Fix formatting of std::byte via format_as

include/fmt/core.h

@@ -8,6 +8,7 @@
 #ifndef FMT_CORE_H_
 #define FMT_CORE_H_
 
+#include <cstddef>  // std::byte
 #include <cstdio>   // std::FILE
 #include <cstring>  // std::strlen
 #include <iterator>
@@ -1275,6 +1276,12 @@ enum { long_short = sizeof(long) == sizeof(int) };
 using long_type = conditional_t<long_short, int, long long>;
 using ulong_type = conditional_t<long_short, unsigned, unsigned long long>;
 
+#ifdef __cpp_lib_byte
+inline auto format_as(std::byte b) -> unsigned char {
+  return static_cast<unsigned char>(b);
+}
+#endif
+
 // Maps formatting arguments to core types.
 // arg_mapper reports errors by returning unformattable instead of using
 // static_assert because it's used in the is_formattable trait.

include/fmt/format.h

@@ -34,7 +34,6 @@
 #define FMT_FORMAT_H_
 
 #include <cmath>         // std::signbit
-#include <cstddef>       // std::byte
 #include <cstdint>       // uint32_t
 #include <cstring>       // std::memcpy
 #include <limits>        // std::numeric_limits
@@ -2997,11 +2996,6 @@ constexpr auto format_as(Enum e) noexcept -> underlying_t<Enum> {
 }
 }  // namespace enums
 
-#ifdef __cpp_lib_byte
-inline auto format_as(std::byte b) -> unsigned char { return underlying(b); }
-FMT_FORMAT_AS(std::byte, unsigned char);
-#endif
-
 class bytes {
  private:
   string_view data_;