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[Constraint solver] Check conditional requirements for type erasure.

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Rather than wantonly dropping the conditional requirements when checking
for type erasure, add them in the same way we do for (e.g.) conformance
checking for generics. Fixes rdar://problem/35480860.
This commit is contained in:
Doug Gregor
2017-11-19 22:22:32 -08:00
parent d58a596be1
commit a6913bb2ef
2 changed files with 31 additions and 14 deletions
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34
lib/Sema/CSSimplify.cpp
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@@ -2582,6 +2582,24 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
return SolutionKind::Unsolved;
}
/// Record the given conformance as the result, adding any conditional
/// requirements if necessary.
auto recordConformance = [&](ProtocolConformanceRef conformance) {
// Record the conformance.
CheckedConformances.push_back({getConstraintLocator(locator), conformance});
// This conformance may be conditional, in which case we need to consider
// those requirements as constraints too.
if (conformance.isConcrete()) {
for (const auto &req : conformance.getConditionalRequirements()) {
// FIXME: Use a more specific locator.
addConstraint(req, locator);
}
}
return SolutionKind::Solved;
};
// For purposes of argument type matching, existential types don't need to
// conform -- they only need to contain the protocol, so check that
// separately.
@@ -2590,9 +2608,7 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
if (auto conformance =
TC.containsProtocol(type, protocol, DC,
ConformanceCheckFlags::InExpression)) {
CheckedConformances.push_back({getConstraintLocator(locator),
*conformance});
return SolutionKind::Solved;
return recordConformance(*conformance);
}
break;
case ConstraintKind::ConformsTo:
@@ -2601,17 +2617,7 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
if (auto conformance =
TC.conformsToProtocol(type, protocol, DC,
ConformanceCheckFlags::InExpression)) {
CheckedConformances.push_back({getConstraintLocator(locator),
*conformance});
// This conformance may be conditional, in which case we need to consider
// those requirements as constraints too.
if (conformance->isConcrete()) {
for (auto req : conformance->getConditionalRequirements()) {
addConstraint(req, locator);
}
}
return SolutionKind::Solved;
return recordConformance(*conformance);
}
break;
}