https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116162
--- Comment #8 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:a2746e4347076ea48f4aeb28e13e6337ff7799ad commit r15-3721-ga2746e4347076ea48f4aeb28e13e6337ff7799ad Author: Marek Polacek <pola...@redhat.com> Date: Mon Sep 9 14:23:33 2024 -0400 c++: deleting explicitly-defaulted functions [PR116162] This PR points out the we're not implementing [dcl.fct.def.default] properly. Consider e.g. struct C { C(const C&&) = default; }; where we wrongly emit an error, but the move ctor should be just =deleted. According to [dcl.fct.def.default], if the type of the special member function differs from the type of the corresponding special member function that would have been implicitly declared in a way other than as allowed by 2.1-4, the function is defined as deleted. There's an exception for assignment operators in which case the program is ill-formed. clang++ has a warning for when we delete an explicitly-defaulted function so this patch adds it too. When the code is ill-formed, we emit an error in all modes. Otherwise, we emit a pedwarn in C++17 and a warning in C++20. PR c++/116162 gcc/c-family/ChangeLog: * c.opt (Wdefaulted-function-deleted): New. gcc/cp/ChangeLog: * class.cc (check_bases_and_members): Don't set DECL_DELETED_FN here, leave it to defaulted_late_check. * cp-tree.h (maybe_delete_defaulted_fn): Declare. (defaulted_late_check): Add a tristate parameter. * method.cc (maybe_delete_defaulted_fn): New. (defaulted_late_check): Add a tristate parameter. Call maybe_delete_defaulted_fn instead of giving an error. gcc/ChangeLog: * doc/invoke.texi: Document -Wdefaulted-function-deleted. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/defaulted15.C: Add dg-warning/dg-error. * g++.dg/cpp0x/defaulted51.C: Likewise. * g++.dg/cpp0x/defaulted52.C: Likewise. * g++.dg/cpp0x/defaulted53.C: Likewise. * g++.dg/cpp0x/defaulted54.C: Likewise. * g++.dg/cpp0x/defaulted56.C: Likewise. * g++.dg/cpp0x/defaulted57.C: Likewise. * g++.dg/cpp0x/defaulted58.C: Likewise. * g++.dg/cpp0x/defaulted59.C: Likewise. * g++.dg/cpp0x/defaulted63.C: New test. * g++.dg/cpp0x/defaulted64.C: New test. * g++.dg/cpp0x/defaulted65.C: New test. * g++.dg/cpp0x/defaulted66.C: New test. * g++.dg/cpp0x/defaulted67.C: New test. * g++.dg/cpp0x/defaulted68.C: New test. * g++.dg/cpp0x/defaulted69.C: New test. * g++.dg/cpp23/defaulted1.C: New test.
