[libcxx-commits] [libcxx] [libc++] Fix ABI break introduced by switching to _LIBCPP_COMPRESSED_PAIR (PR #154686)

[Louis Dionne via libcxx-commits]

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ldionne wrote:

General comment: we need to add a release note. Let's add it to 21.rst since we will be landing this onto that branch.

The release note needs to mention the minor breakage to `unique_ptr` in constexpr.

The commit message should summarize the issue (with a link to the actual GH issue with all the details) and should explain how the fix works. You can base it on https://github.com/llvm/llvm-project/issues/154146#issuecomment-3210926293 if you feel that's helpful.

https://github.com/llvm/llvm-project/pull/154686