https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106675
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-12 branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:1721d85708116a1edbe5ba30f055d47e6c1e29b6 commit r12-9174-g1721d85708116a1edbe5ba30f055d47e6c1e29b6 Author: Marek Polacek <pola...@redhat.com> Date: Fri Feb 10 17:26:57 2023 -0500 c++: fix ICE in joust_maybe_elide_copy [PR106675] joust_maybe_elide_copy checks that the last conversion in the ICS for the first argument is ck_ref_bind, which is reasonable, because we've checked that we're dealing with a copy/move constructor. But it can also happen that we couldn't figure out which conversion function is better to convert the argument, as in this testcase: joust couldn't decide if we should go with operator foo &() or operator foo const &() so we get a ck_ambig, which then upsets joust_maybe_elide_copy. Since a ck_ambig can validly occur, I think we should just return early, as in the patch below. PR c++/106675 gcc/cp/ChangeLog: * call.cc (joust_maybe_elide_copy): Return false for ck_ambig. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/overload-conv-5.C: New test. (cherry picked from commit cce62625025380c2ea2a220deb10f8f355f83abf)