from the
// scope tree.
std::vector<std::unique_ptr<Constraint>> solverConstraints;
// This includes every constraint that has not been fully solved.
// A constraint can be both blocked and unsolved, for instance.
std::vector<NotNull<const Constraint>> unsolvedConstraints;
// A mapping of constraint pointer to how many things the constraint is
// blocked on. Can be empty or 0 for constraints that are not blocked on
// anything.
std::unordered_map<NotNull<const Constraint>, size_t> blockedConstraints;
// A mapping of type/pack pointers to the constraints they block.
std::unordered_map<BlockedConstraintId, DenseHashSet<const Constraint*>, HashBlockedConstraintId> blocked;
// Memoized instantiations of type aliases.
DenseHashMap<InstantiationSignature, TypeId, HashInstantiationSignature> instantiatedAliases{{}};
// Breadcrumbs for where a free type's upper bound was expanded. We use
// these to provide more helpful error messages when a free type is solved
// as never unexpectedly.
DenseHashMap<TypeId, std::vector<std::pair<Location, TypeId>>> upperBoundContributors{nullptr};
// A mapping from free types to the number of unresolved constraints that mention them.
DenseHashMap<TypeId, size_t> unresolvedConstraints{{}};
// Irreducible/uninhabited type families or type pack families.
DenseHashSet<const void*> uninhabitedTypeFamilies{{}};
// Recorded errors that take place within the solver.
ErrorVec errors;
NotNull<ModuleResolver> moduleResolver;
std::vector<RequireCycle> requireCycles;
DcrLogger* logger;
TypeCheckLimits limits;
explicit ConstraintSolver(NotNull<Normalizer> normalizer, NotNull<Scope> rootScope, std::vector<NotNull<Constraint>> constraints,
ModuleName moduleName, NotNull<ModuleResolver> moduleResolver, std::vector<RequireCycle> requireCycles, DcrLogger* logger,
TypeCheckLimits limits);
// Randomize the order in which to dispatch constraints
void randomize(unsigned seed);
/**
* Attempts to dispatch all pending constraints and reach a type solution
* that satisfies all of the constraints.
**/
void run();
bool isDone();
/** Attempt to dispatch a constraint. Returns true if it was successful. If
* tryDispatch() returns false, the constraint remains in the unsolved set
* and will be retried later.
*/
bool tryDispatch(NotNull<const Constraint> c, bool force);
bool tryDispatch(const SubtypeConstraint& c, NotNull<const Constraint> constraint, bool force);
bool tryDispatch(const PackSubtypeConstraint& c, NotNull<const Constraint> constraint, bool force);
bool tryDispatch(const GeneralizationConstraint& c, NotNull<const Constraint> constraint, bool force);
bool tryDispatch(const IterableConstraint& c, NotNull<const Constraint> constraint, bool force);
bool tryDispatch(const NameConstraint& c, NotNull<const Constraint> constraint);
bool tryDispatch(const TypeAliasExpansionConstraint& c, NotNull<const Constraint> constraint);
bool tryDispatch(const FunctionCallConstraint& c, NotNull<const Constraint> constraint);
bool tryDispatch(const FunctionCheckConstraint& c, NotNull<const Constraint> constraint);
bool tryDispatch(const PrimitiveTypeConstraint& c, NotNull<const Constraint> constraint);
bool tryDispatch(const HasPropConstraint& c, NotNull<const Constraint> constraint);
bool tryDispatchHasIndexer(
int& recursionDepth, NotNull<const Constraint> constraint, TypeId subjectType, TypeId indexType, TypeId resultType, Set<TypeId>& seen);
bool tryDispatch(const HasIndexerConstraint& c, NotNull<const Constraint> constraint);
std::pair<bool, std::optional<TypeId>> tryDispatchSetIndexer(
NotNull<const Constraint> constraint, TypeId subjectType, TypeId indexType, TypeId propType, bool expandFreeTypeBounds);
bool tryDispatch(const AssignConstraint& c, NotNull<const Constraint> constraint);
bool tryDispatch(const AssignPropConstraint& c, NotNull<const Constraint> constraint);
