Specialization of fmt::formatter followed by inclusion of <ostream.h> rejected by gcc

[lubgr]

The following snippet fails to compile with any recent gcc version.

#include <type_traits>
#include <fmt/format.h>

struct Test {};

namespace fmt {
   template<>
      struct formatter<Test> : formatter<int> {
         template <typename FormatContext>
            auto format(const Test&, FormatContext &ctx) {
               return formatter<int>::format(42, ctx);
            }
      };
}

// When moved on top of the specialization, it works fine:
#include <fmt/ostream.h>

The error message is

fmt/ostream.h:115:45: error: partial specialization of 'struct fmt::v5::convert_to_int<T, Char, void>' after instantiation of 'struct fmt::v5::convert_to_int<int, char, void>' [-fpermissive]
template <typename T, typename Char> struct convert_to_int<T, Char, void> {

Contrary, clang happily compiles this. See godbolt.

Thanks in advance for having a look! I could also try to fix it, but not today at least :)

[vitaut]

Fixed in 5efb24d, thanks for reporting!

[lubgr]

Awesome, thanks for fixing it immediately!