[clang] [Sema] Fix an out-of-bounds crash when diagnosing bad conversion for a function with a parameter pack. (PR #92721)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

Can you add some details to the summary. What was the original code doing wrong and the proposed new approach.

https://github.com/llvm/llvm-project/pull/92721