// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
#include "Luau/Anyification.h"
#include "Luau/ApplyTypeFunction.h"
#include "Luau/Clone.h"
#include "Luau/Common.h"
#include "Luau/ConstraintSolver.h"
#include "Luau/DcrLogger.h"
#include "Luau/Instantiation.h"
#include "Luau/Location.h"
#include "Luau/Metamethods.h"
#include "Luau/ModuleResolver.h"
#include "Luau/Quantify.h"
#include "Luau/Simplify.h"
#include "Luau/ToString.h"
#include "Luau/Type.h"
#include "Luau/TypeFamily.h"
#include "Luau/TypeUtils.h"
#include "Luau/Unifier.h"
#include "Luau/VisitType.h"
LUAU_FASTFLAGVARIABLE(DebugLuauLogSolver, false);
namespace Luau
{
size_t HashBlockedConstraintId::operator()(const BlockedConstraintId& bci) const
{
size_t result = 0;
if (const TypeId* ty = get_if<TypeId>(&bci))
result = std::hash<TypeId>()(*ty);
else if (const TypePackId* tp = get_if<TypePackId>(&bci))
result = std::hash<TypePackId>()(*tp);
else if (Constraint const* const* c = get_if<const Constraint*>(&bci))
result = std::hash<const Constraint*>()(*c);
else
LUAU_ASSERT(!"Should be unreachable");
return result;
}
[[maybe_unused]] static void dumpBindings(NotNull<Scope> scope, ToStringOptions& opts)
{
for (const auto& [k, v] : scope->bindings)
{
auto d = toString(v.typeId, opts);
printf("\t%s : %s\n", k.c_str(), d.c_str());
}
for (NotNull<Scope> child : scope->children)
dumpBindings(child, opts);
}
static std::pair<std::vector<TypeId>, std::vector<TypePackId>> saturateArguments(TypeArena* arena, NotNull<BuiltinTypes> builtinTypes,
const TypeFun& fn, const std::vector<TypeId>& rawTypeArguments, const std::vector<TypePackId>& rawPackArguments)
{
std::vector<TypeId> saturatedTypeArguments;
std::vector<TypeId> extraTypes;
std::vector<TypePackId> saturatedPackArguments;
for (size_t i = 0; i < rawTypeArguments.size(); ++i)
{
TypeId ty = rawTypeArguments[i];
if (i < fn.typeParams.size())
saturatedTypeArguments.push_back(ty);
else
extraTypes.push_back(ty);
}
// If we collected extra types, put them in a type pack now. This case is
// mutually exclusive with the type pack -> type conversion we do below:
// extraTypes will only have elements in it if we have more types than we
// have parameter slots for them to go into.
if (!extraTypes.empty() && !fn.typePackParams.empty())
{
saturatedPackArguments.push_back(arena->addTypePack(extraTypes));
}
for (size_t i = 0; i < rawPackArguments.size(); ++i)
{
TypePackId tp = rawPackArguments[i];
// If we are short on regular type saturatedTypeArguments and we have a single
// element type pack, we can decompose that to the type it contains and
// use that as a type parameter.
if (saturatedTypeArguments.size() < fn.typeParams.size() && size(tp) == 1 && finite(tp) && first(tp) && saturatedPackArguments.empty())
{
saturatedTypeArguments.push_back(*first(tp));
}
else if (saturatedPackArguments.size() < fn.typePackParams.size())
{
saturatedPackArguments.push_back(tp);
}
}
size_t typesProvided = saturatedTypeArguments.size();
size_t typesRequired = fn.typeParams.size();
size_t packsProvided = saturatedPackArguments.size();
size_t packsRequired = fn.typePackParams.size();
// Extra types should be accumulated in extraTypes, not saturatedTypeArguments. Extra
// packs will be accumulated in saturatedPackArguments, so we don't have an
// assertion for that.
LUAU_ASSERT(typesProvided <= typesRequired);
// If we didn't provide enough types, but we did provide a type pack, we
// don't want to use defaults. The rationale for this is that if the user
// provides a pack but doesn't provide enough types, we want to report an
// error, rather than simply using the default saturatedTypeArguments, if they exist. If
// they did provide enough types, but not enough packs, we of course want to
// use the default packs.
bool needsDefaults = (typesProvided < typesRequired && packsProvided == 0) || (typesProvided == typesRequired && packsProvided < packsRequired);
if (needsDefaults)
{
// Default types can reference earlier types. It's legal to write
// something like
// type T<A, B = A> = (A, B) -> number
// and we need to respect that. We use an ApplyTypeFunction for this.
ApplyTypeFunction atf{arena};
for (size_t i = 0; i < typesProvided; ++i)
atf.typeArguments[fn.typeParams[i].ty] = saturatedTypeArguments[i];
for (size_t i = typesProvided; i < typesRequired; ++i)
{
TypeId defaultTy = fn.typeParams[i].defaultValue.value_or(nullptr);
// We will fill this in with the error type later.
if (!defaultTy)
break;
TypeId instantiatedDefault = atf.substitute(defaultTy).value_or(builtinTypes->errorRecoveryType());
atf.typeArguments[fn.typeParams[i].ty] = instantiatedDefault;
saturatedTypeArguments.push_back(instantiatedDefault);
}
for (size_t i = 0; i < packsProvided; ++i)
{
atf.typePackArguments[fn.typePackParams[i].tp] = saturatedPackArguments[i];
}
for (size_t i = packsProvided; i < packsRequired; ++i)
{
TypePackId defaultTp = fn.typePackParams[i].defaultValue.value_or(nullptr);
// We will fill this in with the error type pack later.
if (!defaultTp)
break;
TypePackId instantiatedDefault = atf.substitute(defaultTp).value_or(builtinTypes->errorRecoveryTypePack());
atf.typePackArguments[fn.typePackParams[i].tp] = instantiatedDefault;
saturatedPackArguments.push_back(instantiatedDefault);
}
}
// If we didn't create an extra type pack from overflowing parameter packs,
// and we're still missing a type pack, plug in an empty type pack as the
// value of the empty packs.
if (extraTypes.empty() && saturatedPackArguments.size() + 1 == fn.typePackParams.size())
{
saturatedPackArguments.push_back(arena->addTypePack({}));
}
// We need to have _something_ when we substitute the generic saturatedTypeArguments,
// even if they're missing, so we use the error type as a filler.
for (size_t i = saturatedTypeArguments.size(); i < typesRequired; ++i)
{
saturatedTypeArguments.push_back(builtinTypes->errorRecoveryType());
}
for (size_t i = saturatedPackArguments.size(); i < packsRequired; ++i)
{
saturatedPackArguments.push_back(builtinTypes->errorRecoveryTypePack());
}
// At this point, these two conditions should be true. If they aren't we
// will run into access violations.
LUAU_ASSERT(saturatedTypeArguments.size() == fn.typeParams.size());
LUAU_ASSERT(saturatedPackArguments.size() == fn.typePackParams.size());
return {saturatedTypeArguments, saturatedPackArguments};
}
bool InstantiationSignature::operator==(const InstantiationSignature& rhs) const
{
return fn == rhs.fn && arguments == rhs.arguments && packArguments == rhs.packArguments;
}
size_t HashInstantiationSignature::operator()(const InstantiationSignature& signature) const
{
size_t hash = std::hash<TypeId>{}(signature.fn.type);
for (const GenericTypeDefinition& p : signature.fn.typeParams)
{
hash ^= (std::hash<TypeId>{}(p.ty) << 1);
}
for (const GenericTypePackDefinition& p : signature.fn.typePackParams)
{
hash ^= (std::hash<TypePackId>{}(p.tp) << 1);
}
for (const TypeId a : signature.arguments)
{
hash ^= (std::hash<TypeId>{}(a) << 1);
}
for (const TypePackId a : signature.packArguments)
{
hash ^= (std::hash<TypePackId>{}(a) << 1);
}
return hash;
}
void dump(ConstraintSolver* cs, ToStringOptions& opts)
{
printf("constraints:\n");
for (NotNull<const Constraint> c : cs->unsolvedConstraints)
{
auto it = cs->blockedConstraints.find(c);
int blockCount = it == cs->blockedConstraints.end() ? 0 : int(it->second);
printf("\t%d\t%s\n", blockCount, toString(*c, opts).c_str());
}
}
struct InstantiationQueuer : TypeOnceVisitor
{
ConstraintSolver* solver;
NotNull<Scope> scope;
Location location;
explicit InstantiationQueuer(NotNull<Scope> scope, const Location& location, ConstraintSolver* solver)
: solver(solver)
, scope(scope)
, location(location)
{
}
bool visit(TypeId ty, const PendingExpansionType& petv) override
{
solver->pushConstraint(scope, location, TypeAliasExpansionConstraint{ty});
return false;
}
bool visit(TypeId ty, const TypeFamilyInstanceType& tfit) override
{
solver->pushConstraint(scope, location, ReduceConstraint{ty});
return true;
}
bool visit(TypeId ty, const ClassType& ctv) override
{
return false;
}
};
ConstraintSolver::ConstraintSolver(NotNull<Normalizer> normalizer, NotNull<Scope> rootScope, std::vector<NotNull<Constraint>> constraints,
ModuleName moduleName, NotNull<ModuleResolver> moduleResolver, std::vector<RequireCycle> requireCycles, DcrLogger* logger)
: arena(normalizer->arena)
, builtinTypes(normalizer->builtinTypes)
, normalizer(normalizer)
, constraints(std::move(constraints))
, rootScope(rootScope)
, currentModuleName(std::move(moduleName))
, moduleResolver(moduleResolver)
, requireCycles(requireCycles)
, logger(logger)
{
opts.exhaustive = true;
for (NotNull<Constraint> c : this->constraints)
{
unsolvedConstraints.push_back(c);
for (NotNull<const Constraint> dep : c->dependencies)
{
block(dep, c);
}
}
}
void ConstraintSolver::randomize(unsigned seed)
{
if (unsolvedConstraints.empty())
return;
unsigned int rng = seed;
for (size_t i = unsolvedConstraints.size() - 1; i > 0; --i)
{
// Fisher-Yates shuffle
size_t j = rng % (i + 1);
std::swap(unsolvedConstraints[i], unsolvedConstraints[j]);
// LCG RNG, constants from Numerical Recipes
// This may occasionally result in skewed shuffles due to distribution properties, but this is a debugging tool so it should be good enough
rng = rng * 1664525 + 1013904223;
}
}
void ConstraintSolver::run()
{
