https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112477
--- Comment #5 from Dave Martin <dave.martin at giref dot ulaval.ca> --- (In reply to Jonathan Wakely from comment #4) > Because in C++11 any use of a singular iterator, even copying it, was > undefined behaviour. The debug mode checks have not been properly updated to > reflect the relaxed preconditions in more recent standards. I'm a little confused by your response. I recently found this change in our test suite when we updated our compilers. Our code works fine in gcc 12.3 but returns the copy-construct error in 13.2 (as shown in the godbolt example), both using C++17. Are you saying the debug mode of gcc 13.2 has not been properly updated to reflect the changes in C++17? Because, from my understanding, gcc 13.2 added a check that restrains the preconditions. In other words, you seem to be saying that 13.2 was not updated to relax the preconditions, but the behaviour I am seeing is that 13.2 added a restraint on the preconditions. I think the change comes from this commit: https://github.com/gcc-mirror/gcc/commit/01b1afdc35c13cbff5cd3d37f9319285ab84b157
