[clang-tools-extra] [clang-tidy][NFC] Add test for redundant-parentheses on reference NTTPs (PR #233514)

[Yanzuo Liu via cfe-commits]

zwuis wrote:

I think the case _is_ related to the original repro. The only difference is how synthetic parentheses around `DeclRefExpr` are used, which I don't care about. I'd suggest adding tests where the parentheses are synthesized via different call sites of `ParentExpr::Create` to improve test coverage.

Not blocking this PR, but I'll let other reviewers decide whether to approve.

https://github.com/llvm/llvm-project/pull/233514