[clang] [clang] Implement constexpr bit_cast for vectors (PR #66894)

[Richard Smith via cfe-commits]

https://github.com/zygoloid commented:

Thanks, this looks good to me other than a small test coverage (see comment) / diagnostic wording issue.

(For future reference, please don't force-push to PR branches; that makes it much harder for your reviewer to see what's changed since their last review and can cause github to lose track of comments. See https://llvm.org/docs/GitHub.html#updating-pull-requests)

https://github.com/llvm/llvm-project/pull/66894