Adopt GenericSignature::isValidTypeInContext for nested archetypes

Author: DougGregor

lib/AST/GenericSignature.cpp

@@ -467,16 +467,7 @@ CanType GenericSignatureImpl::getCanonicalTypeInContext(Type type) const {
 }
 
 bool GenericSignatureImpl::isValidTypeInContext(Type type) const {
-  auto &ctx = getASTContext();
-  switch (ctx.LangOpts.EnableRequirementMachine) {
-  case RequirementMachineMode::Disabled:
-    llvm::errs() << "Not implemented\n";
-    abort();
-
-  case RequirementMachineMode::Enabled:
-  case RequirementMachineMode::Verify:
-    return getRequirementMachine()->isValidTypeInContext(type);
-  }
+  return getRequirementMachine()->isValidTypeInContext(type);
 }
 
 ArrayRef<CanTypeWrapper<GenericTypeParamType>>

lib/AST/Type.cpp

@@ -3703,10 +3703,12 @@ Type ArchetypeType::getNestedType(AssociatedTypeDecl *assocType) {
 }
 
 Type ArchetypeType::getNestedTypeByName(Identifier name) {
-  auto memberDecl = getGenericEnvironment()->getGenericSignature()
-      ->lookupNestedType(getInterfaceType(), name);
-  if (auto assocType = dyn_cast_or_null<AssociatedTypeDecl>(memberDecl)) {
-    return getNestedType(assocType);
+  Type interfaceType = getInterfaceType();
+  Type memberInterfaceType = DependentMemberType::get(interfaceType, name);
+  auto genericSig = getGenericEnvironment()->getGenericSignature();
+  if (genericSig->isValidTypeInContext(memberInterfaceType)) {
+    return getGenericEnvironment()->getOrCreateArchetypeFromInterfaceType(
+        memberInterfaceType);
   }
 
   return Type();