[libcxx-commits] [libcxx] [libc++] Don't try to wait on a thread that hasn't started in std::async (PR #125433)

[Louis Dionne via libcxx-commits]

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ldionne wrote:

Please add a short comment explaining what this test is testing, including a link to the Github issue.

https://github.com/llvm/llvm-project/pull/125433