LookupTypeResult TypeChecker::lookupMemberType(DeclContext *dc,
Type type, Identifier name,
NameLookupOptions options) {
LookupTypeResult result;
// Look through an inout type.
if (auto inout = type->getAs<InOutType>())
type = inout->getObjectType();
// Look through the metatype.
if (auto metaT = type->getAs<AnyMetatypeType>())
type = metaT->getInstanceType();
// Callers must cope with dependent types directly.
assert(!type->isTypeParameter());
// Look for members with the given name.
SmallVector<ValueDecl *, 4> decls;
NLOptions subOptions = NL_QualifiedDefault | NL_OnlyTypes;
if (options.contains(NameLookupFlags::KnownPrivate))
subOptions |= NL_KnownNonCascadingDependency;
if (options.contains(NameLookupFlags::ProtocolMembers))
subOptions |= NL_ProtocolMembers;
if (options.contains(NameLookupFlags::IgnoreAccessibility))
subOptions |= NL_IgnoreAccessibility;
if (!dc->lookupQualified(type, name, subOptions, this, decls))
return result;
// Look through the declarations, keeping only the unique type declarations.
llvm::SmallPtrSet<CanType, 4> types;
SmallVector<AssociatedTypeDecl *, 4> inferredAssociatedTypes;
for (auto decl : decls) {
auto *typeDecl = cast<TypeDecl>(decl);
// FIXME: This should happen before we attempt shadowing checks.
validateDecl(typeDecl);
if (!typeDecl->hasType()) // FIXME: recursion-breaking hack
continue;
// If we're looking up a member of a protocol, we must take special care.
if (typeDecl->getDeclContext()->getAsProtocolOrProtocolExtensionContext()) {
// We don't allow lookups of an associated type or typealias of an
// existential type, because we have no way to represent such types.
//
// This is diagnosed further on down in resolveNestedIdentTypeComponent().
if (type->isExistentialType()) {
auto memberType = typeDecl->getInterfaceType()->getRValueInstanceType();
if (memberType->hasTypeParameter()) {
// If we haven't seen this type result yet, add it to the result set.
if (types.insert(memberType->getCanonicalType()).second)
result.Results.push_back({typeDecl, memberType});
continue;
}
}
// If we're looking up an associated type of a concrete type,
// record it later for conformance checking; we might find a more
// direct typealias with the same name later.
if (auto assocType = dyn_cast<AssociatedTypeDecl>(typeDecl)) {
if (!type->is<ArchetypeType>()) {
inferredAssociatedTypes.push_back(assocType);
continue;
}
}
// We are looking up an associated type of an archetype, or a
// protocol typealias or an archetype or concrete type.
//
// Proceed with the usual path below.
}
// Substitute the base into the member's type.
auto memberType = substMemberTypeWithBase(dc->getParentModule(),
typeDecl, type,
/*isTypeReference=*/true);
// FIXME: It is not clear why this substitution can fail, but the
// standard library won't build without this check.
if (!memberType)
continue;
// If we haven't seen this type result yet, add it to the result set.
if (types.insert(memberType->getCanonicalType()).second)
result.Results.push_back({typeDecl, memberType});
}
if (result.Results.empty()) {
// We couldn't find any normal declarations. Let's try inferring
// associated types.
ConformanceCheckOptions conformanceOptions;
if (options.contains(NameLookupFlags::KnownPrivate))
conformanceOptions |= ConformanceCheckFlags::InExpression;
for (AssociatedTypeDecl *assocType : inferredAssociatedTypes) {
// If the type does not actually conform to the protocol, skip this
// member entirely.
auto *protocol = cast<ProtocolDecl>(assocType->getDeclContext());
ProtocolConformance *conformance = nullptr;
if (!conformsToProtocol(type, protocol, dc, conformanceOptions,
&conformance) ||
!conformance) {
// FIXME: This is an error path. Should we try to recover?
continue;
}
// Use the type witness.
