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[ConstraintSystem] Record originator constraint for each type variable binding #28752

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Merged
merged 7 commits into from
Dec 13, 2019
Merged

[ConstraintSystem] Record originator constraint for each type variable binding #28752

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bb51a8f
[ConstraintSystem] Use originating constraint as a source for a binding
xedin Dec 12, 2019
413dbbc
[TypeChecker] Don't try to join to function type with different escap…
xedin Dec 12, 2019
f259286
[CSFix] Convert missing explicit @escaping fix to be a contextual mis…
xedin Dec 12, 2019
cc50b46
[Diagnostics] Preserve raw from/to types in contextual mismatch diagn…
xedin Dec 12, 2019
382013f
[Diagnostics] Convert missing @escaping diagnostic to contextual failure
xedin Dec 12, 2019
87beea3
[ConstraintSystem] Use binding as a source of type variable assignment
xedin Dec 12, 2019
c4b74a3
[ConstraintSystem] Remove `getSourceKind()` from `PotentialBinding`
xedin Dec 13, 2019
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2 changes: 1 addition & 1 deletion lib/AST/TypeJoinMeet.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -314,7 +314,7 @@ CanType TypeJoin::visitFunctionType(CanType second) {
auto secondExtInfo = secondFnTy->getExtInfo();

// FIXME: Properly handle these attributes.
if (firstExtInfo.withNoEscape(false) != secondExtInfo.withNoEscape(false))
if (firstExtInfo != secondExtInfo)
return Unimplemented;

if (!AnyFunctionType::equalParams(firstFnTy->getParams(),
Expand Down
91 changes: 43 additions & 48 deletions lib/Sema/CSBindings.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -81,7 +81,7 @@ ConstraintSystem::determineBestBindings() {
continue;

bindings.addPotentialBinding(
{type, AllowedBindingKind::Supertypes, binding.BindingSource});
binding.withSameSource(type, AllowedBindingKind::Supertypes));
}
}

Expand Down Expand Up @@ -143,8 +143,8 @@ void ConstraintSystem::PotentialBindings::addPotentialBinding(
!binding.BindingType->hasUnresolvedType() &&
!binding.BindingType->hasTypeVariable() &&
!binding.BindingType->hasUnboundGenericType() &&
!binding.DefaultedProtocol && !binding.isDefaultableBinding() &&
allowJoinMeet) {
!binding.hasDefaultedLiteralProtocol() &&
!binding.isDefaultableBinding() && allowJoinMeet) {
if (lastSupertypeIndex) {
auto &lastBinding = Bindings[*lastSupertypeIndex];
auto lastType = lastBinding.BindingType->getWithoutSpecifierType();
Expand All @@ -164,7 +164,7 @@ void ConstraintSystem::PotentialBindings::addPotentialBinding(
lastSupertypeIndex = Bindings.size();
}

if (auto *literalProtocol = binding.DefaultedProtocol)
if (auto *literalProtocol = binding.getDefaultedLiteralProtocol())
foundLiteralBinding(literalProtocol);

// If the type variable can't bind to an lvalue, make sure the
Expand Down Expand Up @@ -371,7 +371,7 @@ ConstraintSystem::getPotentialBindingForRelationalConstraint(
kind = AllowedBindingKind::Exact;
}

return PotentialBinding{type, kind, constraint->getKind()};
return PotentialBinding{type, kind, constraint};
}

