Merge pull request #36977 from bnbarham/cherry-pick-75379780

[5.5][Serialization] Add some checks for invalid types

Author: bnbarham

lib/Serialization/Serialization.cpp

@@ -2236,6 +2236,8 @@ static bool contextDependsOn(const NominalTypeDecl *decl,
 static void collectDependenciesFromType(llvm::SmallSetVector<Type, 4> &seen,
                                         Type ty,
                                         const DeclContext *excluding) {
+  if (!ty)
+    return;
   ty.visit([&](Type next) {
     auto *nominal = next->getAnyNominal();
     if (!nominal)
@@ -3064,6 +3066,9 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
 
     SmallVector<TypeID, 8> inheritedAndDependencyTypes;
     for (auto inherited : extension->getInherited()) {
+      if (extension->getASTContext().LangOpts.AllowModuleWithCompilerErrors &&
+          !inherited.getType())
+        continue;
       assert(!inherited.getType()->hasArchetype());
       inheritedAndDependencyTypes.push_back(S.addTypeRef(inherited.getType()));
     }

test/Frontend/allow-errors.swift

@@ -55,6 +55,11 @@ public func invalidFuncBody() -> ValidStructInvalidMember {
 }
 
 public func invalidFunc() -> undefined {} // expected-error {{cannot find type 'undefined'}}
+
+extension undefined: undefined {} // expected-error {{cannot find type 'undefined'}}
+
+class GenericClass<T> {}
+class InvalidSuperclass: GenericClass<undefined> {} // expected-error {{cannot find type 'undefined'}}
 #endif
 
 // RUN: %target-swift-frontend -emit-module -o %t/validUses.swiftmodule -experimental-allow-module-with-compiler-errors -I%t -D VALID_USES %s 2>&1 | %FileCheck -check-prefix=CHECK-VALID %s