[libcxx-commits] [libcxx] [libc++] Ensure that `std::expected` has no tail padding (PR #69673)

[Michał Górny via libcxx-commits]

mgorny wrote:

I think Gentoo has some users of libc++ setup that could be affected by this (we consider this setup experimental, so we don't do "stable" releases there, so they probably upgraded to 17.x already).

My personal preference would be to make it experimental again. If something's affected, I'd rather have it break verbosely on next build rather than silently start misbehaving.

As for the permanent solution, I suppose it wouldn't be possible to employ some namespace magic to expose two versions of the class, one preserving compatibility with the old ABI (and slow), and another exposing the new ABI?

https://github.com/llvm/llvm-project/pull/69673