/// Retrieve the set of potential type bindings for the given
Expand Down Expand Up @@ -466,9 +466,8 @@ ConstraintSystem::getPotentialBindings(TypeVariableType *typeVar) const {
path.back().getKind() == ConstraintLocator::ClosureResult &&
binding->Kind == AllowedBindingKind::Supertypes &&
exactTypes.insert(voidType).second) {
result.addPotentialBinding(
{voidType, binding->Kind, constraint->getKind()},
/*allowJoinMeet=*/false);
result.addPotentialBinding({voidType, binding->Kind, constraint},
/*allowJoinMeet=*/false);
}
}
}
Expand Down Expand Up @@ -551,9 +550,8 @@ ConstraintSystem::getPotentialBindings(TypeVariableType *typeVar) const {
if (!exactTypes.insert(defaultType->getCanonicalType()).second)
continue;

literalBindings.push_back({defaultType, AllowedBindingKind::Subtypes,
constraint->getKind(),
constraint->getProtocol()});
literalBindings.push_back(
{defaultType, AllowedBindingKind::Subtypes, constraint});
continue;
}

Expand All @@ -578,9 +576,8 @@ ConstraintSystem::getPotentialBindings(TypeVariableType *typeVar) const {

if (!matched) {
exactTypes.insert(defaultType->getCanonicalType());
literalBindings.push_back({defaultType, AllowedBindingKind::Subtypes,
constraint->getKind(),
constraint->getProtocol()});
literalBindings.push_back(
{defaultType, AllowedBindingKind::Subtypes, constraint});
}

break;
Expand Down Expand Up @@ -677,7 +674,7 @@ ConstraintSystem::getPotentialBindings(TypeVariableType *typeVar) const {
// might be covered by non-defaulted bindings.
bool updatedBindingType = false;
for (auto &literalBinding : literalBindings) {
auto *protocol = literalBinding.DefaultedProtocol;
auto *protocol = literalBinding.getDefaultedLiteralProtocol();

assert(protocol);

Expand Down Expand Up @@ -716,7 +713,7 @@ ConstraintSystem::getPotentialBindings(TypeVariableType *typeVar) const {
}

for (auto &literalBinding : literalBindings) {
auto *protocol = literalBinding.DefaultedProtocol;
auto *protocol = literalBinding.getDefaultedLiteralProtocol();
// For any literal type that has been covered, skip them.
if (coveredLiteralProtocols.count(protocol) == 0)
result.addPotentialBinding(std::move(literalBinding));
Expand All @@ -729,9 +726,7 @@ ConstraintSystem::getPotentialBindings(TypeVariableType *typeVar) const {
if (!exactTypes.insert(type->getCanonicalType()).second)
continue;

result.addPotentialBinding({type, AllowedBindingKind::Exact,
constraint->getKind(), nullptr,
constraint->getLocator()});
result.addPotentialBinding({type, AllowedBindingKind::Exact, constraint});
}

// If there are no bindings, typeVar may be a hole.
Expand All @@ -745,9 +740,8 @@ ConstraintSystem::getPotentialBindings(TypeVariableType *typeVar) const {
if (locator->isLastElement<LocatorPathElt::MemberRefBase>())
result.PotentiallyIncomplete = true;

result.addPotentialBinding({getASTContext().TheUnresolvedType,
AllowedBindingKind::Exact, ConstraintKind::Defaultable, nullptr,
typeVar->getImpl().getLocator()});
result.addPotentialBinding(
PotentialBinding::forHole(getASTContext(), locator));
}

// Determine if the bindings only constrain the type variable from above with
Expand Down Expand Up @@ -918,11 +912,11 @@ bool TypeVarBindingProducer::computeNext() {

// If we have a protocol with a default type, look for alternative
// types to the default.
if (NumTries == 0 && binding.DefaultedProtocol) {
auto knownKind = *(binding.DefaultedProtocol->getKnownProtocolKind());
if (NumTries == 0 && binding.hasDefaultedLiteralProtocol()) {
auto knownKind =
*(binding.getDefaultedLiteralProtocol()->getKnownProtocolKind());
for (auto altType : CS.getAlternativeLiteralTypes(knownKind)) {
addNewBinding({altType, BindingKind::Subtypes, binding.BindingSource,
binding.DefaultedProtocol});
addNewBinding(binding.withSameSource(altType, BindingKind::Subtypes));
}
}

