[libcxx-commits] [libcxx] [libc++] Document our ABI guarantees and what ABI flags exist to modify these guarantees (PR #132615)

[Louis Dionne via libcxx-commits]

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+libc++'s ABI Guarantees
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ldionne wrote:

Our ABI macros are intended to be used by vendors, not by users. I think that is where we should document them and I think we should word that documentation with that in mind.

We should *not* document these ABI macros in any location that makes them look as if users can modify them. I actually see users defining ABI macros they shouldn't define on a regular basis, only to wonder why their code suddenly starts breaking when they trip up an ABI landmine. We could potentially also clarify that those are "internal" macros by changing their name to include something like `INTERNAL`, or `IMPL`, or `VENDOR`.

https://github.com/llvm/llvm-project/pull/132615