if (isDone())
return;
if (FFlag::DebugLuauLogSolver)
{
printf("Starting solver\n");
dump(this, opts);
printf("Bindings:\n");
dumpBindings(rootScope, opts);
}
if (logger)
{
logger->captureInitialSolverState(rootScope, unsolvedConstraints);
}
auto runSolverPass = [&](bool force) {
bool progress = false;
size_t i = 0;
while (i < unsolvedConstraints.size())
{
NotNull<const Constraint> c = unsolvedConstraints[i];
if (!force && isBlocked(c))
{
++i;
continue;
}
std::string saveMe = FFlag::DebugLuauLogSolver ? toString(*c, opts) : std::string{};
StepSnapshot snapshot;
if (logger)
{
snapshot = logger->prepareStepSnapshot(rootScope, c, force, unsolvedConstraints);
}
bool success = tryDispatch(c, force);
progress |= success;
if (success)
{
unblock(c);
unsolvedConstraints.erase(unsolvedConstraints.begin() + i);
if (logger)
{
logger->commitStepSnapshot(snapshot);
}
if (FFlag::DebugLuauLogSolver)
{
if (force)
printf("Force ");
printf("Dispatched\n\t%s\n", saveMe.c_str());
if (force)
{
printf("Blocked on:\n");
for (const auto& [bci, cv] : blocked)
{
if (end(cv) == std::find(begin(cv), end(cv), c))
continue;
if (auto bty = get_if<TypeId>(&bci))
printf("\tType %s\n", toString(*bty, opts).c_str());
else if (auto btp = get_if<TypePackId>(&bci))
printf("\tPack %s\n", toString(*btp, opts).c_str());
else if (auto cc = get_if<const Constraint*>(&bci))
printf("\tCons %s\n", toString(**cc, opts).c_str());
else
LUAU_ASSERT(!"Unreachable??");
}
}
dump(this, opts);
}
}
else
++i;
if (force && success)
return true;
}
return progress;
};
bool progress = false;
do
{
progress = runSolverPass(false);
if (!progress)
progress |= runSolverPass(true);
} while (progress);
finalizeModule();
if (FFlag::DebugLuauLogSolver)
{
dumpBindings(rootScope, opts);
}
if (logger)
{
logger->captureFinalSolverState(rootScope, unsolvedConstraints);
}
}
bool ConstraintSolver::isDone()
{
return unsolvedConstraints.empty();
}
void ConstraintSolver::finalizeModule()
{
Anyification a{arena, rootScope, builtinTypes, &iceReporter, builtinTypes->anyType, builtinTypes->anyTypePack};
std::optional<TypePackId> returnType = a.substitute(rootScope->returnType);
if (!returnType)
{
reportError(CodeTooComplex{}, Location{});
rootScope->returnType = builtinTypes->errorTypePack;
}
else
{
rootScope->returnType = anyifyModuleReturnTypePackGenerics(*returnType);
}
}
bool ConstraintSolver::tryDispatch(NotNull<const Constraint> constraint, bool force)
{
if (!force && isBlocked(constraint))
return false;
bool success = false;
if (auto sc = get<SubtypeConstraint>(*constraint))
success = tryDispatch(*sc, constraint, force);
else if (auto psc = get<PackSubtypeConstraint>(*constraint))
success = tryDispatch(*psc, constraint, force);
else if (auto gc = get<GeneralizationConstraint>(*constraint))
success = tryDispatch(*gc, constraint, force);
else if (auto ic = get<InstantiationConstraint>(*constraint))
success = tryDispatch(*ic, constraint, force);
else if (auto uc = get<UnaryConstraint>(*constraint))
success = tryDispatch(*uc, constraint, force);
else if (auto bc = get<BinaryConstraint>(*constraint))
success = tryDispatch(*bc, constraint, force);
else if (auto ic = get<IterableConstraint>(*constraint))
success = tryDispatch(*ic, constraint, force);
else if (auto nc = get<NameConstraint>(*constraint))
success = tryDispatch(*nc, constraint);
else if (auto taec = get<TypeAliasExpansionConstraint>(*constraint))
success = tryDispatch(*taec, constraint);
else if (auto fcc = get<FunctionCallConstraint>(*constraint))
success = tryDispatch(*fcc, constraint);
else if (auto fcc = get<PrimitiveTypeConstraint>(*constraint))
success = tryDispatch(*fcc, constraint);
else if (auto hpc = get<HasPropConstraint>(*constraint))
success = tryDispatch(*hpc, constraint);
else if (auto spc = get<SetPropConstraint>(*constraint))
success = tryDispatch(*spc, constraint, force);
else if (auto spc = get<SetIndexerConstraint>(*constraint))
success = tryDispatch(*spc, constraint, force);
else if (auto sottc = get<SingletonOrTopTypeConstraint>(*constraint))
success = tryDispatch(*sottc, constraint);
else if (auto uc = get<UnpackConstraint>(*constraint))
success = tryDispatch(*uc, constraint);
else if (auto rc = get<RefineConstraint>(*constraint))
success = tryDispatch(*rc, constraint, force);
else if (auto rc = get<ReduceConstraint>(*constraint))
success = tryDispatch(*rc, constraint, force);
else if (auto rpc = get<ReducePackConstraint>(*constraint))
success = tryDispatch(*rpc, constraint, force);
else
LUAU_ASSERT(false);
if (success)
unblock(constraint);
return success;
}
bool ConstraintSolver::tryDispatch(const SubtypeConstraint& c, NotNull<const Constraint> constraint, bool force)
{
if (isBlocked(c.subType))
return block(c.subType, constraint);
else if (isBlocked(c.superType))
return block(c.superType, constraint);
return tryUnify(constraint, c.subType, c.superType);
}
bool ConstraintSolver::tryDispatch(const PackSubtypeConstraint& c, NotNull<const Constraint> constraint, bool force)
{
if (isBlocked(c.subPack))
return block(c.subPack, constraint);
else if (isBlocked(c.superPack))
return block(c.superPack, constraint);
return tryUnify(constraint, c.subPack, c.superPack);
}
bool ConstraintSolver::tryDispatch(const GeneralizationConstraint& c, NotNull<const Constraint> constraint, bool force)
{
TypeId generalizedType = follow(c.generalizedType);
if (isBlocked(c.sourceType))
return block(c.sourceType, constraint);
else if (get<PendingExpansionType>(generalizedType))
return block(generalizedType, constraint);
std::optional<QuantifierResult> generalized = quantify(arena, c.sourceType, constraint->scope);
if (generalized)
{
if (get<BlockedType>(generalizedType))
asMutable(generalizedType)->ty.emplace<BoundType>(generalized->result);
else
unify(generalizedType, generalized->result, constraint->scope);
for (auto [free, gen] : generalized->insertedGenerics.pairings)
unify(free, gen, constraint->scope);
for (auto [free, gen] : generalized->insertedGenericPacks.pairings)
unify(free, gen, constraint->scope);
}
else
{
reportError(CodeTooComplex{}, constraint->location);
asMutable(c.generalizedType)->ty.emplace<BoundType>(builtinTypes->errorRecoveryType());
}
unblock(c.generalizedType);
unblock(c.sourceType);
return true;
}
bool ConstraintSolver::tryDispatch(const InstantiationConstraint& c, NotNull<const Constraint> constraint, bool force)
{
if (isBlocked(c.superType))
return block(c.superType, constraint);
if (!blockOnPendingTypes(c.superType, constraint))
return false;
Instantiation inst(TxnLog::empty(), arena, TypeLevel{}, constraint->scope);
std::optional<TypeId> instantiated = inst.substitute(c.superType);
LUAU_ASSERT(get<BlockedType>(c.subType));
if (!instantiated.has_value())
{
reportError(UnificationTooComplex{}, constraint->location);
asMutable(c.subType)->ty.emplace<BoundType>(errorRecoveryType());
unblock(c.subType);
return true;
}
asMutable(c.subType)->ty.emplace<BoundType>(*instantiated);
InstantiationQueuer queuer{constraint->scope, constraint->location, this};
queuer.traverse(c.subType);
unblock(c.subType);
return true;
}
bool ConstraintSolver::tryDispatch(const UnaryConstraint& c, NotNull<const Constraint> constraint, bool force)
{
TypeId operandType = follow(c.operandType);
if (isBlocked(operandType))
return block(operandType, constraint);
if (get<FreeType>(operandType))
return block(operandType, constraint);
LUAU_ASSERT(get<BlockedType>(c.resultType));
switch (c.op)
{
case AstExprUnary::Not:
{
asMutable(c.resultType)->ty.emplace<BoundType>(builtinTypes->booleanType);
unblock(c.resultType);
return true;
}
case AstExprUnary::Len:
{
// __len must return a number.
asMutable(c.resultType)->ty.emplace<BoundType>(builtinTypes->numberType);
unblock(c.resultType);
return true;
}
case AstExprUnary::Minus:
{
if (isNumber(operandType) || get<AnyType>(operandType) || get<ErrorType>(operandType) || get<NeverType>(operandType))
{
asMutable(c.resultType)->ty.emplace<BoundType>(c.operandType);
}
else if (std::optional<TypeId> mm = findMetatableEntry(builtinTypes, errors, operandType, "__unm", constraint->location))
{
TypeId mmTy = follow(*mm);
if (get<FreeType>(mmTy) && !force)
return block(mmTy, constraint);
TypePackId argPack = arena->addTypePack(TypePack{{operandType}, {}});
TypePackId retPack = arena->addTypePack(BlockedTypePack{});
asMutable(c.resultType)->ty.emplace<FreeType>(constraint->scope);
pushConstraint(constraint->scope, constraint->location, PackSubtypeConstraint{retPack, arena->addTypePack(TypePack{{c.resultType}})});
pushConstraint(constraint->scope, constraint->location, FunctionCallConstraint{mmTy, argPack, retPack, nullptr});
}
else
{
asMutable(c.resultType)->ty.emplace<BoundType>(builtinTypes->errorRecoveryType());
}
unblock(c.resultType);
return true;
}
}
LUAU_ASSERT(false);
return false;
}
bool ConstraintSolver::tryDispatch(const BinaryConstraint& c, NotNull<const Constraint> constraint, bool force)
{
TypeId leftType = follow(c.leftType);
TypeId rightType = follow(c.rightType);
TypeId resultType = follow(c.resultType);
LUAU_ASSERT(get<BlockedType>(resultType));
bool isLogical = c.op == AstExprBinary::Op::And || c.op == AstExprBinary::Op::Or;
/* Compound assignments create constraints of the form
*
* A <: Binary<op, A, B>
*
* This constraint is the one that is meant to unblock A, so it doesn't
* make any sense to stop and wait for someone else to do it.
