It should be sufficient to move only following to formatfwd.h to declare
disabled specialization for optional.
I do not think that we need to move to a partial specialization of
format_kind for ranges.
// [format.range], formatting of ranges
+ // [format.range.fmtkind], variable template format_kind
+ enum class range_format {
+ disabled,
+ map,
+ set,
+ sequence,
+ string,
+ debug_string
+ };
+
+ /** @brief A constant determining how a range should be formatted.
+ *
+ * The primary template of `std::format_kind` cannot be instantiated.
+ * There is a partial specialization for input ranges and you can
+ * specialize the variable template for your own cv-unqualified types
+ * that satisfy the `ranges::input_range` concept.
+ *
+ * @since C++23
+ */
+ template<typename _Rg>
+ constexpr auto format_kind = []{
+ static_assert(false, "cannot use primary template of
'std::format_kind'");
+ return type_identity<_Rg>{};
+ }();
You are not testing for the __cpp_lib_optional_range_support macro in the
test file.
And I would add a static_assert(!formattable<optional<int>>) to the tests.
On Tue, Jun 10, 2025 at 5:21 PM Giuseppe D'Angelo <giuseppe.dang...@kdab.com>
wrote:
> Hello,
>
> On 10/06/2025 16:32, Jonathan Wakely wrote:
> >> Whops, I again addedstd::string to a constexpr test, so this will fail
> >> on the old ABI. Should I change it to e.g.std::vector, or should I keep
> >> it and add a `{ dg-require-effective-target cxx11_abi }` directive?
> >
> > Would string_view work instead? If not, please change it to vector.
>
> Added both and removed string. New patch attached.
>
> Thank you,
>
> --
> Giuseppe D'Angelo
>
