[Bug c++/115239] [14 Regression] ICE: Segmentation fault with ambiguous function call in some cases (`const char*` vs `char` with `long` vs `unsigned`) since r14-6522

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115239

--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-14 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:4df86402990e2f45e02a367f1734a22ebc041e98

commit r14-10319-g4df86402990e2f45e02a367f1734a22ebc041e98
Author: Patrick Palka <ppalka@redhat.com>
Date:   Thu Jun 13 10:02:43 2024 -0400

    c++: ICE w/ ambig and non-strictly-viable cands [PR115239]

    Here during overload resolution we have two strictly viable ambiguous
    candidates #1 and #2, and two non-strictly viable candidates #3 and #4
    which we hold on to ever since r14-6522.  These latter candidates have
    an empty second arg conversion since the first arg conversion was deemed
    bad, and this trips up joust when called on #3 and #4 which assumes all
    arg conversions are there.

    We can fix this by making joust robust to empty arg conversions, but in
    this situation we shouldn't need to compare #3 and #4 at all given that
    we have a strictly viable candidate.  To that end, this patch makes
    tourney shortcut considering non-strictly viable candidates upon
    encountering ambiguity between two strictly viable candidates (taking
    advantage of the fact that the candidates list is sorted according to
    viability via splice_viable).

            PR c++/115239

    gcc/cp/ChangeLog:

            * call.cc (tourney): Don't consider a non-strictly viable
            candidate as the champ if there was ambiguity between two
            strictly viable candidates.

    gcc/testsuite/ChangeLog:

            * g++.dg/overload/error7.C: New test.

    Reviewed-by: Jason Merrill <jason@redhat.com>
    (cherry picked from commit 7fed7e9bbc57d502e141e079a6be2706bdbd4560)