*/
// If any is present, the expression must evaluate to any as well.
bool leftAny = get<AnyType>(leftType) || get<ErrorType>(leftType);
bool rightAny = get<AnyType>(rightType) || get<ErrorType>(rightType);
bool anyPresent = leftAny || rightAny;
if (isBlocked(leftType) && leftType != resultType)
return block(c.leftType, constraint);
if (isBlocked(rightType) && rightType != resultType)
return block(c.rightType, constraint);
if (!force)
{
// Logical expressions may proceed if the LHS is free.
if (hasTypeInIntersection<FreeType>(leftType) && !isLogical)
return block(leftType, constraint);
}
// Logical expressions may proceed if the LHS is free.
if (isBlocked(leftType) || (hasTypeInIntersection<FreeType>(leftType) && !isLogical))
{
asMutable(resultType)->ty.emplace<BoundType>(errorRecoveryType());
unblock(resultType);
return true;
}
// Metatables go first, even if there is primitive behavior.
if (auto it = kBinaryOpMetamethods.find(c.op); it != kBinaryOpMetamethods.end())
{
// Metatables are not the same. The metamethod will not be invoked.
if ((c.op == AstExprBinary::Op::CompareEq || c.op == AstExprBinary::Op::CompareNe) &&
getMetatable(leftType, builtinTypes) != getMetatable(rightType, builtinTypes))
{
// TODO: Boolean singleton false? The result is _always_ boolean false.
asMutable(resultType)->ty.emplace<BoundType>(builtinTypes->booleanType);
unblock(resultType);
return true;
}
std::optional<TypeId> mm;
// The LHS metatable takes priority over the RHS metatable, where
// present.
if (std::optional<TypeId> leftMm = findMetatableEntry(builtinTypes, errors, leftType, it->second, constraint->location))
mm = leftMm;
else if (std::optional<TypeId> rightMm = findMetatableEntry(builtinTypes, errors, rightType, it->second, constraint->location))
mm = rightMm;
if (mm)
{
Instantiation instantiation{TxnLog::empty(), arena, TypeLevel{}, constraint->scope};
std::optional<TypeId> instantiatedMm = instantiation.substitute(*mm);
if (!instantiatedMm)
{
reportError(CodeTooComplex{}, constraint->location);
return true;
}
// TODO: Is a table with __call legal here?
// TODO: Overloads
if (const FunctionType* ftv = get<FunctionType>(follow(*instantiatedMm)))
{
TypePackId inferredArgs;
// For >= and > we invoke __lt and __le respectively with
// swapped argument ordering.
if (c.op == AstExprBinary::Op::CompareGe || c.op == AstExprBinary::Op::CompareGt)
{
inferredArgs = arena->addTypePack({rightType, leftType});
}
else
{
inferredArgs = arena->addTypePack({leftType, rightType});
}
unify(inferredArgs, ftv->argTypes, constraint->scope);
TypeId mmResult;
// Comparison operations always evaluate to a boolean,
// regardless of what the metamethod returns.
switch (c.op)
{
case AstExprBinary::Op::CompareEq:
case AstExprBinary::Op::CompareNe:
case AstExprBinary::Op::CompareGe:
case AstExprBinary::Op::CompareGt:
case AstExprBinary::Op::CompareLe:
case AstExprBinary::Op::CompareLt:
mmResult = builtinTypes->booleanType;
break;
default:
if (get<NeverType>(leftType) || get<NeverType>(rightType))
mmResult = builtinTypes->neverType;
else
mmResult = first(ftv->retTypes).value_or(errorRecoveryType());
}
asMutable(resultType)->ty.emplace<BoundType>(mmResult);
unblock(resultType);
(*c.astOriginalCallTypes)[c.astFragment] = *mm;
(*c.astOverloadResolvedTypes)[c.astFragment] = *instantiatedMm;
return true;
}
}
// If there's no metamethod available, fall back to primitive behavior.
}
switch (c.op)
{
// For arithmetic operators, if the LHS is a number, the RHS must be a
// number as well. The result will also be a number.
case AstExprBinary::Op::Add:
case AstExprBinary::Op::Sub:
case AstExprBinary::Op::Mul:
case AstExprBinary::Op::Div:
case AstExprBinary::Op::Pow:
case AstExprBinary::Op::Mod:
{
const NormalizedType* normLeftTy = normalizer->normalize(leftType);
if (hasTypeInIntersection<FreeType>(leftType) && force)
asMutable(leftType)->ty.emplace<BoundType>(anyPresent ? builtinTypes->anyType : builtinTypes->numberType);
// We want to check if the left type has tops because `any` is a valid type for the lhs
if (normLeftTy && (normLeftTy->isExactlyNumber() || get<AnyType>(normLeftTy->tops)))
{
unify(leftType, rightType, constraint->scope);
asMutable(resultType)->ty.emplace<BoundType>(anyPresent ? builtinTypes->anyType : leftType);
unblock(resultType);
return true;
}
else if (get<NeverType>(leftType) || get<NeverType>(rightType))
{
unify(leftType, rightType, constraint->scope);
asMutable(resultType)->ty.emplace<BoundType>(builtinTypes->neverType);
unblock(resultType);
return true;
}
break;
}
// For concatenation, if the LHS is a string, the RHS must be a string as
// well. The result will also be a string.
case AstExprBinary::Op::Concat:
{
if (hasTypeInIntersection<FreeType>(leftType) && force)
asMutable(leftType)->ty.emplace<BoundType>(anyPresent ? builtinTypes->anyType : builtinTypes->stringType);
const NormalizedType* leftNormTy = normalizer->normalize(leftType);
if (leftNormTy && leftNormTy->isSubtypeOfString())
{
unify(leftType, rightType, constraint->scope);
asMutable(resultType)->ty.emplace<BoundType>(anyPresent ? builtinTypes->anyType : leftType);
unblock(resultType);
return true;
}
else if (get<NeverType>(leftType) || get<NeverType>(rightType))
{
unify(leftType, rightType, constraint->scope);
asMutable(resultType)->ty.emplace<BoundType>(builtinTypes->neverType);
unblock(resultType);
return true;
}
break;
}
// Inexact comparisons require that the types be both numbers or both
// strings, and evaluate to a boolean.
case AstExprBinary::Op::CompareGe:
case AstExprBinary::Op::CompareGt:
case AstExprBinary::Op::CompareLe:
case AstExprBinary::Op::CompareLt:
{
const NormalizedType* lt = normalizer->normalize(leftType);
const NormalizedType* rt = normalizer->normalize(rightType);
// If the lhs is any, comparisons should be valid.
if (lt && rt && (lt->isExactlyNumber() || get<AnyType>(lt->tops)) && rt->isExactlyNumber())
{
asMutable(resultType)->ty.emplace<BoundType>(builtinTypes->booleanType);
unblock(resultType);
return true;
}
if (lt && rt && (lt->isSubtypeOfString() || get<AnyType>(lt->tops)) && rt->isSubtypeOfString())
{
asMutable(resultType)->ty.emplace<BoundType>(builtinTypes->booleanType);
unblock(resultType);
return true;
}
if (get<NeverType>(leftType) || get<NeverType>(rightType))
{
asMutable(resultType)->ty.emplace<BoundType>(builtinTypes->booleanType);
unblock(resultType);
return true;
}
break;
}
// == and ~= always evaluate to a boolean, and impose no other constraints
// on their parameters.
case AstExprBinary::Op::CompareEq:
case AstExprBinary::Op::CompareNe:
asMutable(resultType)->ty.emplace<BoundType>(builtinTypes->booleanType);
unblock(resultType);
return true;
// And evalutes to a boolean if the LHS is falsey, and the RHS type if LHS is
// truthy.
case AstExprBinary::Op::And:
{
TypeId leftFilteredTy = simplifyIntersection(builtinTypes, arena, leftType, builtinTypes->falsyType).result;
asMutable(resultType)->ty.emplace<BoundType>(simplifyUnion(builtinTypes, arena, rightType, leftFilteredTy).result);
unblock(resultType);
return true;
}
// Or evaluates to the LHS type if the LHS is truthy, and the RHS type if
// LHS is falsey.
case AstExprBinary::Op::Or:
{
TypeId leftFilteredTy = simplifyIntersection(builtinTypes, arena, leftType, builtinTypes->truthyType).result;
asMutable(resultType)->ty.emplace<BoundType>(simplifyUnion(builtinTypes, arena, rightType, leftFilteredTy).result);
unblock(resultType);
return true;
}
default:
iceReporter.ice("Unhandled AstExprBinary::Op for binary operation", constraint->location);
break;
}
// We failed to either evaluate a metamethod or invoke primitive behavior.
unify(leftType, errorRecoveryType(), constraint->scope);
unify(rightType, errorRecoveryType(), constraint->scope);
asMutable(resultType)->ty.emplace<BoundType>(errorRecoveryType());
unblock(resultType);
return true;
}
bool ConstraintSolver::tryDispatch(const IterableConstraint& c, NotNull<const Constraint> constraint, bool force)
{
/*
* for .. in loops can play out in a bunch of different ways depending on
* the shape of iteratee.
*
* iteratee might be:
* * (nextFn)
* * (nextFn, table)
* * (nextFn, table, firstIndex)
* * table with a metatable and __index
* * table with a metatable and __call but no __index (if the metatable has
* both, __index takes precedence)
* * table with an indexer but no __index or __call (or no metatable)
*
* To dispatch this constraint, we need first to know enough about iteratee
* to figure out which of the above shapes we are actually working with.
*
* If `force` is true and we still do not know, we must flag a warning. Type
* families are the fix for this.
*
* Since we need to know all of this stuff about the types of the iteratee,
* we have no choice but for ConstraintSolver to also be the thing that
* applies constraints to the types of the iterators.
