luau/Analysis/include/Luau/Unifier2.h
Alexander McCord c2ba1058c3
Sync to upstream/release/603 (#1097)
# What's changed?

- Record the location of properties for table types (closes #802)
- Implement stricter UTF-8 validations as per the RFC
(https://github.com/luau-lang/rfcs/pull/1)
- Implement `buffer` as a new type in both the old and new solvers.
- Changed errors produced by some `buffer` builtins to be a bit more
generic to avoid platform-dependent error messages.
- Fixed a bug where `Unifier` would copy some persistent types, tripping
some internal assertions.
- Type checking rules on relational operators is now a little bit more
lax.
- Improve dead code elimination for some `if` statements with complex
always-false conditions

## New type solver

- Dataflow analysis now generates phi nodes on exit of branches.
- Dataflow analysis avoids producing a new definition for locals or
properties that are not owned by that loop.
- If a function parameter has been constrained to `never`, report errors
at all uses of that parameter within that function.
- Switch to using the new `Luau::Set` to replace `std::unordered_set` to
alleviate some poor allocation characteristics which was negatively
affecting overall performance.
- Subtyping can now report many failing reasons instead of just the
first one that we happened to find during the test.
- Subtyping now also report reasons for type pack mismatches.
- When visiting `if` statements or expressions, the resulting context
are the common terms in both branches.

## Native codegen

- Implement support for `buffer` builtins to its IR for x64 and A64.
- Optimized `table.insert` by not inserting a table barrier if it is
fastcalled with a constant.

## 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: Arseny Kapoulkine <arseny@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
2023-11-10 13:10:07 -08:00

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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/DenseHash.h"
#include "Luau/NotNull.h"
#include "Luau/TypePairHash.h"
#include "Luau/TypeCheckLimits.h"
#include "Luau/TypeFwd.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};
int recursionCount = 0;
int recursionLimit = 0;
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 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(const 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 TypePack result?
OccursCheckResult occursCheck(DenseHashSet<TypePackId>& seen, TypePackId needle, TypePackId haystack);
};
} // namespace Luau