[clang] [Clang] Diagnose down casting static_cast (PR #117914)

[Congcong Cai via cfe-commits]

HerrCai0907 wrote:

> I'm a little bit worried about the behavior of the C++ Core Guideline check in clang-tidy though as it's now wholly redundant
I think the checker can be removed if clang has this kind of compilation time warning and can totally cover the checker.

> IMO, this is useful as on-by-default, but under its own flag. I haven't looked at the 'diff' yet, but that is my thoughts on it.
Then how to handle this downcast with RTTI support?


https://github.com/llvm/llvm-project/pull/117914