[clang] [Clang] Fix Sema::checkArgCount for 0-arg functions (PR #139638)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> I have no idea how to check the range for the diagnostic here, and I don't think we actually have a way?

`-fdiagnostics-print-source-range-info` I believe?

https://github.com/llvm/llvm-project/pull/139638