[clang] [clang] Enable C++17 relaxed template template argument matching by default (PR #89807)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

> Would it be reasonable to add a `-Wno-deprecated-relaxed-template-template-args` flag (or something like that) for this specific deprecation?

I had similar idea, but what about instead implementing something generic to ignore deprecation of any driver flag?

https://github.com/llvm/llvm-project/pull/89807