https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95322
Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Ever confirmed|0 |1 Last reconfirmed| |2020-05-26 Keywords| |rejects-valid --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- I think it's a defect in the standard, the sentinel for transform_view can only be compared to iterators of the same constness: friend constexpr bool operator==(const _Iterator<_Const>& __x, const _Sentinel& __y) { return __y.__equal(__x); } I think it should work though.