[clang] [Clang] Optimize -Wunsafe-buffer-usage. (PR #125492)

[Ziqing Luo via cfe-commits]

ziqingluo-90 wrote:

I don't have big concerns here.  Thank you again @ivanaivanovska and @ilya-biryukov for this effort!
It is also going to be easier to debug and will open more opportunities for optimization this way. (E.g., I'd like to optimize how "printf" functions are matched, but was holding back due to some issues with ASTMatchers.)

ASTMatchers are still great. They are more readable and succinct, but probably better suited for lightweight tasks.

https://github.com/llvm/llvm-project/pull/125492