https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93983
--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-10 branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>: https://gcc.gnu.org/g:566ba72126288272607374a32ac646dcd36fe584 commit r10-8163-g566ba72126288272607374a32ac646dcd36fe584 Author: Jonathan Wakely <jwak...@redhat.com> Date: Thu May 21 07:47:17 2020 +0100 libstdc++: Avoid constraint recursion with iterator_traits (PR 93983) Checking whether a filesystem::path constructor argument is an iterator requires instantiating std::iterator_traits. In C++20 that checks for satisfaction of std::iterator_traits constraints, which checks if the type is copyable, which can end up recursing back to the path constructor. The fix in LWG 3420 is to reorder the cpp17-iterator concept's constraints to check if the type looks vaguely like an iterator before checking copyable. That avoids the recursion for types which definitely aren't iterators, but isn't foolproof. Backport from mainline 2020-05-21 Jonathan Wakely <jwak...@redhat.com> PR libstdc++/93983 * include/bits/iterator_concepts.h (__detail::__cpp17_iterator): Reorder constraints to avoid recursion when constructors use iterator_traits (LWG 3420). * testsuite/24_iterators/customization_points/lwg3420.cc: New test.