*/
auto block_ = [&](auto&& t) {
if (force)
{
// If we haven't figured out the type of the iteratee by now,
// there's nothing we can do.
return true;
}
block(t, constraint);
return false;
};
auto [iteratorTypes, iteratorTail] = flatten(c.iterator);
if (iteratorTail && isBlocked(*iteratorTail))
return block_(*iteratorTail);
{
bool blocked = false;
for (TypeId t : iteratorTypes)
{
if (isBlocked(t))
{
block(t, constraint);
blocked = true;
}
}
if (blocked)
return false;
}
if (0 == iteratorTypes.size())
{
Anyification anyify{arena, constraint->scope, builtinTypes, &iceReporter, errorRecoveryType(), errorRecoveryTypePack()};
std::optional<TypePackId> anyified = anyify.substitute(c.variables);
LUAU_ASSERT(anyified);
unify(*anyified, c.variables, constraint->scope);
return true;
}
TypeId nextTy = follow(iteratorTypes[0]);
if (get<FreeType>(nextTy))
return block_(nextTy);
if (get<FunctionType>(nextTy))
{
TypeId tableTy = builtinTypes->nilType;
if (iteratorTypes.size() >= 2)
tableTy = iteratorTypes[1];
TypeId firstIndexTy = builtinTypes->nilType;
if (iteratorTypes.size() >= 3)
firstIndexTy = iteratorTypes[2];
return tryDispatchIterableFunction(nextTy, tableTy, firstIndexTy, c, constraint, force);
}
else
return tryDispatchIterableTable(iteratorTypes[0], c, constraint, force);
return true;
}
bool ConstraintSolver::tryDispatch(const NameConstraint& c, NotNull<const Constraint> constraint)
{
if (isBlocked(c.namedType))
return block(c.namedType, constraint);
TypeId target = follow(c.namedType);
if (target->persistent || target->owningArena != arena)
return true;
if (TableType* ttv = getMutable<TableType>(target))
{
if (c.synthetic && !ttv->name)
ttv->syntheticName = c.name;
else
{
ttv->name = c.name;
ttv->instantiatedTypeParams = c.typeParameters;
ttv->instantiatedTypePackParams = c.typePackParameters;
}
}
else if (MetatableType* mtv = getMutable<MetatableType>(target))
mtv->syntheticName = c.name;
else if (get<IntersectionType>(target) || get<UnionType>(target))
{
// nothing (yet)
}
else
return block(c.namedType, constraint);
return true;
}
struct InfiniteTypeFinder : TypeOnceVisitor
{
ConstraintSolver* solver;
const InstantiationSignature& signature;
NotNull<Scope> scope;
bool foundInfiniteType = false;
explicit InfiniteTypeFinder(ConstraintSolver* solver, const InstantiationSignature& signature, NotNull<Scope> scope)
: solver(solver)
, signature(signature)
, scope(scope)
{
}
bool visit(TypeId ty, const PendingExpansionType& petv) override
{
std::optional<TypeFun> tf =
(petv.prefix) ? scope->lookupImportedType(petv.prefix->value, petv.name.value) : scope->lookupType(petv.name.value);
if (!tf.has_value())
return true;
auto [typeArguments, packArguments] = saturateArguments(solver->arena, solver->builtinTypes, *tf, petv.typeArguments, petv.packArguments);
if (follow(tf->type) == follow(signature.fn.type) && (signature.arguments != typeArguments || signature.packArguments != packArguments))
{
foundInfiniteType = true;
return false;
}
return true;
}
};
bool ConstraintSolver::tryDispatch(const TypeAliasExpansionConstraint& c, NotNull<const Constraint> constraint)
{
const PendingExpansionType* petv = get<PendingExpansionType>(follow(c.target));
if (!petv)
{
unblock(c.target);
return true;
}
auto bindResult = [this, &c](TypeId result) {
LUAU_ASSERT(get<PendingExpansionType>(c.target));
asMutable(c.target)->ty.emplace<BoundType>(result);
unblock(c.target);
};
std::optional<TypeFun> tf = (petv->prefix) ? constraint->scope->lookupImportedType(petv->prefix->value, petv->name.value)
: constraint->scope->lookupType(petv->name.value);
if (!tf.has_value())
{
reportError(UnknownSymbol{petv->name.value, UnknownSymbol::Context::Type}, constraint->location);
bindResult(errorRecoveryType());
return true;
}
// If there are no parameters to the type function we can just use the type
// directly.
if (tf->typeParams.empty() && tf->typePackParams.empty())
{
bindResult(tf->type);
return true;
}
auto [typeArguments, packArguments] = saturateArguments(arena, builtinTypes, *tf, petv->typeArguments, petv->packArguments);
bool sameTypes = std::equal(typeArguments.begin(), typeArguments.end(), tf->typeParams.begin(), tf->typeParams.end(), [](auto&& itp, auto&& p) {
return itp == p.ty;
});
bool samePacks =
std::equal(packArguments.begin(), packArguments.end(), tf->typePackParams.begin(), tf->typePackParams.end(), [](auto&& itp, auto&& p) {
return itp == p.tp;
});
// If we're instantiating the type with its generic saturatedTypeArguments we are
// performing the identity substitution. We can just short-circuit and bind
// to the TypeFun's type.
if (sameTypes && samePacks)
{
bindResult(tf->type);
return true;
}
InstantiationSignature signature{
*tf,
typeArguments,
packArguments,
};
// If we use the same signature, we don't need to bother trying to
// instantiate the alias again, since the instantiation should be
// deterministic.
if (TypeId* cached = instantiatedAliases.find(signature))
{
bindResult(*cached);
return true;
}
// In order to prevent infinite types from being expanded and causing us to
// cycle infinitely, we need to scan the type function for cases where we
// expand the same alias with different type saturatedTypeArguments. See
// https://github.com/Roblox/luau/pull/68 for the RFC responsible for this.
// This is a little nicer than using a recursion limit because we can catch
// the infinite expansion before actually trying to expand it.
InfiniteTypeFinder itf{this, signature, constraint->scope};
itf.traverse(tf->type);
if (itf.foundInfiniteType)
{
// TODO (CLI-56761): Report an error.
bindResult(errorRecoveryType());
reportError(GenericError{"Recursive type being used with different parameters"}, constraint->location);
return true;
}
ApplyTypeFunction applyTypeFunction{arena};
for (size_t i = 0; i < typeArguments.size(); ++i)
{
applyTypeFunction.typeArguments[tf->typeParams[i].ty] = typeArguments[i];
}
for (size_t i = 0; i < packArguments.size(); ++i)
{
applyTypeFunction.typePackArguments[tf->typePackParams[i].tp] = packArguments[i];
}
std::optional<TypeId> maybeInstantiated = applyTypeFunction.substitute(tf->type);
// Note that ApplyTypeFunction::encounteredForwardedType is never set in
// DCR, because we do not use free types for forward-declared generic
// aliases.
if (!maybeInstantiated.has_value())
{
// TODO (CLI-56761): Report an error.
bindResult(errorRecoveryType());
return true;
}
TypeId instantiated = *maybeInstantiated;
TypeId target = follow(instantiated);
// The application is not recursive, so we need to queue up application of
// any child type function instantiations within the result in order for it
// to be complete.
InstantiationQueuer queuer{constraint->scope, constraint->location, this};
queuer.traverse(target);
if (target->persistent || target->owningArena != arena)
{
bindResult(target);
return true;
}
// Type function application will happily give us the exact same type if
// there are e.g. generic saturatedTypeArguments that go unused.
bool needsClone = follow(tf->type) == target;
// Only tables have the properties we're trying to set.
TableType* ttv = getMutableTableType(target);
if (ttv)
{
if (needsClone)
{
// Substitution::clone is a shallow clone. If this is a
// metatable type, we want to mutate its table, so we need to
// explicitly clone that table as well. If we don't, we will
// mutate another module's type surface and cause a
// use-after-free.
if (get<MetatableType>(target))
{
instantiated = applyTypeFunction.clone(target);
MetatableType* mtv = getMutable<MetatableType>(instantiated);
mtv->table = applyTypeFunction.clone(mtv->table);
ttv = getMutable<TableType>(mtv->table);
}
else if (get<TableType>(target))
{
instantiated = applyTypeFunction.clone(target);
ttv = getMutable<TableType>(instantiated);
}
target = follow(instantiated);
}
ttv->instantiatedTypeParams = typeArguments;
ttv->instantiatedTypePackParams = packArguments;
// TODO: Fill in definitionModuleName.
}
bindResult(target);
instantiatedAliases[signature] = target;
return true;
}
bool ConstraintSolver::tryDispatch(const FunctionCallConstraint& c, NotNull<const Constraint> constraint)
{
TypeId fn = follow(c.fn);
TypePackId argsPack = follow(c.argsPack);
TypePackId result = follow(c.result);
if (isBlocked(fn))
{
return block(c.fn, constraint);
}
auto collapse = [](const auto* t) -> std::optional<TypeId> {
auto it = begin(t);
auto endIt = end(t);
LUAU_ASSERT(it != endIt);
TypeId fst = follow(*it);
while (it != endIt)
{
if (follow(*it) != fst)
return std::nullopt;
++it;
}
return fst;
};
// Sometimes the `fn` type is a union/intersection, but whose constituents are all the same pointer.
if (auto ut = get<UnionType>(fn))
fn = collapse(ut).value_or(fn);
else if (auto it = get<IntersectionType>(fn))
fn = collapse(it).value_or(fn);
if (c.callSite)
(*c.astOriginalCallTypes)[c.callSite] = fn;
// We don't support magic __call metamethods.
if (std::optional<TypeId> callMm = findMetatableEntry(builtinTypes, errors, fn, "__call", constraint->location))
{
std::vector<TypeId> args{fn};
for (TypeId arg : c.argsPack)
args.push_back(arg);
argsPack = arena->addTypePack(TypePack{args, {}});
fn = *callMm;
asMutable(c.result)->ty.emplace<FreeTypePack>(constraint->scope);
}
else
{
const FunctionType* ftv = get<FunctionType>(fn);
bool usedMagic = false;
if (ftv)
{
if (ftv->dcrMagicFunction)
usedMagic = ftv->dcrMagicFunction(MagicFunctionCallContext{NotNull(this), c.callSite, c.argsPack, result});
if (ftv->dcrMagicRefinement)
ftv->dcrMagicRefinement(MagicRefinementContext{constraint->scope, c.callSite, c.discriminantTypes});
}
if (!usedMagic)
asMutable(c.result)->ty.emplace<FreeTypePack>(constraint->scope);
}
for (std::optional<TypeId> ty : c.discriminantTypes)
{
if (!ty || !isBlocked(*ty))
continue;
// We use `any` here because the discriminant type may be pointed at by both branches,
// where the discriminant type is not negated, and the other where it is negated, i.e.
// `unknown ~ unknown` and `~unknown ~ never`, so `T & unknown ~ T` and `T & ~unknown ~ never`
// v.s.
// `any ~ any` and `~any ~ any`, so `T & any ~ T` and `T & ~any ~ T`
//
// In practice, users cannot negate `any`, so this is an implementation detail we can always change.
*asMutable(follow(*ty)) = BoundType{builtinTypes->anyType};
}
TypeId inferredTy = arena->addType(FunctionType{TypeLevel{}, constraint->scope.get(), argsPack, c.result});
const NormalizedType* normFn = normalizer->normalize(fn);
if (!normFn)
{
reportError(UnificationTooComplex{}, constraint->location);
return true;
}
// TODO: It would be nice to not need to convert the normalized type back to
// an intersection and flatten it.
