Reland: [clang] preserve class type sugar when taking pointer to member (#132234)

Original PR: #130537
Reland after updating lldb too.

This changes the MemberPointerType representation to use a
NestedNameSpecifier instead of a Type to represent the base class.

Since the qualifiers are always parsed as nested names, there was an
impedance mismatch when converting these back and forth into types, and
this led to issues in preserving sugar.

The nested names are indeed a better match for these, as the differences
which a QualType can represent cannot be expressed syntatically, and
they represent the use case more exactly, being either dependent or
referring to a CXXRecord, unqualified.

This patch also makes the MemberPointerType able to represent sugar for
a {up/downcast}cast conversion of the base class, although for now the
underlying type is canonical, as preserving the sugar up to that point
requires further work.

As usual, includes a few drive-by fixes in order to make use of the
improvements.

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 2af692d..257b7b4 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -2667,7 +2667,7 @@ void CodeGenModule::SetLLVMFunctionAttributesForDefinition(const Decl *D,
     for (const CXXRecordDecl *Base : getMostBaseClasses(MD->getParent())) {
       llvm::Metadata *Id =
           CreateMetadataIdentifierForType(Context.getMemberPointerType(
-              MD->getType(), Context.getRecordType(Base).getTypePtr()));
+              MD->getType(), /*Qualifier=*/nullptr, Base));
       F->addTypeMetadata(0, Id);
     }
   }