[libcxx-commits] [libcxx] [libc++] Make std::pair trivially copyable if its members are (PR #89652)

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EricWF wrote:

> @EricWF This is a pre-existing problem. `_LIBCPP_ABI_ENABLE_UNIQUE_PTR_TRIVIAL_ABI` and `_LIBCPP_ABI_ENABLE_SHARED_PTR_TRIVIAL_ABI` do the same thing, so I don't think this should be blocking for this PR. We basically don't support the unstable ABI and GCC currently.

Another couple of pointst:

* It's not the unstable ABI, it's ABI v2, which has been made unstable under GCC. 

I think the discussion should block this PR. If there's  no discussion to be had because other people don't care, then that's fine. But continuing to break things, because previous changes broke things before, is not convincing.

If there was a discussion at the time of the original commits about this, then we can move forward. But if there was no discussion, then it seems those breakages were done out of ignorance and they shouldn't be used as a shield here.


Now I expect we have few GCC users, and of those, most don't care about ABI stability. But again, ignorance here isn't a defence. 

@philnik777 Was this issues discussed on the previous changes? 


https://github.com/llvm/llvm-project/pull/89652