[clang] [Clang] Consider preferred_type in bitfield warnings (#116760) (PR #116785)

[Erich Keane via cfe-commits]

erichkeane wrote:

> @erichkeane @Fznamznon what should the release note be - just something akin to "added warning flag -W... to warn when bitfield packing differs from MSVC"?

Elaborate a bit more than that, but yes, something like that.  "Added warning flag -Wxxx that does...".  Some folks take a summary of their AttrDocs.td entry to make the description of what they did better.

https://github.com/llvm/llvm-project/pull/116785