TypeId normFnTy = normalizer->typeFromNormal(*normFn);
std::vector<TypeId> overloads = flattenIntersection(normFnTy);
Instantiation inst(TxnLog::empty(), arena, TypeLevel{}, constraint->scope);
std::vector<TypeId> arityMatchingOverloads;
std::optional<TxnLog> bestOverloadLog;
for (TypeId overload : overloads)
{
overload = follow(overload);
std::optional<TypeId> instantiated = inst.substitute(overload);
if (!instantiated.has_value())
{
reportError(UnificationTooComplex{}, constraint->location);
return true;
}
Unifier u{normalizer, constraint->scope, Location{}, Covariant};
u.enableScopeTests();
u.tryUnify(*instantiated, inferredTy, /* isFunctionCall */ true);
if (!u.blockedTypes.empty() || !u.blockedTypePacks.empty())
{
for (TypeId bt : u.blockedTypes)
block(bt, constraint);
for (TypePackId btp : u.blockedTypePacks)
block(btp, constraint);
return false;
}
if (const auto& e = hasUnificationTooComplex(u.errors))
reportError(*e);
const auto& e = hasCountMismatch(u.errors);
bool areArgumentsCompatible = (!e || get<CountMismatch>(*e)->context != CountMismatch::Context::Arg) && get<FunctionType>(*instantiated);
if (areArgumentsCompatible)
arityMatchingOverloads.push_back(*instantiated);
if (u.errors.empty())
{
if (c.callSite)
(*c.astOverloadResolvedTypes)[c.callSite] = *instantiated;
// This overload has no errors, so override the bestOverloadLog and use this one.
bestOverloadLog = std::move(u.log);
break;
}
else if (areArgumentsCompatible && !bestOverloadLog)
{
// This overload is erroneous. Replace its inferences with `any` iff there isn't already a TxnLog.
bestOverloadLog = std::move(u.log);
}
}
if (arityMatchingOverloads.size() == 1 && c.callSite)
{
// In the name of better error messages in the type checker, we provide
// it with an instantiated function signature that matched arity, but
// not the requisite subtyping requirements. This makes errors better in
// cases where only one overload fit from an arity perspective.
(*c.astOverloadResolvedTypes)[c.callSite] = arityMatchingOverloads.at(0);
}
// We didn't find any overload that were a viable candidate, so replace the inferences with `any`.
if (!bestOverloadLog)
{
Unifier u{normalizer, constraint->scope, Location{}, Covariant};
u.enableScopeTests();
u.tryUnify(inferredTy, builtinTypes->anyType);
u.tryUnify(fn, builtinTypes->anyType);
bestOverloadLog = std::move(u.log);
}
const auto [changedTypes, changedPacks] = bestOverloadLog->getChanges();
bestOverloadLog->commit();
unblock(changedTypes);
unblock(changedPacks);
unblock(c.result);
InstantiationQueuer queuer{constraint->scope, constraint->location, this};
queuer.traverse(fn);
queuer.traverse(inferredTy);
return true;
}
bool ConstraintSolver::tryDispatch(const PrimitiveTypeConstraint& c, NotNull<const Constraint> constraint)
{
TypeId expectedType = follow(c.expectedType);
if (isBlocked(expectedType) || get<PendingExpansionType>(expectedType))
return block(expectedType, constraint);
LUAU_ASSERT(get<BlockedType>(c.resultType));
TypeId bindTo = maybeSingleton(expectedType) ? c.singletonType : c.multitonType;
asMutable(c.resultType)->ty.emplace<BoundType>(bindTo);
unblock(c.resultType);
return true;
}
bool ConstraintSolver::tryDispatch(const HasPropConstraint& c, NotNull<const Constraint> constraint)
{
TypeId subjectType = follow(c.subjectType);
LUAU_ASSERT(get<BlockedType>(c.resultType));
if (isBlocked(subjectType) || get<PendingExpansionType>(subjectType))
return block(subjectType, constraint);
if (get<FreeType>(subjectType))
{
TableType& ttv = asMutable(subjectType)->ty.emplace<TableType>(TableState::Free, TypeLevel{}, constraint->scope);
ttv.props[c.prop] = Property{c.resultType};
asMutable(c.resultType)->ty.emplace<FreeType>(constraint->scope);
unblock(c.resultType);
return true;
}
auto [blocked, result] = lookupTableProp(subjectType, c.prop, c.suppressSimplification);
if (!blocked.empty())
{
for (TypeId blocked : blocked)
block(blocked, constraint);
return false;
}
asMutable(c.resultType)->ty.emplace<BoundType>(result.value_or(builtinTypes->anyType));
unblock(c.resultType);
return true;
}
static bool isUnsealedTable(TypeId ty)
{
ty = follow(ty);
const TableType* ttv = get<TableType>(ty);
return ttv && ttv->state == TableState::Unsealed;
}
/**
* Given a path into a set of nested unsealed tables `ty`, insert a new property `replaceTy` as the leaf-most property.
*
* Fails and does nothing if every table along the way is not unsealed.
*
* Mutates the innermost table type in-place.
*/
static void updateTheTableType(
NotNull<BuiltinTypes> builtinTypes, NotNull<TypeArena> arena, TypeId ty, const std::vector<std::string>& path, TypeId replaceTy)
{
if (path.empty())
return;
// First walk the path and ensure that it's unsealed tables all the way
// to the end.
{
TypeId t = ty;
for (size_t i = 0; i < path.size() - 1; ++i)
{
if (!isUnsealedTable(t))
return;
const TableType* tbl = get<TableType>(t);
auto it = tbl->props.find(path[i]);
if (it == tbl->props.end())
return;
t = follow(it->second.type());
}
// The last path segment should not be a property of the table at all.
// We are not changing property types. We are only admitting this one
// new property to be appended.
if (!isUnsealedTable(t))
return;
const TableType* tbl = get<TableType>(t);
if (0 != tbl->props.count(path.back()))
return;
}
TypeId t = ty;
ErrorVec dummy;
for (size_t i = 0; i < path.size() - 1; ++i)
{
auto propTy = findTablePropertyRespectingMeta(builtinTypes, dummy, t, path[i], Location{});
dummy.clear();
if (!propTy)
return;
t = *propTy;
}
const std::string& lastSegment = path.back();
t = follow(t);
TableType* tt = getMutable<TableType>(t);
if (auto mt = get<MetatableType>(t))
tt = getMutable<TableType>(mt->table);
if (!tt)
return;
tt->props[lastSegment].setType(replaceTy);
}
bool ConstraintSolver::tryDispatch(const SetPropConstraint& c, NotNull<const Constraint> constraint, bool force)
{
TypeId subjectType = follow(c.subjectType);
if (isBlocked(subjectType))
return block(subjectType, constraint);
if (!force && get<FreeType>(subjectType))
return block(subjectType, constraint);
std::optional<TypeId> existingPropType = subjectType;
for (const std::string& segment : c.path)
{
if (!existingPropType)
break;
auto [blocked, result] = lookupTableProp(*existingPropType, segment);
if (!blocked.empty())
{
for (TypeId blocked : blocked)
block(blocked, constraint);
return false;
}
existingPropType = result;
}
auto bind = [](TypeId a, TypeId b) {
asMutable(a)->ty.emplace<BoundType>(b);
};
if (existingPropType)
{
if (!isBlocked(c.propType))
unify(c.propType, *existingPropType, constraint->scope);
bind(c.resultType, c.subjectType);
unblock(c.resultType);
return true;
}
if (auto mt = get<MetatableType>(subjectType))
subjectType = follow(mt->table);
if (get<FreeType>(subjectType))
{
TypeId ty = arena->freshType(constraint->scope);
// Mint a chain of free tables per c.path
for (auto it = rbegin(c.path); it != rend(c.path); ++it)
{
TableType t{TableState::Free, TypeLevel{}, constraint->scope};
t.props[*it] = {ty};
ty = arena->addType(std::move(t));
}
LUAU_ASSERT(ty);
bind(subjectType, ty);
if (follow(c.resultType) != follow(ty))
bind(c.resultType, ty);
unblock(subjectType);
unblock(c.resultType);
return true;
}
else if (auto ttv = getMutable<TableType>(subjectType))
{
if (ttv->state == TableState::Free)
{
LUAU_ASSERT(!subjectType->persistent);
ttv->props[c.path[0]] = Property{c.propType};
bind(c.resultType, c.subjectType);
unblock(c.resultType);
return true;
}
else if (ttv->state == TableState::Unsealed)
{
LUAU_ASSERT(!subjectType->persistent);
updateTheTableType(builtinTypes, NotNull{arena}, subjectType, c.path, c.propType);
bind(c.resultType, c.subjectType);
unblock(subjectType);
unblock(c.resultType);
return true;
}
else
{
bind(c.resultType, subjectType);
unblock(c.resultType);
return true;
}
}
else
{
// Other kinds of types don't change shape when properties are assigned
// to them. (if they allow properties at all!)
bind(c.resultType, subjectType);
unblock(c.resultType);
return true;
}
}
bool ConstraintSolver::tryDispatch(const SetIndexerConstraint& c, NotNull<const Constraint> constraint, bool force)
{
TypeId subjectType = follow(c.subjectType);
if (isBlocked(subjectType))
return block(subjectType, constraint);
if (auto ft = get<FreeType>(subjectType))
{
Scope* scope = ft->scope;
TableType* tt = &asMutable(subjectType)->ty.emplace<TableType>(TableState::Free, TypeLevel{}, scope);
tt->indexer = TableIndexer{c.indexType, c.propType};
asMutable(c.resultType)->ty.emplace<BoundType>(subjectType);
asMutable(c.propType)->ty.emplace<FreeType>(scope);
unblock(c.propType);
unblock(c.resultType);
return true;
}
else if (auto tt = get<TableType>(subjectType))
{
if (tt->indexer)
{
// TODO This probably has to be invariant.
