[clang] [llvm] [Clang] Correct __builtin_dynamic_object_size for subobject types (PR #78526)

[Nikita Popov via cfe-commits]

nikic wrote:

Thanks for summarizing, that matches my understanding.

As to how to implement this "properly", that would probably be https://discourse.llvm.org/t/exploring-the-effects-and-uses-of-the-memory-region-declaration-intrinsic/72756. The memory.region.decl intrinsics effectively encode subobjects. However, doing this has some fairly substantial externalities.

https://github.com/llvm/llvm-project/pull/78526