[Bug c++/113191] [11/12/13/14 Regression] Incorrect overload resolution when base class function introduced with a using declaration is more constrained than a function declared in the derived class

["waffl3x at protonmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113191

--- Comment #2 from waffl3x <waffl3x at protonmail dot com> ---
> Looking at the above commit, joust already takes care to check
> more_constrained for non-template functions, and only if their function
> parameters match according to cand_parms_match.  But here cand_parms_match
> returns false due to different implicit object parameters:

Okay yeah I definitely misunderstood something in more_specialized_fn,
what it does works but is arguably not the right thing.

> (gdb) frame
> #0  cand_parms_match (c2=0x3402cc0, c1=0x3402d70) at gcc/cp/call.cc:12699
> 12699     if (DECL_FUNCTION_MEMBER_P (fn1)
> (gdb) pct parms1
> 
> struct B *, void
> 
> (gdb) pct parms2
> 
> struct S *, void
> 
> In contrast more_specialized_fn skips over the implicit object parameter
> when comparing two non-static memfns.  Maybe cand_parms_match should follow
> suit?

We COULD do that, but it won't solve the problems with implementing the
xobj/iobj cases. With that said it probably does make more sense to
skip the object parameter when comparing two iobj member functions. Are
there ever any situations where both candidates are viable, but have
different object parameters? I'm pretty sure that will never be the
case, right?

I guess I'll have to open another PR for the xobj/iobj cases because I
think I agree with your evaluation of this.