https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115215
Bug ID: 115215 Summary: views::concat rejects non-movable references Product: gcc Version: 15.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ Assignee: unassigned at gcc dot gnu.org Reporter: hewillk at gmail dot com Target Milestone: --- libstdc++'s views::concat always requires concat_view(rs...) to be well-formed which does not fully conform with the wording as R does not need to satisfy concatable when there only one pack: #include <ranges> #include <format> int main() { auto r = std::views::iota(0, 5) | std::views::transform([](int) { return std::format_parse_context{""}; }); auto c = std::views::concat(r); // should be well-formed } https://godbolt.org/z/WG5TdsEce