[clang] [clang] odr-checker fix for conversion operators (PR #146153)

[Maksim Ivanov via cfe-commits]

https://github.com/emaxx-google approved this pull request.

Thanks! I don't know if similar problems (ODR confused by the canonicalization merging decltypes with different names of template parameters) can show up in other cases, but as the PR fixes this particular case LGTM.

https://github.com/llvm/llvm-project/pull/146153