[Metadata] Emit complete context descriptors for parents of anonymous contexts

When a (file)private entity occurs inside a generic context, we still need
information about the genericity of the enclosing context to demangle
to metadata. Emit complete context descriptors for parents of anonymous
contexts.

Fixes rdar://problem/46109026.

Author: DougGregor

lib/Demangling/OldRemangler.cpp

@@ -1221,6 +1221,20 @@ void Remangler::mangleEntityContext(Node *node, EntityContext &ctx) {
   // Remember that we're mangling a context.
   EntityContext::ManglingContextRAII raii(ctx);
 
+  // Deal with bound generic types.
+  switch (node->getKind()) {
+    case Node::Kind::BoundGenericStructure:
+    case Node::Kind::BoundGenericEnum:
+    case Node::Kind::BoundGenericClass:
+    case Node::Kind::BoundGenericOtherNominalType:
+    case Node::Kind::BoundGenericTypeAlias:
+      mangleAnyNominalType(node, ctx);
+      return;
+
+    default:
+      break;
+  }
+
   switch (node->getKind()) {
 #define NODE(ID)                                \
   case Node::Kind::ID:
@@ -1731,6 +1745,7 @@ void Remangler::mangleExtension(Node *node, EntityContext &ctx) {
   if (node->getNumChildren() == 3) {
     mangleDependentGenericSignature(node->begin()[2]); // generic sig
   }
+
   mangleEntityContext(node->begin()[1], ctx); // context
 }
 

lib/IRGen/GenDecl.cpp

@@ -740,7 +740,8 @@ void IRGenModule::emitRuntimeRegistration() {
 /// For any other kind of context, this returns an anonymous context descriptor
 /// for the context.
 ConstantReference
-IRGenModule::getAddrOfParentContextDescriptor(DeclContext *from) {
+IRGenModule::getAddrOfParentContextDescriptor(DeclContext *from,
+                                              bool fromAnonymousContext) {
   // Some types get special treatment.
   if (auto Type = dyn_cast<NominalTypeDecl>(from)) {
     // Use a special module context if we have one.
@@ -757,7 +758,7 @@ IRGenModule::getAddrOfParentContextDescriptor(DeclContext *from) {
 
     // Wrap up private types in an anonymous context for the containing file
     // unit so that the runtime knows they have unstable identity.
-    if (Type->isOutermostPrivateOrFilePrivateScope())
+    if (!fromAnonymousContext && Type->isOutermostPrivateOrFilePrivateScope())
       return {getAddrOfAnonymousContextDescriptor(Type),
               ConstantReference::Direct};
   }
@@ -771,15 +772,17 @@ IRGenModule::getAddrOfParentContextDescriptor(DeclContext *from) {
   case DeclContextKind::TopLevelCodeDecl:
   case DeclContextKind::Initializer:
   case DeclContextKind::SerializedLocal:
-    return {getAddrOfAnonymousContextDescriptor(from),
+    return {getAddrOfAnonymousContextDescriptor(
+              fromAnonymousContext ? parent : from),
             ConstantReference::Direct};
 
   case DeclContextKind::GenericTypeDecl:
     if (auto nomTy = dyn_cast<NominalTypeDecl>(parent)) {
       return {getAddrOfTypeContextDescriptor(nomTy, DontRequireMetadata),
               ConstantReference::Direct};
     }
-    return {getAddrOfAnonymousContextDescriptor(from),
+    return {getAddrOfAnonymousContextDescriptor(
+              fromAnonymousContext ? parent : from),
             ConstantReference::Direct};
 
   case DeclContextKind::ExtensionDecl: {

lib/IRGen/GenMeta.cpp

@@ -513,8 +513,8 @@ namespace {
     }
 
     ConstantReference getParent() {
-      return {IGM.getAddrOfModuleContextDescriptor(DC->getParentModule()),
-              ConstantReference::Direct};
+      return IGM.getAddrOfParentContextDescriptor(
+               DC, /*fromAnonymousContext=*/true);
     }
 
     ContextDescriptorKind getContextKind() {
@@ -565,7 +565,8 @@ namespace {
     }
 
     ConstantReference getParent() {
-      return IGM.getAddrOfParentContextDescriptor(Proto);
+      return IGM.getAddrOfParentContextDescriptor(
+               Proto, /*fromAnonymousContext=*/false);
     }
 
     ContextDescriptorKind getContextKind() {
@@ -1014,7 +1015,8 @@ namespace {
     }
 
     ConstantReference getParent() {
-      return IGM.getAddrOfParentContextDescriptor(Type);
+      return IGM.getAddrOfParentContextDescriptor(
+               Type, /*fromAnonymousContext=*/false);
     }
 
     GenericSignature *getGenericSignature() {

lib/IRGen/GenProto.cpp

@@ -1937,7 +1937,8 @@ namespace {
       auto moduleContext =
         normal->getDeclContext()->getModuleScopeContext();
       ConstantReference moduleContextRef =
-        IGM.getAddrOfParentContextDescriptor(moduleContext);
+        IGM.getAddrOfParentContextDescriptor(moduleContext,
+                                             /*fromAnonymousContext=*/false);
       B.addRelativeAddress(moduleContextRef);
     }
 

lib/IRGen/IRGenModule.h

@@ -1277,7 +1277,8 @@ private:                            \
                                       ConstantInit definition = ConstantInit());
   llvm::Constant *getAddrOfObjCModuleContextDescriptor();
   llvm::Constant *getAddrOfClangImporterModuleContextDescriptor();
-  ConstantReference getAddrOfParentContextDescriptor(DeclContext *from);
+  ConstantReference getAddrOfParentContextDescriptor(DeclContext *from,
+                                                     bool fromAnonymousContext);
   llvm::Constant *getAddrOfGenericEnvironment(CanGenericSignature signature);
   llvm::Constant *getAddrOfProtocolRequirementsBaseDescriptor(
                                                   ProtocolDecl *proto);

test/Runtime/associated_type_demangle_private.swift

@@ -18,6 +18,15 @@ fileprivate struct Foo {
   }
 }
 
+public struct Wibble<T> { }
+
+extension Wibble {
+  fileprivate struct Inner: P {
+    fileprivate struct Innermost { }
+    typealias A = (Innermost, T)
+  }
+}
+
 func getP_A<T: P>(_: T.Type) -> Any.Type {
   return T.A.self
 }
@@ -27,6 +36,7 @@ let AssociatedTypeDemangleTests = TestSuite("AssociatedTypeDemangle")
 
 AssociatedTypeDemangleTests.test("private types") {
   expectEqual(Foo.Inner.Innermost.self, getP_A(Foo.Inner.self))
+  expectEqual((Wibble<Float>.Inner.Innermost, Float).self, getP_A(Wibble<Float>.Inner.self))
 }
 
 private protocol P2 {

test/stdlib/RuntimeObjC.swift

@@ -760,10 +760,9 @@ RuntimeClassNamesTestSuite.test("private class nested in same-type-constrained e
   let util = base.asInner
 
   let clas = unsafeBitCast(type(of: util), to: NSObject.self)
-  // Name should look like _TtC1aP.*Inner
   let desc = clas.description
-  expectEqual("_TtGC1a", desc.prefix(7))
-  expectEqual("Data_", desc.suffix(5))
+  expectEqual("_TtCE1a", desc.prefix(7))
+  expectEqual("Inner", desc.suffix(5))
 }
 
 runAllTests()