[Bug libstdc++/99402] [10/11 Regression] std::copy creates _GLIBCXX_DEBUG false positive for attempt to subscript a dereferenceable (start-of-sequence) iterator

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99402

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This causes __valid_range to return {11, __dp_sign_max_size} and then we check
__result._M_can_advance(11) which fails.

We don't want to advance the result by the size of the other sequence, only by
distance(__first, __last). We don't care if there are elements in the sequence
past __last because we're not trying to copy them.