[clang] [clang][PAC] Support trivially_relocating polymorphic objects (PR #144420)

[John McCall via cfe-commits]

https://github.com/rjmccall commented:

If it's not a bitwise copy, it's by definition not a trivial relocation, so I don't think this works. I think you're arguing for some kind of intermediate "non-failing relocation" feature.

Are we really reporting polymorphic class types as trivially relocatable?

https://github.com/llvm/llvm-project/pull/144420