https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109751
Bug ID: 109751
Summary: boost interface_interface fails concept check starting
in gcc-13
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: ldalessandro at gmail dot com
Target Milestone: ---
The following example is reduced from
https://github.com/boostorg/stl_interfaces/blob/boost-1.82.0/example/node_iterator.cpp.
It compiles fine in gcc-12 but fails a concept check in gcc-13.
#include <boost/stl_interfaces/iterator_interface.hpp>
template<typename T>
struct iterator : boost::stl_interfaces::iterator_interface<iterator<T>,
std::forward_iterator_tag, T>
{
using base_type = boost::stl_interfaces::iterator_interface<iterator<T>,
std::forward_iterator_tag, T>;
using base_type::operator++;
T& operator*() const;
iterator& operator++();
bool operator==(iterator) const;
};
static_assert(std::incrementable<iterator<int>>);
Live: https://godbolt.org/z/6qsx1narj
The error tells us that this requires clause changes from false to true.
friend constexpr bool operator<(D lhs, D rhs)
requires std::equality_comparable<D> {
return (lhs - rhs) < typename D::difference_type(0);
}
https://github.com/boostorg/stl_interfaces/blob/boost-1.82.0/include/boost/stl_interfaces/iterator_interface.hpp#L779
I don't think that requires clause makes any sense, but I also don't know why
the behavior would have changed from gcc-12 to gcc-13.
