[LLDB] Don't ignore artificial variables and members for coroutines

* always populate all fields for the generated coroutine frame type;
* make the artificial variables `__promise`, `__coro_frame` visible, so
  that they are present in the `frame var` command;

Author: hokein

lldb/source/Plugins/LanguageRuntime/CPlusPlus/CPPLanguageRuntime.cpp

@@ -41,7 +41,10 @@ CPPLanguageRuntime::CPPLanguageRuntime(Process *process)
     : LanguageRuntime(process) {}
 
 bool CPPLanguageRuntime::IsAllowedRuntimeValue(ConstString name) {
-  return name == g_this;
+  // FIXME: use a list when the list grows more.
+  return name == g_this ||
+         name == ConstString("__promise") ||
+         name == ConstString("__coro_frame");
 }
 
 bool CPPLanguageRuntime::GetObjectDescription(Stream &str,

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

@@ -3061,7 +3061,8 @@ void DWARFASTParserClang::ParseSingleMember(
   // artificial member with (unnamed bitfield) padding.
   // FIXME: This check should verify that this is indeed an artificial member
   // we are supposed to ignore.
-  if (attrs.is_artificial) {
+  if (attrs.is_artificial &&
+      !TypeSystemClang::IsCoroutineFrameType(class_clang_type)) {
     last_field_info.SetIsArtificial(true);
     return;
   }

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp

@@ -771,6 +771,10 @@ TypeSystemClang *TypeSystemClang::GetASTContext(clang::ASTContext *ast) {
   return clang_ast;
 }
 
+bool TypeSystemClang::IsCoroutineFrameType(const CompilerType &Type) {
+  return Type.GetTypeName().GetStringRef().ends_with(".coro_frame_ty");
+}
+
 clang::MangleContext *TypeSystemClang::getMangleContext() {
   if (m_mangle_ctx_up == nullptr)
     m_mangle_ctx_up.reset(getASTContext().createMangleContext());

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.h

@@ -154,6 +154,9 @@ class TypeSystemClang : public TypeSystem {
 
   static TypeSystemClang *GetASTContext(clang::ASTContext *ast_ctx);
 
+  // Returns true if the given type is a coroutine frame debug type.
+  static bool IsCoroutineFrameType(const CompilerType &Type);
+
   /// Returns the display name of this TypeSystemClang that indicates what
   /// purpose it serves in LLDB. Used for example in logs.
   llvm::StringRef getDisplayName() const { return m_display_name; }