luau/Analysis/include/Luau/Unifier2.h
Lily Brown 47ad768c69
Sync to upstream/release/619 (#1218)
# What's Changed

## New Type Solver
- Many fixes to crashes, assertions, and hangs
- Binary type family aliases now have a default parameter
- Added a debug check for unsolved types escaping the constraint solver
- Overloaded functions are no longer inferred
- Unification creates additional subtyping constraints for blocked types
- Attempt to guess the result type for type families that are too large
to resolve timely

## Native Code Generation
- Fixed `IrCmd::CHECK_TRUTHY` lowering in a specific case
- Detailed compilation errors are now supported
- More work on the new allocator

---

# 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: James McNellis <jmcnellis@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
2024-03-30 16:14:44 -07:00

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// 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/NotNull.h"
#include "Luau/TypeCheckLimits.h"
#include "Luau/TypeFwd.h"
#include "Luau/TypePairHash.h"
#include <optional>
#include <vector>
#include <utility>
namespace Luau
{
struct InternalErrorReporter;
struct Scope;
struct TypeArena;
enum class OccursCheckResult
{
Pass,
Fail
};
struct Unifier2
{
NotNull<TypeArena> arena;
NotNull<BuiltinTypes> builtinTypes;
NotNull<Scope> scope;
NotNull<InternalErrorReporter> ice;
TypeCheckLimits limits;
DenseHashSet<std::pair<TypeId, TypeId>, TypePairHash> seenTypePairings{{nullptr, nullptr}};
DenseHashSet<std::pair<TypePackId, TypePackId>, TypePairHash> seenTypePackPairings{{nullptr, nullptr}};
DenseHashMap<TypeId, std::vector<TypeId>> expandedFreeTypes{nullptr};
// Mapping from generic types to free types to be used in instantiation.
DenseHashMap<TypeId, TypeId> genericSubstitutions{nullptr};
// Mapping from generic type packs to `TypePack`s of free types to be used in instantiation.
DenseHashMap<TypePackId, TypePackId> genericPackSubstitutions{nullptr};
int recursionCount = 0;
int recursionLimit = 0;
std::vector<ConstraintV> incompleteSubtypes;
Unifier2(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtinTypes, NotNull<Scope> scope, NotNull<InternalErrorReporter> ice);
/** Attempt to commit the subtype relation subTy <: superTy to the type
* graph.
*
* @returns true if successful.
*
* Note that incoherent types can and will successfully be unified. We stop
* when we *cannot know* how to relate the provided types, not when doing so
* would narrow something down to never or broaden it to unknown.
*
* Presently, the only way unification can fail is if we attempt to bind one
* free TypePack to another and encounter an occurs check violation.
*/
bool unify(TypeId subTy, TypeId superTy);
bool unifyFreeWithType(TypeId subTy, TypeId superTy);
bool unify(const LocalType* subTy, TypeId superFn);
bool unify(TypeId subTy, const FunctionType* superFn);
bool unify(const UnionType* subUnion, TypeId superTy);
bool unify(TypeId subTy, const UnionType* superUnion);
bool unify(const IntersectionType* subIntersection, TypeId superTy);
bool unify(TypeId subTy, const IntersectionType* superIntersection);
bool unify(TableType* subTable, const TableType* superTable);
bool unify(const MetatableType* subMetatable, const MetatableType* superMetatable);
// TODO think about this one carefully. We don't do unions or intersections of type packs
bool unify(TypePackId subTp, TypePackId superTp);
std::optional<TypeId> generalize(TypeId ty);
private:
/**
* @returns simplify(left | right)
*/
TypeId mkUnion(TypeId left, TypeId right);
/**
* @returns simplify(left & right)
*/
TypeId mkIntersection(TypeId left, TypeId right);
// Returns true if needle occurs within haystack already. ie if we bound
// needle to haystack, would a cyclic type result?
OccursCheckResult occursCheck(DenseHashSet<TypeId>& seen, TypeId needle, TypeId haystack);
// Returns true if needle occurs within haystack already. ie if we bound
// needle to haystack, would a cyclic TypePack result?
OccursCheckResult occursCheck(DenseHashSet<TypePackId>& seen, TypePackId needle, TypePackId haystack);
};
} // namespace Luau