https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115285
--- Comment #15 from frs.dumont at gmail dot com --- On 05/11/2024 18:18, redi at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115285 > > --- Comment #14 from Jonathan Wakely <redi at gcc dot gnu.org> --- > We're assuming that an iterator's reference type can be converted to the > key_type. This doesn't compile on trunk: > > #include <unordered_set> > > struct K { > explicit K(int) noexcept { } > bool operator==(const K&) const { return true; } > }; > > template<> struct std::hash<K> { > auto operator()(const K&) const { return 0ul; } > }; > > int i[1]; > std::unordered_set<K> s(i, i+1); > > > This fails for similar reasons: > > #include <unordered_map> > > struct K { > explicit K(int) noexcept { } > bool operator==(const K&) const { return true; } > }; It's surprising that we need to handle this use case. The user wants K is to be explicitly built from int but then insert ints, weird. Are other Standard library handling this ? You know C++ Standard much better than I do though.
