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SE-0157: Enable recursive protocol constraints by default.

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We don't know if they work in general, but specific cases of recursive
protocol constraints are working, and enabling them doesn't break
anything.
This commit is contained in:
Doug Gregor
2017-07-13 13:01:11 -07:00
parent e7077b10de
commit 469e9e08a5
9 changed files with 11 additions and 76 deletions
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46
lib/AST/GenericSignatureBuilder.cpp
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@@ -1945,9 +1945,7 @@ PotentialArchetype *PotentialArchetype::updateNestedTypeForConformance(
// If we were asked for a complete, well-formed archetype, make sure we
// process delayed requirements if anything changed.
SWIFT_DEFER {
ASTContext &ctx = assocType ? assocType->getASTContext()
: concreteDecl->getASTContext();
if (ctx.LangOpts.EnableRecursiveConstraints)
if (kind == ArchetypeResolutionKind::CompleteWellFormed)
getBuilder()->processDelayedRequirements();
};
@@ -3474,28 +3472,6 @@ ConstraintResult GenericSignatureBuilder::addSameTypeRequirementDirect(
}
}
// Local function to mark the given associated type as recursive,
// diagnosing it if this is the first such occurrence.
void GenericSignatureBuilder::markPotentialArchetypeRecursive(
PotentialArchetype *pa, ProtocolDecl *proto, const RequirementSource *source) {
if (pa->isRecursive())
return;
pa->setIsRecursive();
pa->addConformance(proto, source, *this);
if (!pa->getParent())
return;
auto assocType = pa->getResolvedAssociatedType();
if (!assocType || assocType->isInvalid())
return;
Diags.diagnose(assocType->getLoc(), diag::recursive_requirement_reference);
// Silence downstream errors referencing this associated type.
assocType->setInvalid();
}
ConstraintResult GenericSignatureBuilder::addInheritedRequirements(
TypeDecl *decl,
UnresolvedType type,
@@ -3546,26 +3522,6 @@ ConstraintResult GenericSignatureBuilder::addInheritedRequirements(
getFloatingSource(typeRepr, /*forInferred=*/true));
}
if (!decl->getASTContext().LangOpts.EnableRecursiveConstraints) {
// Check for direct recursion.
if (auto assocType = dyn_cast<AssociatedTypeDecl>(decl)) {
auto proto = assocType->getProtocol();
if (auto inheritedProto = inheritedType->getAs<ProtocolType>()) {
if (inheritedProto->getDecl() == proto ||
inheritedProto->getDecl()->inheritsFrom(proto)) {
auto source = getFloatingSource(typeRepr, /*forInferred=*/false);
if (auto resolved = resolve(type, source)) {
if (auto pa = resolved->getPotentialArchetype()) {
markPotentialArchetypeRecursive(pa, proto,
source.getSource(pa));
return ConstraintResult::Conflicting;
}
}
}
}
}
}
return addTypeRequirement(type, inheritedType,
getFloatingSource(typeRepr,
/*forInferred=*/false),