https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116641
--- Comment #1 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>: https://gcc.gnu.org/g:c07cf418fdde0c192e370a8d76a991cc7215e9c4 commit r15-3575-gc07cf418fdde0c192e370a8d76a991cc7215e9c4 Author: Jonathan Wakely <jwak...@redhat.com> Date: Tue Sep 10 14:25:41 2024 +0100 libstdc++: std::string move assignment should not use POCCA trait [PR116641] The changes to implement LWG 2579 (r10-327-gdb33efde17932f) made std::string::assign use the propagate_on_container_copy_assignment (POCCA) trait, for consistency with operator=(const basic_string&). However, this also unintentionally affected operator=(basic_string&&) which calls assign(str) to make a deep copy when performing a move is not possible. The fix is for the move assignment operator to call _M_assign(str) instead of assign(str), as this just does the deep copy and doesn't check the POCCA trait first. The bug only affects the unlikely/useless combination of POCCA==true and POCMA==false, but we should fix it for correctness anyway. it should also make move assignment slightly cheaper to compile and execute, because we skip the extra code in assign(const basic_string&). libstdc++-v3/ChangeLog: PR libstdc++/116641 * include/bits/basic_string.h (operator=(basic_string&&)): Call _M_assign instead of assign. * testsuite/21_strings/basic_string/allocator/116641.cc: New test.