Expand All @@ -939,10 +933,10 @@ bool TypeVarBindingProducer::computeNext() {
if (auto otherTypeVar = objTy->getAs<TypeVariableType>()) {
if (TypeVar->getImpl().canBindToLValue() ==
otherTypeVar->getImpl().canBindToLValue()) {
addNewBinding({objTy, binding.Kind, binding.BindingSource});
addNewBinding(binding.withSameSource(objTy, binding.Kind));
}
} else {
addNewBinding({objTy, binding.Kind, binding.BindingSource});
addNewBinding(binding.withSameSource(objTy, binding.Kind));
}
}
}
Expand All @@ -953,7 +947,7 @@ bool TypeVarBindingProducer::computeNext() {
for (auto supertype : enumerateDirectSupertypes(type)) {
// If we're not allowed to try this binding, skip it.
if (auto simplifiedSuper = CS.checkTypeOfBinding(TypeVar, supertype))
addNewBinding({*simplifiedSuper, binding.Kind, binding.BindingSource});
addNewBinding(binding.withType(*simplifiedSuper));
}
}

Expand All @@ -968,12 +962,13 @@ bool TypeVarBindingProducer::computeNext() {

bool TypeVariableBinding::attempt(ConstraintSystem &cs) const {
auto type = Binding.BindingType;
auto *locator = TypeVar->getImpl().getLocator();
auto *srcLocator = Binding.getLocator();
auto *dstLocator = TypeVar->getImpl().getLocator();

if (Binding.DefaultedProtocol) {
type = cs.openUnboundGenericType(type, locator);
if (Binding.hasDefaultedLiteralProtocol()) {
type = cs.openUnboundGenericType(type, dstLocator);
type = type->reconstituteSugar(/*recursive=*/false);
} else if (Binding.BindingSource == ConstraintKind::ArgumentConversion &&
} else if (srcLocator->isLastElement<LocatorPathElt::ApplyArgToParam>() &&
!type->hasTypeVariable() && cs.isCollectionType(type)) {
// If the type binding comes from the argument conversion, let's
// instead of binding collection types directly, try to bind
Expand All @@ -984,27 +979,27 @@ bool TypeVariableBinding::attempt(ConstraintSystem &cs) const {
auto UGT = UnboundGenericType::get(BGT->getDecl(), BGT->getParent(),
BGT->getASTContext());

type = cs.openUnboundGenericType(UGT, locator);
type = cs.openUnboundGenericType(UGT, dstLocator);
type = type->reconstituteSugar(/*recursive=*/false);
}

// FIXME: We want the locator that indicates where the binding came
// from.
cs.addConstraint(ConstraintKind::Bind, TypeVar, type, locator);
cs.addConstraint(ConstraintKind::Bind, TypeVar, type, srcLocator);

// If this was from a defaultable binding note that.
if (Binding.isDefaultableBinding()) {
cs.DefaultedConstraints.push_back(Binding.DefaultableBinding);

if (locator->isForGenericParameter() && type->isHole()) {
// Drop `generic parameter` locator element so that all missing
// generic parameters related to the same path can be coalesced later.
auto path = locator->getPath();
auto genericParam = locator->getGenericParameter();
auto *fix = DefaultGenericArgument::create(cs, genericParam,
cs.getConstraintLocator(locator->getAnchor(), path.drop_back()));
if (cs.recordFix(fix))
return true;
cs.DefaultedConstraints.push_back(srcLocator);

if (type->isHole()) {
if (auto *GP = TypeVar->getImpl().getGenericParameter()) {
auto path = dstLocator->getPath();
// Drop `generic parameter` locator element so that all missing
// generic parameters related to the same path can be coalesced later.
auto *fix = DefaultGenericArgument::create(
cs, GP,
cs.getConstraintLocator(dstLocator->getAnchor(), path.drop_back()));
if (cs.recordFix(fix))
return true;
}
}
}

Expand Down
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