[clang-tools-extra] [clang-tidy] suggest fix it hints for string concat (PR #188430)

[Zeyi Xu via cfe-commits]

zeyi2 wrote:

The current diff is a bit difficult to review, so I need more time to evaluate the correctness.

Also please add a ReleaseNotes entry.

https://github.com/llvm/llvm-project/pull/188430