unify(c.indexType, tt->indexer->indexType, constraint->scope);
asMutable(c.propType)->ty.emplace<BoundType>(tt->indexer->indexResultType);
asMutable(c.resultType)->ty.emplace<BoundType>(subjectType);
unblock(c.propType);
unblock(c.resultType);
return true;
}
else if (tt->state == TableState::Free || tt->state == TableState::Unsealed)
{
TypeId promotedIndexTy = arena->freshType(tt->scope);
unify(c.indexType, promotedIndexTy, constraint->scope);
auto mtt = getMutable<TableType>(subjectType);
mtt->indexer = TableIndexer{promotedIndexTy, c.propType};
asMutable(c.propType)->ty.emplace<FreeType>(tt->scope);
asMutable(c.resultType)->ty.emplace<BoundType>(subjectType);
unblock(c.propType);
unblock(c.resultType);
return true;
}
// Do not augment sealed or generic tables that lack indexers
}
asMutable(c.propType)->ty.emplace<BoundType>(builtinTypes->errorRecoveryType());
asMutable(c.resultType)->ty.emplace<BoundType>(builtinTypes->errorRecoveryType());
unblock(c.propType);
unblock(c.resultType);
return true;
}
bool ConstraintSolver::tryDispatch(const SingletonOrTopTypeConstraint& c, NotNull<const Constraint> constraint)
{
if (isBlocked(c.discriminantType))
return false;
TypeId followed = follow(c.discriminantType);
// `nil` is a singleton type too! There's only one value of type `nil`.
if (c.negated && (get<SingletonType>(followed) || isNil(followed)))
*asMutable(c.resultType) = NegationType{c.discriminantType};
else if (!c.negated && get<SingletonType>(followed))
*asMutable(c.resultType) = BoundType{c.discriminantType};
else
*asMutable(c.resultType) = BoundType{builtinTypes->anyType};
unblock(c.resultType);
return true;
}
bool ConstraintSolver::tryDispatch(const UnpackConstraint& c, NotNull<const Constraint> constraint)
{
TypePackId sourcePack = follow(c.sourcePack);
TypePackId resultPack = follow(c.resultPack);
if (isBlocked(sourcePack))
return block(sourcePack, constraint);
if (isBlocked(resultPack))
{
asMutable(resultPack)->ty.emplace<BoundTypePack>(sourcePack);
unblock(resultPack);
return true;
}
TypePack srcPack = extendTypePack(*arena, builtinTypes, sourcePack, size(resultPack));
auto destIter = begin(resultPack);
auto destEnd = end(resultPack);
size_t i = 0;
while (destIter != destEnd)
{
if (i >= srcPack.head.size())
break;
TypeId srcTy = follow(srcPack.head[i]);
if (isBlocked(*destIter))
{
if (follow(srcTy) == *destIter)
{
// Cyclic type dependency. (????)
asMutable(*destIter)->ty.emplace<FreeType>(constraint->scope);
}
else
asMutable(*destIter)->ty.emplace<BoundType>(srcTy);
unblock(*destIter);
}
else
unify(*destIter, srcTy, constraint->scope);
++destIter;
++i;
}
// We know that resultPack does not have a tail, but we don't know if
// sourcePack is long enough to fill every value. Replace every remaining
// result TypeId with the error recovery type.
while (destIter != destEnd)
{
if (isBlocked(*destIter))
{
asMutable(*destIter)->ty.emplace<BoundType>(builtinTypes->errorRecoveryType());
unblock(*destIter);
}
++destIter;
}
return true;
}
namespace
{
/*
* Search for types that prevent us from being ready to dispatch a particular
* RefineConstraint.
*/
struct FindRefineConstraintBlockers : TypeOnceVisitor
{
std::unordered_set<TypeId> found;
bool visit(TypeId ty, const BlockedType&) override
{
found.insert(ty);
return false;
}
bool visit(TypeId ty, const PendingExpansionType&) override
{
found.insert(ty);
return false;
}
bool visit(TypeId ty, const ClassType&) override
{
return false;
}
};
} // namespace
static bool isNegatedAny(TypeId ty)
{
ty = follow(ty);
const NegationType* nt = get<NegationType>(ty);
if (!nt)
return false;
TypeId negatedTy = follow(nt->ty);
return bool(get<AnyType>(negatedTy));
}
bool ConstraintSolver::tryDispatch(const RefineConstraint& c, NotNull<const Constraint> constraint, bool force)
{
if (isBlocked(c.discriminant))
return block(c.discriminant, constraint);
FindRefineConstraintBlockers fbt;
fbt.traverse(c.discriminant);
if (!fbt.found.empty())
{
bool foundOne = false;
for (TypeId blocked : fbt.found)
{
if (blocked == c.type)
continue;
block(blocked, constraint);
foundOne = true;
}
if (foundOne)
return false;
}
/* HACK: Refinements sometimes produce a type T & ~any under the assumption
* that ~any is the same as any. This is so so weird, but refinements needs
* some way to say "I may refine this, but I'm not sure."
*
* It does this by refining on a blocked type and deferring the decision
* until it is unblocked.
*
* Refinements also get negated, so we wind up with types like T & ~*blocked*
*
* We need to treat T & ~any as T in this case.
*/
if (c.mode == RefineConstraint::Intersection && isNegatedAny(c.discriminant))
{
asMutable(c.resultType)->ty.emplace<BoundType>(c.type);
unblock(c.resultType);
return true;
}
const TypeId type = follow(c.type);
LUAU_ASSERT(get<BlockedType>(c.resultType));
if (type == c.resultType)
{
/*
* Sometimes, we get a constraint of the form
*
* *blocked-N* ~ refine *blocked-N* & U
*
* The constraint essentially states that a particular type is a
* refinement of itself. This is weird and I think vacuous.
*
* I *believe* it is safe to replace the result with a fresh type that
* is constrained by U. We effect this by minting a fresh type for the
* result when U = any, else we bind the result to whatever discriminant
* was offered.
*/
if (get<AnyType>(follow(c.discriminant)))
asMutable(c.resultType)->ty.emplace<FreeType>(constraint->scope);
else
asMutable(c.resultType)->ty.emplace<BoundType>(c.discriminant);
unblock(c.resultType);
return true;
}
auto [result, blockedTypes] = c.mode == RefineConstraint::Intersection ? simplifyIntersection(builtinTypes, NotNull{arena}, type, c.discriminant)
: simplifyUnion(builtinTypes, NotNull{arena}, type, c.discriminant);
if (!force && !blockedTypes.empty())
return block(blockedTypes, constraint);
asMutable(c.resultType)->ty.emplace<BoundType>(result);
unblock(c.resultType);
return true;
}
bool ConstraintSolver::tryDispatch(const ReduceConstraint& c, NotNull<const Constraint> constraint, bool force)
{
TypeId ty = follow(c.ty);
FamilyGraphReductionResult result =
reduceFamilies(ty, constraint->location, NotNull{arena}, builtinTypes, constraint->scope, normalizer, nullptr, force);
for (TypeId r : result.reducedTypes)
unblock(r);
for (TypePackId r : result.reducedPacks)
unblock(r);
if (force)
return true;
for (TypeId b : result.blockedTypes)
block(b, constraint);
for (TypePackId b : result.blockedPacks)
block(b, constraint);
return result.blockedTypes.empty() && result.blockedPacks.empty();
}
bool ConstraintSolver::tryDispatch(const ReducePackConstraint& c, NotNull<const Constraint> constraint, bool force)
{
TypePackId tp = follow(c.tp);
FamilyGraphReductionResult result =
reduceFamilies(tp, constraint->location, NotNull{arena}, builtinTypes, constraint->scope, normalizer, nullptr, force);
for (TypeId r : result.reducedTypes)
unblock(r);
for (TypePackId r : result.reducedPacks)
unblock(r);
if (force)
return true;
for (TypeId b : result.blockedTypes)
block(b, constraint);
for (TypePackId b : result.blockedPacks)
block(b, constraint);
return result.blockedTypes.empty() && result.blockedPacks.empty();
}
bool ConstraintSolver::tryDispatchIterableTable(TypeId iteratorTy, const IterableConstraint& c, NotNull<const Constraint> constraint, bool force)
{
auto block_ = [&](auto&& t) {
if (force)
{
// TODO: I believe it is the case that, if we are asked to force
// this constraint, then we can do nothing but fail. I'd like to
// find a code sample that gets here.
LUAU_ASSERT(false);
}
else
block(t, constraint);
return false;
};
// We may have to block here if we don't know what the iteratee type is,
// if it's a free table, if we don't know it has a metatable, and so on.
iteratorTy = follow(iteratorTy);
if (get<FreeType>(iteratorTy))
return block_(iteratorTy);
auto anyify = [&](auto ty) {
Anyification anyify{arena, constraint->scope, builtinTypes, &iceReporter, builtinTypes->anyType, builtinTypes->anyTypePack};
std::optional anyified = anyify.substitute(ty);
if (!anyified)
reportError(CodeTooComplex{}, constraint->location);
else
unify(*anyified, ty, constraint->scope);
};
auto errorify = [&](auto ty) {
Anyification anyify{arena, constraint->scope, builtinTypes, &iceReporter, errorRecoveryType(), errorRecoveryTypePack()};
std::optional errorified = anyify.substitute(ty);
if (!errorified)
reportError(CodeTooComplex{}, constraint->location);
else
unify(*errorified, ty, constraint->scope);
};
auto neverify = [&](auto ty) {
Anyification anyify{arena, constraint->scope, builtinTypes, &iceReporter, builtinTypes->neverType, builtinTypes->neverTypePack};
std::optional neverified = anyify.substitute(ty);
if (!neverified)
reportError(CodeTooComplex{}, constraint->location);
else
unify(*neverified, ty, constraint->scope);
};
if (get<AnyType>(iteratorTy))
{
anyify(c.variables);
return true;
}
if (get<ErrorType>(iteratorTy))
{
errorify(c.variables);
return true;
}
if (get<NeverType>(iteratorTy))
{
neverify(c.variables);
return true;
}
// Irksome: I don't think we have any way to guarantee that this table
// type never has a metatable.
if (auto iteratorTable = get<TableType>(iteratorTy))
{
/*
* We try not to dispatch IterableConstraints over free tables because
* it's possible that there are other constraints on the table that will
* clarify what we should do.
*
* We should eventually introduce a type family to talk about iteration.