bool tryDispatch(const AssignIndexConstraint& c, NotNull<const Constraint> constraint);
bool tryDispatchUnpack1(NotNull<const Constraint> constraint, TypeId resultType, TypeId sourceType);
bool tryDispatch(const UnpackConstraint& c, NotNull<const Constraint> constraint);
bool tryDispatch(const ReduceConstraint& c, NotNull<const Constraint> constraint, bool force);
bool tryDispatch(const ReducePackConstraint& c, NotNull<const Constraint> constraint, bool force);
bool tryDispatch(const EqualityConstraint& c, NotNull<const Constraint> constraint, bool force);
// for a, ... in some_table do
// also handles __iter metamethod
bool tryDispatchIterableTable(TypeId iteratorTy, const IterableConstraint& c, NotNull<const Constraint> constraint, bool force);
// for a, ... in next_function, t, ... do
bool tryDispatchIterableFunction(
TypeId nextTy, TypeId tableTy, TypeId firstIndexTy, const IterableConstraint& c, NotNull<const Constraint> constraint, bool force);
std::pair<std::vector<TypeId>, std::optional<TypeId>> lookupTableProp(NotNull<const Constraint> constraint, TypeId subjectType,
const std::string& propName, ValueContext context, bool inConditional = false, bool suppressSimplification = false);
std::pair<std::vector<TypeId>, std::optional<TypeId>> lookupTableProp(NotNull<const Constraint> constraint, TypeId subjectType,
const std::string& propName, ValueContext context, bool inConditional, bool suppressSimplification, DenseHashSet<TypeId>& seen);
/**
* Generate constraints to unpack the types of srcTypes and assign each
* value to the corresponding LocalType in destTypes.
*
* @param destTypes A finite TypePack comprised of LocalTypes.
* @param srcTypes A TypePack that represents rvalues to be assigned.
* @returns The underlying UnpackConstraint. There's a bit of code in
* iteration that needs to pass blocks on to this constraint.
*/
NotNull<const Constraint> unpackAndAssign(TypePackId destTypes, TypePackId srcTypes, NotNull<const Constraint> constraint);
void block(NotNull<const Constraint> target, NotNull<const Constraint> constraint);
/**
* Block a constraint on the resolution of a Type.
* @returns false always. This is just to allow tryDispatch to return the result of block()
*/
bool block(TypeId target, NotNull<const Constraint> constraint);
bool block(TypePackId target, NotNull<const Constraint> constraint);
// Block on every target
template<typename T>
bool block(const T& targets, NotNull<const Constraint> constraint)
{
for (TypeId target : targets)
block(target, constraint);
return false;
}
/**
* For all constraints that are blocked on one constraint, make them block
* on a new constraint.
* @param source the constraint to copy blocks from.
* @param addition the constraint that other constraints should now block on.
*/
void inheritBlocks(NotNull<const Constraint> source, NotNull<const Constraint> addition);
// Traverse the type. If any pending types are found, block the constraint
// on them.
//
// Returns false if a type blocks the constraint.
//
// FIXME: This use of a boolean for the return result is an appalling
// interface.
bool blockOnPendingTypes(TypeId target, NotNull<const Constraint> constraint);
bool blockOnPendingTypes(TypePackId target, NotNull<const Constraint> constraint);
void unblock(NotNull<const Constraint> progressed);
void unblock(TypeId progressed, Location location);
void unblock(TypePackId progressed, Location location);
void unblock(const std::vector<TypeId>& types, Location location);
void unblock(const std::vector<TypePackId>& packs, Location location);
/**
* @returns true if the TypeId is in a blocked state.
*/
bool isBlocked(TypeId ty);
/**
* @returns true if the TypePackId is in a blocked state.
*/
bool isBlocked(TypePackId tp);
/**
* Returns whether the constraint is blocked on anything.
* @param constraint the constraint to check.
