luau/Analysis/include/Luau/Unifier.h

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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/Error.h"
#include "Luau/Location.h"
#include "Luau/TxnLog.h"
#include "Luau/TypeInfer.h"
#include "Luau/Module.h" // FIXME: For TypeArena. It merits breaking out into its own header.
#include <unordered_set>
namespace Luau
{
enum Variance
{
Covariant,
Invariant
};
struct UnifierCounters
{
int recursionCount = 0;
int iterationCount = 0;
};
struct Unifier
{
TypeArena* const types;
Mode mode;
ScopePtr globalScope; // sigh. Needed solely to get at string's metatable.
TxnLog log;
ErrorVec errors;
Location location;
Variance variance = Covariant;
CountMismatch::Context ctx = CountMismatch::Arg;
UnifierCounters* counters;
UnifierCounters countersData;
std::shared_ptr<UnifierCounters> counters_DEPRECATED;
InternalErrorReporter* iceHandler;
Unifier(TypeArena* types, Mode mode, ScopePtr globalScope, const Location& location, Variance variance, InternalErrorReporter* iceHandler);
Unifier(TypeArena* types, Mode mode, ScopePtr globalScope, const std::vector<std::pair<TypeId, TypeId>>& seen, const Location& location,
Variance variance, InternalErrorReporter* iceHandler, const std::shared_ptr<UnifierCounters>& counters_DEPRECATED = nullptr,
UnifierCounters* counters = nullptr);
// Test whether the two type vars unify. Never commits the result.
ErrorVec canUnify(TypeId superTy, TypeId subTy);
ErrorVec canUnify(TypePackId superTy, TypePackId subTy, bool isFunctionCall = false);
/** Attempt to unify left with right.
* Populate the vector errors with any type errors that may arise.
* Populate the transaction log with the set of TypeIds that need to be reset to undo the unification attempt.
*/
void tryUnify(TypeId superTy, TypeId subTy, bool isFunctionCall = false, bool isIntersection = false);
private:
void tryUnify_(TypeId superTy, TypeId subTy, bool isFunctionCall = false, bool isIntersection = false);
void tryUnifyPrimitives(TypeId superTy, TypeId subTy);
void tryUnifyFunctions(TypeId superTy, TypeId subTy, bool isFunctionCall = false);
void tryUnifyTables(TypeId left, TypeId right, bool isIntersection = false);
void DEPRECATED_tryUnifyTables(TypeId left, TypeId right, bool isIntersection = false);
void tryUnifyFreeTable(TypeId free, TypeId other);
void tryUnifySealedTables(TypeId left, TypeId right, bool isIntersection);
void tryUnifyWithMetatable(TypeId metatable, TypeId other, bool reversed);
void tryUnifyWithClass(TypeId superTy, TypeId subTy, bool reversed);
void tryUnify(const TableIndexer& superIndexer, const TableIndexer& subIndexer);
TypeId deeplyOptional(TypeId ty, std::unordered_map<TypeId,TypeId> seen = {});
public:
void tryUnify(TypePackId superTy, TypePackId subTy, bool isFunctionCall = false);
private:
void tryUnify_(TypePackId superTy, TypePackId subTy, bool isFunctionCall = false);
void tryUnifyVariadics(TypePackId superTy, TypePackId subTy, bool reversed, int subOffset = 0);
void tryUnifyWithAny(TypeId any, TypeId ty);
void tryUnifyWithAny(TypePackId any, TypePackId ty);
std::optional<TypeId> findTablePropertyRespectingMeta(TypeId lhsType, Name name);
std::optional<TypeId> findMetatableEntry(TypeId type, std::string entry);
public:
// Report an "infinite type error" if the type "needle" already occurs within "haystack"
void occursCheck(TypeId needle, TypeId haystack);
void occursCheck(std::unordered_set<TypeId>& seen_DEPRECATED, DenseHashSet<TypeId>& seen, TypeId needle, TypeId haystack);
void occursCheck(TypePackId needle, TypePackId haystack);
void occursCheck(std::unordered_set<TypePackId>& seen_DEPRECATED, DenseHashSet<TypePackId>& seen, TypePackId needle, TypePackId haystack);
Unifier makeChildUnifier();
private:
bool isNonstrictMode() const;
void checkChildUnifierTypeMismatch(const ErrorVec& innerErrors, TypeId wantedType, TypeId givenType);
[[noreturn]] void ice(const std::string& message, const Location& location);
[[noreturn]] void ice(const std::string& message);
DenseHashSet<TypeId> tempSeenTy{nullptr};
DenseHashSet<TypePackId> tempSeenTp{nullptr};
};
} // namespace Luau