[clang] [clang] Fix unresolved overloaded conversion function reference (PR #230806)

[Younan Zhang via cfe-commits]

zyn0217 wrote:

Okay, so I looked closer and I think the underlying issue lurks somewhere else:

https://godbolt.org/z/j6KdbKhcs

So if there is a 'target' type, we can correctly rule out the template candidates - which means a simple discarded expression (`&S::operator int`) doesn't seem to lead to deducing template arguments, which is probably why the template candidate survives.

https://github.com/llvm/llvm-project/pull/230806