Type memberType =
conformance->getTypeWitness(assocType, this).getReplacement();
assert(memberType && "Missing type witness?");
// If we haven't seen this type result yet, add it to the result set.
if (types.insert(memberType->getCanonicalType()).second)
result.Results.push_back({assocType, memberType});
}
}
return result;
}
LookupTypeResult TypeChecker::lookupMemberType(DeclContext *dc,
Type type, Identifier name,
NameLookupOptions options) {
LookupTypeResult result;
// Look through an inout type.
if (auto inout = type->getAs<InOutType>())
type = inout->getObjectType();
// Look through the metatype.
if (auto metaT = type->getAs<AnyMetatypeType>())
type = metaT->getInstanceType();
// Callers must cope with dependent types directly.
assert(!type->isTypeParameter());
// Look for members with the given name.
SmallVector<ValueDecl *, 4> decls;
NLOptions subOptions = NL_QualifiedDefault;
if (options.contains(NameLookupFlags::KnownPrivate))
subOptions |= NL_KnownNonCascadingDependency;
if (options.contains(NameLookupFlags::ProtocolMembers))
subOptions |= NL_ProtocolMembers;
if (options.contains(NameLookupFlags::IgnoreAccessibility))
subOptions |= NL_IgnoreAccessibility;
if (!dc->lookupQualified(type, name, subOptions, this, decls))
return result;
// Look through the declarations, keeping only the unique type declarations.
llvm::SmallPtrSet<CanType, 4> types;
SmallVector<AssociatedTypeDecl *, 4> inferredAssociatedTypes;
for (auto decl : decls) {
// Ignore non-types found by name lookup.
auto typeDecl = dyn_cast<TypeDecl>(decl);
if (!typeDecl)
continue;
// FIXME: This should happen before we attempt shadowing checks.
validateDecl(typeDecl);
if (!typeDecl->hasType()) // FIXME: recursion-breaking hack
continue;
// If we found a member of a protocol type when looking into a non-protocol,
// non-archetype type, only include this member in the result set if
// this member was used as the default definition or otherwise inferred.
if (auto assocType = dyn_cast<AssociatedTypeDecl>(typeDecl)) {
if (!type->is<ArchetypeType>() && !type->isExistentialType()) {
inferredAssociatedTypes.push_back(assocType);
continue;
}
}
// Ignore typealiases found in protocol members.
if (auto alias = dyn_cast<TypeAliasDecl>(typeDecl)) {
auto aliasParent = alias->getParent();
if (aliasParent != dc && isa<ProtocolDecl>(aliasParent))
continue;
}
// Substitute the base into the member's type.
if (Type memberType = substMemberTypeWithBase(dc->getParentModule(),
typeDecl, type,
/*isTypeReference=*/true)) {
// If we haven't seen this type result yet, add it to the result set.
if (types.insert(memberType->getCanonicalType()).second)
result.Results.push_back({typeDecl, memberType});
}
}
if (result.Results.empty()) {
// We couldn't find any normal declarations. Let's try inferring
// associated types.
ConformanceCheckOptions conformanceOptions;
if (options.contains(NameLookupFlags::KnownPrivate))
conformanceOptions |= ConformanceCheckFlags::InExpression;
for (AssociatedTypeDecl *assocType : inferredAssociatedTypes) {
// If the type does not actually conform to the protocol, skip this
// member entirely.
auto *protocol = cast<ProtocolDecl>(assocType->getDeclContext());
ProtocolConformance *conformance = nullptr;
if (!conformsToProtocol(type, protocol, dc, conformanceOptions,
&conformance) ||
!conformance) {
// FIXME: This is an error path. Should we try to recover?
continue;
}
// Use the type witness.
Type memberType =
conformance->getTypeWitness(assocType, this).getReplacement();
assert(memberType && "Missing type witness?");
// If we haven't seen this type result yet, add it to the result set.
if (types.insert(memberType->getCanonicalType()).second)
result.Results.push_back({assocType, memberType});
}
}
return result;
}