diff --git a/libcxx/include/__format/format_arg_store.h b/libcxx/include/__format/format_arg_store.h --- a/libcxx/include/__format/format_arg_store.h +++ b/libcxx/include/__format/format_arg_store.h @@ -143,21 +143,24 @@ // // Note this version can't be constrained avoiding ambiguous overloads. // That means it can be instantiated by disabled formatters. To solve this, a -// constrained version for not formattable formatters is added. That overload -// is marked as deleted to fail creating a storage type for disabled formatters. +// constrained version for not formattable formatters is added. template consteval __arg_t __determine_arg_t() { return __arg_t::__handle; } +// The overload for not formattable types allows triggering the static +// assertion below. template requires(!__formattable<_Tp, typename _Context::char_type>) -consteval __arg_t __determine_arg_t() = delete; +consteval __arg_t __determine_arg_t() { + return __arg_t::__none; +} template _LIBCPP_HIDE_FROM_ABI basic_format_arg<_Context> __create_format_arg(_Tp&& __value) noexcept { constexpr __arg_t __arg = __determine_arg_t<_Context, remove_cvref_t<_Tp>>(); - static_assert(__arg != __arg_t::__none); + static_assert(__arg != __arg_t::__none, "the supplied type is not formattable"); // Not all types can be used to directly initialize the // __basic_format_arg_value. First handle all types needing adjustment, the