[clang] [Clang][Sema] Fix lookup of dependent operator= named by using-declaration (PR #91503)

[Paul Osmialowski via cfe-commits]

pawosm-arm wrote:

I'm sorry, I didn't notice that there is more discussion after #90152 covering also my issue at hand. The obvious advice I can get from those is the 'this is not valid c++, fix your code' suggestion. Trouble starts when there is a lot of it to fix, even if it mostly involve deletion of the functions that aren't instantiated.


https://github.com/llvm/llvm-project/pull/91503