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[Generics] Canonicalization in GenericSignatureBuilder and SubstitutionMap #16806

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Merged
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May 23, 2018
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[Generics] Canonicalization in GenericSignatureBuilder and SubstitutionMap #16806

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5ed639f
[GSB] Canonicalize types when checking concrete and superclass constr…
DougGregor May 23, 2018
b0cc3ff
[SubstitutionMap] Canonicalize non-substitutable replacement types.
DougGregor May 23, 2018
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47 changes: 25 additions & 22 deletions lib/AST/GenericSignatureBuilder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6988,17 +6988,24 @@ void GenericSignatureBuilder::checkSameTypeConstraints(
void GenericSignatureBuilder::checkConcreteTypeConstraints(
TypeArrayView<GenericTypeParamType> genericParams,
EquivalenceClass *equivClass) {
// Resolve any thus-far-unresolved dependent types.
Type resolvedConcreteType =
resolveDependentMemberTypes(*this, equivClass->concreteType);

checkConstraintList<Type>(
genericParams, equivClass->concreteTypeConstraints,
[&](const ConcreteConstraint &constraint) {
return constraint.value->isEqual(equivClass->concreteType);
if (constraint.value->isEqual(resolvedConcreteType))
return true;

auto resolvedType =
resolveDependentMemberTypes(*this, constraint.value);
return resolvedType->isEqual(resolvedConcreteType);
},
[&](const Constraint<Type> &constraint) {
Type concreteType = constraint.value;

// If the concrete type is equivalent, the constraint is redundant.
// FIXME: Should check this constraint after substituting in the
// archetype anchors for each dependent type.
if (concreteType->isEqual(equivClass->concreteType))
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Why isn't this comparing to the resolved one?

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EEEP! Nice catch; I'll fix.

return ConstraintRelation::Redundant;

Expand All @@ -7013,33 +7020,28 @@ void GenericSignatureBuilder::checkConcreteTypeConstraints(
diag::redundant_same_type_to_concrete,
diag::same_type_redundancy_here);

// Resolve any thus-far-unresolved dependent types.
equivClass->concreteType =
resolveDependentMemberTypes(*this, equivClass->concreteType);
equivClass->concreteType = resolvedConcreteType;
}

void GenericSignatureBuilder::checkSuperclassConstraints(
TypeArrayView<GenericTypeParamType> genericParams,
EquivalenceClass *equivClass) {
assert(equivClass->superclass && "No superclass constraint?");

// FIXME: We should be substituting in the canonical type in context so
// we can resolve superclass requirements, e.g., if you had:
//
// class Foo<T>
// class Bar: Foo<Int>
//
// func foo<T, U where U: Bar, U: Foo<T>>(...) { ... }
//
// then the second `U: Foo<T>` constraint introduces a `T == Int`
// constraint, and we will need to perform that substitution for this final
// check.
// Resolve any this-far-unresolved dependent types.
Type resolvedSuperclass =
resolveDependentMemberTypes(*this, equivClass->superclass);

auto representativeConstraint =
checkConstraintList<Type>(
genericParams, equivClass->superclassConstraints,
[&](const ConcreteConstraint &constraint) {
return constraint.value->isEqual(equivClass->superclass);
if (constraint.value->isEqual(resolvedSuperclass))
return true;

Type resolvedType =
resolveDependentMemberTypes(*this, constraint.value);
return resolvedType->isEqual(equivClass->superclass);
},
[&](const Constraint<Type> &constraint) {
Type superclass = constraint.value;
Expand All @@ -7056,15 +7058,16 @@ void GenericSignatureBuilder::checkSuperclassConstraints(
diag::superclass_redundancy_here);

// Resolve any this-far-unresolved dependent types.
equivClass->superclass =
resolveDependentMemberTypes(*this, equivClass->superclass);
equivClass->superclass = resolvedSuperclass;

// If we have a concrete type, check it.
// FIXME: Substitute into the concrete type.
if (equivClass->concreteType) {
Type resolvedConcreteType =
resolveDependentMemberTypes(*this, equivClass->concreteType);
auto existing = equivClass->findAnyConcreteConstraintAsWritten();
// Make sure the concrete type fulfills the superclass requirement.
if (!equivClass->superclass->isExactSuperclassOf(equivClass->concreteType)){
if (!equivClass->superclass->isExactSuperclassOf(resolvedConcreteType)){
Impl->HadAnyError = true;
if (existing) {
Diags.diagnose(existing->source->getLoc(), diag::type_does_not_inherit,
Expand All @@ -7084,7 +7087,7 @@ void GenericSignatureBuilder::checkSuperclassConstraints(
diag::type_does_not_inherit,
representativeConstraint.getSubjectDependentType(
genericParams),
equivClass->concreteType, equivClass->superclass);
resolvedConcreteType, equivClass->superclass);
}
} else if (representativeConstraint.source->shouldDiagnoseRedundancy(true)
&& existing &&
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10 changes: 10 additions & 0 deletions lib/AST/SubstitutionMap.cpp
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Expand Up @@ -275,6 +275,11 @@ Type SubstitutionMap::lookupSubstitution(CanSubstitutableType type) const {

// Substitute into the replacement type.
replacementType = concreteType.subst(*this);

// If the generic signature is canonical, canonicalize the replacement type.
if (getGenericSignature()->isCanonical())
replacementType = replacementType->getCanonicalType();

return replacementType;
}

Expand All @@ -290,6 +295,11 @@ Type SubstitutionMap::lookupSubstitution(CanSubstitutableType type) const {
replacementType = ErrorType::get(type);

replacementType = lookupSubstitution(cast<SubstitutableType>(canonicalType));

// If the generic signature is canonical, canonicalize the replacement type.
if (getGenericSignature()->isCanonical())
replacementType = replacementType->getCanonicalType();

return replacementType;
}

Expand Down
16 changes: 16 additions & 0 deletions test/Generics/same_type_constraints.swift
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Expand Up @@ -378,3 +378,19 @@ typealias NotAnInt = Double
extension X11 where NotAnInt == Int { }
// expected-warning@-1{{neither type in same-type constraint ('NotAnInt' (aka 'Double') or 'Int') refers to a generic parameter or associated type}}
// expected-error@-2{{generic signature requires types 'NotAnInt' (aka 'Double') and 'Int' to be the same}}


struct X12<T> { }

protocol P12 {
associatedtype A
associatedtype B
}

func testP12a<T: P12>(_: T) where T.A == X12<Int>, T.A == X12<T.B>, T.B == Int { }
// expected-warning@-1{{redundant same-type constraint 'T.B' == 'Int'}}
// expected-note@-2{{same-type constraint 'T.B' == 'Int' written here}}

func testP12b<T: P12>(_: T) where T.B == Int, T.A == X12<T.B>, X12<T.B> == T.A { }
// expected-warning@-1{{redundant same-type constraint 'T.A' == 'X12<Int>'}}
// expected-note@-2{{same-type constraint 'T.A' == 'X12<Int>' written here}}