[clang] [libcxx] [libc++][Clang] Updated the diagnostics checks in libc++ tests. (PR #144220)

[Nikolas Klauser via cfe-commits]

https://github.com/philnik777 commented:

> Hi, @AaronBallman! I noticed that the libc++ tests are not using the latest version of my code. How can I run them with the latest version? Thank you!

They are being run with the current trunk, but also with older versions of Clang, because libc++ supports older versions. Assuming the changes are actually correct, you should be able to simply use `expected-error 0-1` to work around the different diagnostic behaviour in different Clang versions.

https://github.com/llvm/llvm-project/pull/144220