[clang] [clang] check deduction consistency when partial ordering function templates (PR #100692)

[Alexander Kornienko via cfe-commits]

alexfh wrote:

> However, I suspect that the parentheses reduction and the one with a ternary are actually the same issue - The code is IFNDR per https://eel.is/c++draft/temp.over.link#5
> 
> In you last example, M*2 and the conditional with M+N after the substitution of the default argument aren't equivalent despite having the same value after instantiation.

Actually, I'm not sure the code I provided as "a bit closer to the original" is actually close enough to retain the relevant properties. I'll try to look at the original code to see if it actually is IFNDR according to https://eel.is/c++draft/temp.over.link#5. It's going to take some time though.

https://github.com/llvm/llvm-project/pull/100692