*/
if (iteratorTable->state == TableState::Free && !force)
return block(iteratorTy, constraint);
if (iteratorTable->indexer)
{
TypePackId expectedVariablePack = arena->addTypePack({iteratorTable->indexer->indexType, iteratorTable->indexer->indexResultType});
unify(c.variables, expectedVariablePack, constraint->scope);
}
else
errorify(c.variables);
}
else if (std::optional<TypeId> iterFn = findMetatableEntry(builtinTypes, errors, iteratorTy, "__iter", Location{}))
{
if (isBlocked(*iterFn))
{
return block(*iterFn, constraint);
}
Instantiation instantiation(TxnLog::empty(), arena, TypeLevel{}, constraint->scope);
if (std::optional<TypeId> instantiatedIterFn = instantiation.substitute(*iterFn))
{
if (auto iterFtv = get<FunctionType>(*instantiatedIterFn))
{
TypePackId expectedIterArgs = arena->addTypePack({iteratorTy});
unify(iterFtv->argTypes, expectedIterArgs, constraint->scope);
TypePack iterRets = extendTypePack(*arena, builtinTypes, iterFtv->retTypes, 2);
if (iterRets.head.size() < 1)
{
// We've done what we can; this will get reported as an
// error by the type checker.
return true;
}
TypeId nextFn = iterRets.head[0];
TypeId table = iterRets.head.size() == 2 ? iterRets.head[1] : arena->freshType(constraint->scope);
if (std::optional<TypeId> instantiatedNextFn = instantiation.substitute(nextFn))
{
const TypeId firstIndex = arena->freshType(constraint->scope);
// nextTy : (iteratorTy, indexTy?) -> (indexTy, valueTailTy...)
const TypePackId nextArgPack = arena->addTypePack({table, arena->addType(UnionType{{firstIndex, builtinTypes->nilType}})});
const TypePackId valueTailTy = arena->addTypePack(FreeTypePack{constraint->scope});
const TypePackId nextRetPack = arena->addTypePack(TypePack{{firstIndex}, valueTailTy});
const TypeId expectedNextTy = arena->addType(FunctionType{nextArgPack, nextRetPack});
unify(*instantiatedNextFn, expectedNextTy, constraint->scope);
pushConstraint(constraint->scope, constraint->location, PackSubtypeConstraint{c.variables, nextRetPack});
}
else
{
reportError(UnificationTooComplex{}, constraint->location);
}
}
else
{
// TODO: Support __call and function overloads (what does an overload even mean for this?)
}
}
else
{
reportError(UnificationTooComplex{}, constraint->location);
}
}
else if (auto iteratorMetatable = get<MetatableType>(iteratorTy))
{
TypeId metaTy = follow(iteratorMetatable->metatable);
if (get<FreeType>(metaTy))
return block_(metaTy);
LUAU_ASSERT(false);
}
else
errorify(c.variables);
return true;
}
bool ConstraintSolver::tryDispatchIterableFunction(
TypeId nextTy, TypeId tableTy, TypeId firstIndexTy, const IterableConstraint& c, NotNull<const Constraint> constraint, bool force)
{
// We need to know whether or not this type is nil or not.
// If we don't know, block and reschedule ourselves.
firstIndexTy = follow(firstIndexTy);
if (get<FreeType>(firstIndexTy))
{
if (force)
LUAU_ASSERT(false);
else
block(firstIndexTy, constraint);
return false;
}
TypeId firstIndex;
TypeId retIndex;
if (isNil(firstIndexTy) || isOptional(firstIndexTy))
{
firstIndex = arena->addType(UnionType{{arena->freshType(constraint->scope), builtinTypes->nilType}});
retIndex = firstIndex;
}
else
{
firstIndex = firstIndexTy;
retIndex = arena->addType(UnionType{{firstIndexTy, builtinTypes->nilType}});
}
// nextTy : (tableTy, indexTy?) -> (indexTy?, valueTailTy...)
const TypePackId nextArgPack = arena->addTypePack({tableTy, firstIndex});
const TypePackId valueTailTy = arena->addTypePack(FreeTypePack{constraint->scope});
const TypePackId nextRetPack = arena->addTypePack(TypePack{{retIndex}, valueTailTy});
const TypeId expectedNextTy = arena->addType(FunctionType{TypeLevel{}, constraint->scope, nextArgPack, nextRetPack});
ErrorVec errors = unify(nextTy, expectedNextTy, constraint->scope);
// if there are no errors from unifying the two, we can pass forward the expected type as our selected resolution.
if (errors.empty())
(*c.astOverloadResolvedTypes)[c.nextAstFragment] = expectedNextTy;
auto it = begin(nextRetPack);
std::vector<TypeId> modifiedNextRetHead;
// The first value is never nil in the context of the loop, even if it's nil
// in the next function's return type, because the loop will not advance if
// it's nil.
if (it != end(nextRetPack))
{
TypeId firstRet = *it;
TypeId modifiedFirstRet = stripNil(builtinTypes, *arena, firstRet);
modifiedNextRetHead.push_back(modifiedFirstRet);
++it;
}
for (; it != end(nextRetPack); ++it)
modifiedNextRetHead.push_back(*it);
TypePackId modifiedNextRetPack = arena->addTypePack(std::move(modifiedNextRetHead), it.tail());
auto psc = pushConstraint(constraint->scope, constraint->location, PackSubtypeConstraint{c.variables, modifiedNextRetPack});
inheritBlocks(constraint, psc);
return true;
}
std::pair<std::vector<TypeId>, std::optional<TypeId>> ConstraintSolver::lookupTableProp(
TypeId subjectType, const std::string& propName, bool suppressSimplification)
{
std::unordered_set<TypeId> seen;
return lookupTableProp(subjectType, propName, suppressSimplification, seen);
}
std::pair<std::vector<TypeId>, std::optional<TypeId>> ConstraintSolver::lookupTableProp(
TypeId subjectType, const std::string& propName, bool suppressSimplification, std::unordered_set<TypeId>& seen)
{
if (!seen.insert(subjectType).second)
return {};
subjectType = follow(subjectType);
if (isBlocked(subjectType))
return {{subjectType}, std::nullopt};
else if (get<AnyType>(subjectType) || get<NeverType>(subjectType))
{
return {{}, subjectType};
}
else if (auto ttv = getMutable<TableType>(subjectType))
{
if (auto prop = ttv->props.find(propName); prop != ttv->props.end())
return {{}, FFlag::DebugLuauReadWriteProperties ? prop->second.readType() : prop->second.type()};
else if (ttv->indexer && maybeString(ttv->indexer->indexType))
return {{}, ttv->indexer->indexResultType};
else if (ttv->state == TableState::Free)
{
TypeId result = arena->freshType(ttv->scope);
ttv->props[propName] = Property{result};
return {{}, result};
}
}
else if (auto mt = get<MetatableType>(subjectType))
{
auto [blocked, result] = lookupTableProp(mt->table, propName, suppressSimplification, seen);
if (!blocked.empty() || result)
return {blocked, result};
TypeId mtt = follow(mt->metatable);
if (get<BlockedType>(mtt))
return {{mtt}, std::nullopt};
else if (auto metatable = get<TableType>(mtt))
{
auto indexProp = metatable->props.find("__index");
if (indexProp == metatable->props.end())
return {{}, result};
// TODO: __index can be an overloaded function.
TypeId indexType = follow(indexProp->second.type());
if (auto ft = get<FunctionType>(indexType))
{
TypePack rets = extendTypePack(*arena, builtinTypes, ft->retTypes, 1);
if (1 == rets.head.size())
return {{}, rets.head[0]};
else
{
// This should probably be an error: We need the first result of the MT.__index method,
// but it returns 0 values. See CLI-68672
return {{}, builtinTypes->nilType};
}
}
else
return lookupTableProp(indexType, propName, suppressSimplification, seen);
}
}
else if (auto ct = get<ClassType>(subjectType))
{
if (auto p = lookupClassProp(ct, propName))
return {{}, p->type()};
if (ct->indexer)
{
return {{}, ct->indexer->indexResultType};
}
}
else if (auto pt = get<PrimitiveType>(subjectType); pt && pt->metatable)
{
const TableType* metatable = get<TableType>(follow(*pt->metatable));
LUAU_ASSERT(metatable);
auto indexProp = metatable->props.find("__index");
if (indexProp == metatable->props.end())
return {{}, std::nullopt};
return lookupTableProp(indexProp->second.type(), propName, suppressSimplification, seen);
}
else if (auto ft = get<FreeType>(subjectType))
{
Scope* scope = ft->scope;
TableType* tt = &asMutable(subjectType)->ty.emplace<TableType>();
tt->state = TableState::Free;
tt->scope = scope;
TypeId propType = arena->freshType(scope);
tt->props[propName] = Property{propType};
return {{}, propType};
}
else if (auto utv = get<UnionType>(subjectType))
{
std::vector<TypeId> blocked;
std::set<TypeId> options;
for (TypeId ty : utv)
{
auto [innerBlocked, innerResult] = lookupTableProp(ty, propName, suppressSimplification, seen);
blocked.insert(blocked.end(), innerBlocked.begin(), innerBlocked.end());
if (innerResult)
options.insert(*innerResult);
}
if (!blocked.empty())
return {blocked, std::nullopt};
if (options.empty())
return {{}, std::nullopt};
else if (options.size() == 1)
return {{}, *begin(options)};
else if (options.size() == 2 && !suppressSimplification)
{
TypeId one = *begin(options);
TypeId two = *(++begin(options));
return {{}, simplifyUnion(builtinTypes, arena, one, two).result};
}
else
return {{}, arena->addType(UnionType{std::vector<TypeId>(begin(options), end(options))})};
}
else if (auto itv = get<IntersectionType>(subjectType))
{
std::vector<TypeId> blocked;
std::set<TypeId> options;
for (TypeId ty : itv)
{
auto [innerBlocked, innerResult] = lookupTableProp(ty, propName, suppressSimplification, seen);
blocked.insert(blocked.end(), innerBlocked.begin(), innerBlocked.end());
if (innerResult)
options.insert(*innerResult);
}
if (!blocked.empty())
return {blocked, std::nullopt};
if (options.empty())
return {{}, std::nullopt};
else if (options.size() == 1)
return {{}, *begin(options)};
else if (options.size() == 2 && !suppressSimplification)
{
TypeId one = *begin(options);
TypeId two = *(++begin(options));
return {{}, simplifyIntersection(builtinTypes, arena, one, two).result};
}
else
return {{}, arena->addType(IntersectionType{std::vector<TypeId>(begin(options), end(options))})};
}
return {{}, std::nullopt};
}
static TypeId getErrorType(NotNull<BuiltinTypes> builtinTypes, TypeId)
{
return builtinTypes->errorRecoveryType();
}
static TypePackId getErrorType(NotNull<BuiltinTypes> builtinTypes, TypePackId)
{
return builtinTypes->errorRecoveryTypePack();
}
template<typename TID>
bool ConstraintSolver::tryUnify(NotNull<const Constraint> constraint, TID subTy, TID superTy)
{
Unifier u{normalizer, constraint->scope, constraint->location, Covariant};
u.enableScopeTests();
u.tryUnify(subTy, superTy);
if (!u.blockedTypes.empty() || !u.blockedTypePacks.empty())
{
for (TypeId bt : u.blockedTypes)
block(bt, constraint);
for (TypePackId btp : u.blockedTypePacks)
block(btp, constraint);
return false;
}
if (const auto& e = hasUnificationTooComplex(u.errors))
reportError(*e);
if (!u.errors.empty())
{
TID errorType = getErrorType(builtinTypes, TID{});
u.tryUnify(subTy, errorType);
u.tryUnify(superTy, errorType);
}
const auto [changedTypes, changedPacks] = u.log.getChanges();
u.log.commit();
unblock(changedTypes);
unblock(changedPacks);
return true;
}
void ConstraintSolver::block_(BlockedConstraintId target, NotNull<const Constraint> constraint)
{
blocked[target].push_back(constraint);
auto& count = blockedConstraints[constraint];
count += 1;
}
void ConstraintSolver::block(NotNull<const Constraint> target, NotNull<const Constraint> constraint)
{
if (logger)
logger->pushBlock(constraint, target);
if (FFlag::DebugLuauLogSolver)
printf("block Constraint %s on\t%s\n", toString(*target, opts).c_str(), toString(*constraint, opts).c_str());
block_(target.get(), constraint);
}
bool ConstraintSolver::block(TypeId target, NotNull<const Constraint> constraint)
{
if (logger)
logger->pushBlock(constraint, target);
if (FFlag::DebugLuauLogSolver)
printf("block TypeId %s on\t%s\n", toString(target, opts).c_str(), toString(*constraint, opts).c_str());
block_(follow(target), constraint);
return false;
}
bool ConstraintSolver::block(TypePackId target, NotNull<const Constraint> constraint)
{
if (logger)
logger->pushBlock(constraint, target);
if (FFlag::DebugLuauLogSolver)
printf("block TypeId %s on\t%s\n", toString(target, opts).c_str(), toString(*constraint, opts).c_str());
block_(target, constraint);
return false;
}
void ConstraintSolver::inheritBlocks(NotNull<const Constraint> source, NotNull<const Constraint> addition)
{
// Anything that is blocked on this constraint must also be blocked on our
// synthesized constraints.
