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[CSBindings] Inference cannot fail #35529

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Merged
merged 1 commit into from
Jan 21, 2021
Merged

[CSBindings] Inference cannot fail #35529

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2 changes: 1 addition & 1 deletion include/swift/Sema/CSBindings.h
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Original file line number Diff line number Diff line change
Expand Up @@ -464,7 +464,7 @@ struct PotentialBindings {
Optional<PotentialBinding> inferFromRelational(Constraint *constraint);

public:
bool infer(Constraint *constraint);
void infer(Constraint *constraint);

/// Finalize binding computation for this type variable by
/// inferring bindings from context e.g. transitive bindings.
Expand Down
34 changes: 13 additions & 21 deletions lib/Sema/CSBindings.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -812,13 +812,8 @@ PotentialBindings ConstraintSystem::inferBindingsFor(TypeVariableType *typeVar,
auto constraints = CG.gatherConstraints(
typeVar, ConstraintGraph::GatheringKind::EquivalenceClass);

for (auto *constraint : constraints) {
bool failed = bindings.infer(constraint);

// Upon inference failure let's produce an empty set of bindings.
if (failed)
return {*this, typeVar};
}
for (auto *constraint : constraints)
bindings.infer(constraint);

if (finalize) {
llvm::SmallDenseMap<TypeVariableType *, PotentialBindings> inferred;
Expand Down Expand Up @@ -1068,7 +1063,7 @@ PotentialBindings::inferFromRelational(Constraint *constraint) {
/// Retrieve the set of potential type bindings for the given
/// representative type variable, along with flags indicating whether
/// those types should be opened.
bool PotentialBindings::infer(Constraint *constraint) {
void PotentialBindings::infer(Constraint *constraint) {
switch (constraint->getKind()) {
case ConstraintKind::Bind:
case ConstraintKind::Equal:
Expand Down Expand Up @@ -1152,8 +1147,10 @@ bool PotentialBindings::infer(Constraint *constraint) {
// [existential] metatype.
auto dynamicType = constraint->getFirstType();
if (auto *tv = dynamicType->getAs<TypeVariableType>()) {
if (tv->getImpl().getRepresentative(nullptr) == TypeVar)
return true;
if (tv->getImpl().getRepresentative(nullptr) == TypeVar) {
DelayedBy.push_back(constraint);
break;
}
}

// This is right-hand side, let's continue.
Expand All @@ -1174,19 +1171,14 @@ bool PotentialBindings::infer(Constraint *constraint) {
// associated with closure literal (e.g. coercion to some other
// type) let's delay resolving the closure until the disjunction
// is attempted.
if (TypeVar->getImpl().isClosureType())
return true;

DelayedBy.push_back(constraint);
break;

case ConstraintKind::ConformsTo:
case ConstraintKind::SelfObjectOfProtocol: {
auto protocolTy = constraint->getSecondType();
if (!protocolTy->is<ProtocolType>())
return false;

Protocols.push_back(constraint);
if (protocolTy->is<ProtocolType>())
Protocols.push_back(constraint);
break;
}

Expand Down Expand Up @@ -1247,15 +1239,15 @@ bool PotentialBindings::infer(Constraint *constraint) {
// side of a one-way binding.
auto firstType = constraint->getFirstType();
if (auto *tv = firstType->getAs<TypeVariableType>()) {
if (tv->getImpl().getRepresentative(nullptr) == TypeVar)
return true;
if (tv->getImpl().getRepresentative(nullptr) == TypeVar) {
DelayedBy.push_back(constraint);
break;
}
}

break;
}
}

return false;
}

LiteralBindingKind PotentialBindings::getLiteralKind() const {
Expand Down