Created attachment 53472 [details] short repro Attached is a small reproducer of something that originally came from boost::system::error_code. g++ from v11 onward crashes on it: https://godbolt.org/z/nYqo1zj31
(In reply to Isabella from comment #0) > g++ from v11 onward crashes on it: https://godbolt.org/z/nYqo1zj31 That is because the language default changed to gnu++17 from gnu++14. Confirmed. It might be considered a regression even though it was rejected before GCC 8.4.0. The ICE is in joust_maybe_elide_copy.
I suspect the patch for PR 86521 which was aiming on fixing the rejection was not fully correct and introduced an ICE in some cases ...
Likely started with r9-6526-gdcfa8518868d9eb8 with -std=c++17.
The trunk branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>: https://gcc.gnu.org/g:cce62625025380c2ea2a220deb10f8f355f83abf commit r13-5990-gcce62625025380c2ea2a220deb10f8f355f83abf Author: Marek Polacek <polacek@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.
The releases/gcc-12 branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>: https://gcc.gnu.org/g:1721d85708116a1edbe5ba30f055d47e6c1e29b6 commit r12-9174-g1721d85708116a1edbe5ba30f055d47e6c1e29b6 Author: Marek Polacek <polacek@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)
The releases/gcc-11 branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>: https://gcc.gnu.org/g:53512f0055186d5556e9859c1f8beb25d2d28530 commit r11-10525-g53512f0055186d5556e9859c1f8beb25d2d28530 Author: Marek Polacek <polacek@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.c (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)
Fixed.