auto blockedIt = blocked.find(source.get());
if (blockedIt != blocked.end())
{
for (const auto& blockedConstraint : blockedIt->second)
{
block(addition, blockedConstraint);
}
}
}
struct Blocker : TypeOnceVisitor
{
NotNull<ConstraintSolver> solver;
NotNull<const Constraint> constraint;
bool blocked = false;
explicit Blocker(NotNull<ConstraintSolver> solver, NotNull<const Constraint> constraint)
: solver(solver)
, constraint(constraint)
{
}
bool visit(TypeId ty, const PendingExpansionType&) override
{
blocked = true;
solver->block(ty, constraint);
return false;
}
bool visit(TypeId ty, const ClassType&) override
{
return false;
}
};
bool ConstraintSolver::blockOnPendingTypes(TypeId target, NotNull<const Constraint> constraint)
{
Blocker blocker{NotNull{this}, constraint};
blocker.traverse(target);
return !blocker.blocked;
}
bool ConstraintSolver::blockOnPendingTypes(TypePackId pack, NotNull<const Constraint> constraint)
{
Blocker blocker{NotNull{this}, constraint};
blocker.traverse(pack);
return !blocker.blocked;
}
void ConstraintSolver::unblock_(BlockedConstraintId progressed)
{
auto it = blocked.find(progressed);
if (it == blocked.end())
return;
// unblocked should contain a value always, because of the above check
for (NotNull<const Constraint> unblockedConstraint : it->second)
{
auto& count = blockedConstraints[unblockedConstraint];
if (FFlag::DebugLuauLogSolver)
printf("Unblocking count=%d\t%s\n", int(count), toString(*unblockedConstraint, opts).c_str());
// This assertion being hit indicates that `blocked` and
// `blockedConstraints` desynchronized at some point. This is problematic
// because we rely on this count being correct to skip over blocked
// constraints.
LUAU_ASSERT(count > 0);
count -= 1;
}
blocked.erase(it);
}
void ConstraintSolver::unblock(NotNull<const Constraint> progressed)
{
if (logger)
logger->popBlock(progressed);
return unblock_(progressed.get());
}
void ConstraintSolver::unblock(TypeId ty)
{
DenseHashSet<TypeId> seen{nullptr};
TypeId progressed = ty;
while (true)
{
if (seen.find(progressed))
iceReporter.ice("ConstraintSolver::unblock encountered a self-bound type!");
seen.insert(progressed);
if (logger)
logger->popBlock(progressed);
unblock_(progressed);
if (auto bt = get<BoundType>(progressed))
progressed = bt->boundTo;
else
break;
}
}
void ConstraintSolver::unblock(TypePackId progressed)
{
if (logger)
logger->popBlock(progressed);
return unblock_(progressed);
}
void ConstraintSolver::unblock(const std::vector<TypeId>& types)
{
for (TypeId t : types)
unblock(t);
}
void ConstraintSolver::unblock(const std::vector<TypePackId>& packs)
{
for (TypePackId t : packs)
unblock(t);
}
bool ConstraintSolver::isBlocked(TypeId ty)
{
return nullptr != get<BlockedType>(follow(ty)) || nullptr != get<PendingExpansionType>(follow(ty));
}
bool ConstraintSolver::isBlocked(TypePackId tp)
{
return nullptr != get<BlockedTypePack>(follow(tp));
}
bool ConstraintSolver::isBlocked(NotNull<const Constraint> constraint)
{
auto blockedIt = blockedConstraints.find(constraint);
return blockedIt != blockedConstraints.end() && blockedIt->second > 0;
}
ErrorVec ConstraintSolver::unify(TypeId subType, TypeId superType, NotNull<Scope> scope)
{
Unifier u{normalizer, scope, Location{}, Covariant};
u.enableScopeTests();
u.tryUnify(subType, superType);
if (!u.errors.empty())
{
TypeId errorType = errorRecoveryType();
u.tryUnify(subType, errorType);
u.tryUnify(superType, errorType);
}
const auto [changedTypes, changedPacks] = u.log.getChanges();
u.log.commit();
unblock(changedTypes);
unblock(changedPacks);
return std::move(u.errors);
}
ErrorVec ConstraintSolver::unify(TypePackId subPack, TypePackId superPack, NotNull<Scope> scope)
{
UnifierSharedState sharedState{&iceReporter};
Unifier u{normalizer, scope, Location{}, Covariant};
u.enableScopeTests();
u.tryUnify(subPack, superPack);
const auto [changedTypes, changedPacks] = u.log.getChanges();
u.log.commit();
unblock(changedTypes);
unblock(changedPacks);
return std::move(u.errors);
}
NotNull<Constraint> ConstraintSolver::pushConstraint(NotNull<Scope> scope, const Location& location, ConstraintV cv)
{
std::unique_ptr<Constraint> c = std::make_unique<Constraint>(scope, location, std::move(cv));
NotNull<Constraint> borrow = NotNull(c.get());
solverConstraints.push_back(std::move(c));
unsolvedConstraints.push_back(borrow);
return borrow;
}
TypeId ConstraintSolver::resolveModule(const ModuleInfo& info, const Location& location)
{
if (info.name.empty())
{
reportError(UnknownRequire{}, location);
return errorRecoveryType();
}
for (const auto& [location, path] : requireCycles)
{
if (!path.empty() && path.front() == info.name)
return builtinTypes->anyType;
}
ModulePtr module = moduleResolver->getModule(info.name);
if (!module)
{
if (!moduleResolver->moduleExists(info.name) && !info.optional)
reportError(UnknownRequire{moduleResolver->getHumanReadableModuleName(info.name)}, location);
return errorRecoveryType();
}
if (module->type != SourceCode::Type::Module)
{
reportError(IllegalRequire{module->humanReadableName, "Module is not a ModuleScript. It cannot be required."}, location);
return errorRecoveryType();
}
TypePackId modulePack = module->returnType;
if (get<Unifiable::Error>(modulePack))
return errorRecoveryType();
std::optional<TypeId> moduleType = first(modulePack);
if (!moduleType)
{
reportError(IllegalRequire{module->humanReadableName, "Module does not return exactly 1 value. It cannot be required."}, location);
return errorRecoveryType();
}
return *moduleType;
}
void ConstraintSolver::reportError(TypeErrorData&& data, const Location& location)
{
errors.emplace_back(location, std::move(data));
errors.back().moduleName = currentModuleName;
}
void ConstraintSolver::reportError(TypeError e)
{
errors.emplace_back(std::move(e));
errors.back().moduleName = currentModuleName;
}
TypeId ConstraintSolver::errorRecoveryType() const
{
return builtinTypes->errorRecoveryType();
}
TypePackId ConstraintSolver::errorRecoveryTypePack() const
{
return builtinTypes->errorRecoveryTypePack();
}
TypeId ConstraintSolver::unionOfTypes(TypeId a, TypeId b, NotNull<Scope> scope, bool unifyFreeTypes)
{
a = follow(a);
b = follow(b);
if (unifyFreeTypes && (get<FreeType>(a) || get<FreeType>(b)))
{
Unifier u{normalizer, scope, Location{}, Covariant};
u.enableScopeTests();
u.tryUnify(b, a);
if (u.errors.empty())
{
u.log.commit();
return a;
}
else
{
return builtinTypes->errorRecoveryType(builtinTypes->anyType);
}
}
if (*a == *b)
return a;
std::vector<TypeId> types = reduceUnion({a, b});
if (types.empty())
return builtinTypes->neverType;
if (types.size() == 1)
return types[0];
return arena->addType(UnionType{types});
}
TypePackId ConstraintSolver::anyifyModuleReturnTypePackGenerics(TypePackId tp)
{
tp = follow(tp);
if (const VariadicTypePack* vtp = get<VariadicTypePack>(tp))
{
TypeId ty = follow(vtp->ty);
return get<GenericType>(ty) ? builtinTypes->anyTypePack : tp;
}
if (!get<TypePack>(follow(tp)))
return tp;
std::vector<TypeId> resultTypes;
std::optional<TypePackId> resultTail;
TypePackIterator it = begin(tp);
for (TypePackIterator e = end(tp); it != e; ++it)
{
TypeId ty = follow(*it);
resultTypes.push_back(get<GenericType>(ty) ? builtinTypes->anyType : ty);
}
if (std::optional<TypePackId> tail = it.tail())
resultTail = anyifyModuleReturnTypePackGenerics(*tail);
return arena->addTypePack(resultTypes, resultTail);
}
} // namespace Luau