// 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 #include 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; struct HashBlockedConstraintId { size_t operator()(const BlockedConstraintId& bci) const; }; struct ModuleResolver; struct InstantiationSignature { TypeFun fn; std::vector arguments; std::vector 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 arena; NotNull builtinTypes; InternalErrorReporter iceReporter; NotNull normalizer; // The entire set of constraints that the solver is trying to resolve. std::vector> constraints; NotNull rootScope; ModuleName currentModuleName; // Constraints that the solver has generated, rather than sourcing from the // scope tree. std::vector> solverConstraints; // This includes every constraint that has not been fully solved. // A constraint can be both blocked and unsolved, for instance. std::vector> 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, size_t> blockedConstraints; // A mapping of type/pack pointers to the constraints they block. std::unordered_map, HashBlockedConstraintId> blocked; // Memoized instantiations of type aliases. DenseHashMap 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>> upperBoundContributors{nullptr}; // A mapping from free types to the number of unresolved constraints that mention them. DenseHashMap unresolvedConstraints{{}}; // Irreducible/uninhabited type families or type pack families. DenseHashSet uninhabitedTypeFamilies{{}}; // Recorded errors that take place within the solver. ErrorVec errors; NotNull moduleResolver; std::vector requireCycles; DcrLogger* logger; TypeCheckLimits limits; explicit ConstraintSolver(NotNull normalizer, NotNull rootScope, std::vector> constraints, ModuleName moduleName, NotNull moduleResolver, std::vector 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 c, bool force); bool tryDispatch(const SubtypeConstraint& c, NotNull constraint, bool force); bool tryDispatch(const PackSubtypeConstraint& c, NotNull constraint, bool force); bool tryDispatch(const GeneralizationConstraint& c, NotNull constraint, bool force); bool tryDispatch(const IterableConstraint& c, NotNull constraint, bool force); bool tryDispatch(const NameConstraint& c, NotNull constraint); bool tryDispatch(const TypeAliasExpansionConstraint& c, NotNull constraint); bool tryDispatch(const FunctionCallConstraint& c, NotNull constraint); bool tryDispatch(const FunctionCheckConstraint& c, NotNull constraint); bool tryDispatch(const PrimitiveTypeConstraint& c, NotNull constraint); bool tryDispatch(const HasPropConstraint& c, NotNull constraint); bool tryDispatchHasIndexer( int& recursionDepth, NotNull constraint, TypeId subjectType, TypeId indexType, TypeId resultType, Set& seen); bool tryDispatch(const HasIndexerConstraint& c, NotNull constraint); std::pair> tryDispatchSetIndexer( NotNull constraint, TypeId subjectType, TypeId indexType, TypeId propType, bool expandFreeTypeBounds); bool tryDispatch(const AssignConstraint& c, NotNull constraint); bool tryDispatch(const AssignPropConstraint& c, NotNull constraint); bool tryDispatch(const AssignIndexConstraint& c, NotNull constraint); bool tryDispatchUnpack1(NotNull constraint, TypeId resultType, TypeId sourceType); bool tryDispatch(const UnpackConstraint& c, NotNull constraint); bool tryDispatch(const ReduceConstraint& c, NotNull constraint, bool force); bool tryDispatch(const ReducePackConstraint& c, NotNull constraint, bool force); bool tryDispatch(const EqualityConstraint& c, NotNull constraint, bool force); // for a, ... in some_table do // also handles __iter metamethod bool tryDispatchIterableTable(TypeId iteratorTy, const IterableConstraint& c, NotNull constraint, bool force); // for a, ... in next_function, t, ... do bool tryDispatchIterableFunction( TypeId nextTy, TypeId tableTy, TypeId firstIndexTy, const IterableConstraint& c, NotNull constraint, bool force); std::pair, std::optional> lookupTableProp(NotNull constraint, TypeId subjectType, const std::string& propName, ValueContext context, bool inConditional = false, bool suppressSimplification = false); std::pair, std::optional> lookupTableProp(NotNull constraint, TypeId subjectType, const std::string& propName, ValueContext context, bool inConditional, bool suppressSimplification, DenseHashSet& 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 unpackAndAssign(TypePackId destTypes, TypePackId srcTypes, NotNull constraint); void block(NotNull target, NotNull 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 constraint); bool block(TypePackId target, NotNull constraint); // Block on every target template bool block(const T& targets, NotNull 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 source, NotNull 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 constraint); bool blockOnPendingTypes(TypePackId target, NotNull constraint); void unblock(NotNull progressed); void unblock(TypeId progressed, Location location); void unblock(TypePackId progressed, Location location); void unblock(const std::vector& types, Location location); void unblock(const std::vector& 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 constraint); /** Pushes a new solver constraint to the solver. * @param cv the body of the constraint. **/ NotNull pushConstraint(NotNull 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 generalizeFreeType(NotNull 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 bool unify(NotNull 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 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 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, 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 rootScope, struct ToStringOptions& opts); } // namespace Luau