[Bug c++/119906] New: error: '' in namespace 'std' does not name a type

[hewillk at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119906

            Bug ID: 119906
           Summary: error: '<expression error>' in namespace 'std' does
                    not name a type
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

Not sure if there is already a similar duplicate.

https://godbolt.org/z/W8sbx3hnn

#include <ranges>
#include <type_traits>

template<class R>
struct view {
  R r;
  static constexpr bool empty_r =
    decltype([](R& r) -> std::bool_constant<std::ranges::size(r) == 0> {
      return {};
    }(std::declval<R&>())){};
};

static_assert(
  view<std::ranges::empty_view<int>>::empty_r);