*/
bool isBlocked(NotNull<const Constraint> constraint);
/** Pushes a new solver constraint to the solver.
* @param cv the body of the constraint.
**/
NotNull<Constraint> pushConstraint(NotNull<Scope> scope, const Location& location, ConstraintV cv);
/**
* Attempts to resolve a module from its module information. Returns the
* module-level return type of the module, or the error type if one cannot
* be found. Reports errors to the solver if the module cannot be found or
* the require is illegal.
* @param module the module information to look up.
* @param location the location where the require is taking place; used for
* error locations.
**/
TypeId resolveModule(const ModuleInfo& module, const Location& location);
void reportError(TypeErrorData&& data, const Location& location);
void reportError(TypeError e);
/**
* Shifts the count of references from `source` to `target`. This should be paired
* with any instance of binding a free type in order to maintain accurate refcounts.
* If `target` is not a free type, this is a noop.
* @param source the free type which is being bound
* @param target the type which the free type is being bound to
*/
void shiftReferences(TypeId source, TypeId target);
/**
* Generalizes the given free type if the reference counting allows it.
* @param the scope to generalize in
* @param type the free type we want to generalize
* @returns a non-free type that generalizes the argument, or `std::nullopt` if one
* does not exist
*/
std::optional<TypeId> generalizeFreeType(NotNull<Scope> scope, TypeId type);
/**
* Checks the existing set of constraints to see if there exist any that contain
* the provided free type, indicating that it is not yet ready to be replaced by
* one of its bounds.
* @param ty the free type that to check for related constraints
* @returns whether or not it is unsafe to replace the free type by one of its bounds
*/
bool hasUnresolvedConstraints(TypeId ty);
/** Attempts to unify subTy with superTy. If doing so would require unifying
* BlockedTypes, fail and block the constraint on those BlockedTypes.
*
* Note: TID can only be TypeId or TypePackId.
*
* If unification fails, replace all free types with errorType.
*
* If unification succeeds, unblock every type changed by the unification.
*
* @returns true if the unification succeeded. False if the unification was
* too complex.
*/
template<typename TID>
bool unify(NotNull<const Constraint> constraint, TID subTy, TID superTy);
private:
/**
* Bind a BlockedType to another type while taking care not to bind it to
* itself in the case that resultTy == blockedTy. This can happen if we
* have a tautological constraint. When it does, we must instead bind
* blockedTy to a fresh type belonging to an appropriate scope.
*
* To determine which scope is appropriate, we also accept rootTy, which is
* to be the type that contains blockedTy.
*
* A constraint is required and will validate that blockedTy is owned by this
* constraint. This prevents one constraint from interfering with another's
* blocked types.
*/
void bindBlockedType(TypeId blockedTy, TypeId resultTy, TypeId rootTy, NotNull<const Constraint> constraint);
/**
* Marks a constraint as being blocked on a type or type pack. The constraint
* solver will not attempt to dispatch blocked constraints until their
* dependencies have made progress.
* @param target the type or type pack pointer that the constraint is blocked on.
* @param constraint the constraint to block.
**/
bool block_(BlockedConstraintId target, NotNull<const Constraint> constraint);
/**
* Informs the solver that progress has been made on a type or type pack. The
* solver will wake up all constraints that are blocked on the type or type pack,
* and will resume attempting to dispatch them.
* @param progressed the type or type pack pointer that has progressed.
**/
void unblock_(BlockedConstraintId progressed);
/**
* Reproduces any constraints necessary for new types that are copied when applying a substitution.
* At the time of writing, this pertains only to type families.
* @param subst the substitution that was applied
**/
void reproduceConstraints(NotNull<Scope> scope, const Location& location, const Substitution& subst);
TypeId errorRecoveryType() const;
TypePackId errorRecoveryTypePack() const;
TypePackId anyifyModuleReturnTypePackGenerics(TypePackId tp);
void throwTimeLimitError();
void throwUserCancelError();
ToStringOptions opts;
};
void dump(NotNull<Scope> rootScope, struct ToStringOptions& opts);
} // namespace Luau