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More associated conformance cleanups #69200

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Merged
merged 3 commits into from
Oct 16, 2023
Merged

More associated conformance cleanups #69200

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b891b56
Sema: Use forEachAssociatedConformance() from ensureRequirementsAreSa…
slavapestov Oct 11, 2023
82cbcf1
Sema: Remove some code from checkTypeWitness() that no longer appears…
slavapestov Oct 12, 2023
273baf5
Sema: Remove bespoke recursivelySubstituteBaseType() in favor of plai…
slavapestov Oct 12, 2023
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69 changes: 10 additions & 59 deletions lib/Sema/TypeCheckProtocol.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4763,21 +4763,6 @@ swift::checkTypeWitness(Type type, AssociatedTypeDecl *assocType,
KnownProtocolKind::Sendable))
.isInvalid())
return CheckTypeWitnessResult::forConformance(reqProto);

// FIXME: Why is conformsToProtocol() not enough? The stdlib doesn't
// build unless we fail here while inferring an associated type
// somewhere.
if (contextType->isSpecialized()) {
auto *decl = contextType->getAnyNominal();
auto subMap = contextType->getContextSubstitutionMap(
module,
decl,
decl->getGenericEnvironmentOfContext());
for (auto replacement : subMap.getReplacementTypes()) {
if (replacement->hasError())
return CheckTypeWitnessResult::forConformance(reqProto);
}
}
}

if (sig->requiresClass(depTy) &&
Expand Down Expand Up @@ -5196,10 +5181,8 @@ void ConformanceChecker::ensureRequirementsAreSatisfied() {
return false;
});

for (auto req : proto->getRequirementSignature().getRequirements()) {
if (req.getKind() == RequirementKind::Conformance) {
auto depTy = req.getFirstType();
auto *proto = req.getProtocolDecl();
Conformance->forEachAssociatedConformance(
[&](Type depTy, ProtocolDecl *proto, unsigned index) {
auto conformance = Conformance->getAssociatedConformance(depTy, proto);
if (conformance.isConcrete()) {
auto *concrete = conformance.getConcrete();
Expand All @@ -5208,8 +5191,9 @@ void ConformanceChecker::ensureRequirementsAreSatisfied() {
conformance, where,
depTy, replacementTy);
}
}
}

return false;
});
}

#pragma mark Protocol conformance checking
Expand Down Expand Up @@ -7070,51 +7054,18 @@ ValueWitnessRequest::evaluate(Evaluator &eval,
return known->second;
}

/// A stripped-down version of Type::subst that only works on the protocol
/// Self type wrapped in zero or more DependentMemberTypes.
static Type
recursivelySubstituteBaseType(ModuleDecl *module,
NormalProtocolConformance *conformance,
DependentMemberType *depMemTy) {
Type origBase = depMemTy->getBase();

// Recursive case.
if (auto *depBase = origBase->getAs<DependentMemberType>()) {
Type substBase = recursivelySubstituteBaseType(
module, conformance, depBase);
return depMemTy->substBaseType(module, substBase);
}

// Base case. The associated type's protocol should be either the
// conformance protocol or an inherited protocol.
auto *reqProto = depMemTy->getAssocType()->getProtocol();
assert(origBase->isEqual(reqProto->getSelfInterfaceType()));

ProtocolConformance *reqConformance = conformance;

// If we have an inherited protocol just look up the conformance.
if (reqProto != conformance->getProtocol()) {
reqConformance = module->lookupConformance(conformance->getType(), reqProto)
.getConcrete();
}

return reqConformance->getTypeWitness(depMemTy->getAssocType());
}

ProtocolConformanceRef
AssociatedConformanceRequest::evaluate(Evaluator &eval,
NormalProtocolConformance *conformance,
CanType origTy, ProtocolDecl *reqProto,
unsigned index) const {
auto *module = conformance->getDeclContext()->getParentModule();
Type substTy;

if (origTy->isEqual(conformance->getProtocol()->getSelfInterfaceType())) {
substTy = conformance->getType();
} else {
auto *depMemTy = origTy->castTo<DependentMemberType>();
substTy = recursivelySubstituteBaseType(module, conformance, depMemTy);
}
auto subMap = SubstitutionMap::getProtocolSubstitutions(
conformance->getProtocol(),
conformance->getType(),
ProtocolConformanceRef(conformance));
auto substTy = origTy.subst(subMap);

// Looking up a conformance for a contextual type and mapping the
// conformance context produces a more accurate result than looking
Expand Down