Simplify byte handling

include/fmt/core.h

@@ -8,7 +8,6 @@
 #ifndef FMT_CORE_H_
 #define FMT_CORE_H_
 
-#include <cstddef>  // std::byte
 #include <cstdio>   // std::FILE
 #include <cstring>
 #include <iterator>
@@ -367,12 +366,6 @@ FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
 #  endif
 #endif
 
-#ifdef __cpp_lib_byte
-using byte = std::byte;
-#else
-enum class byte : unsigned char {};
-#endif
-
 #if defined(FMT_USE_STRING_VIEW)
 template <typename Char> using std_string_view = std::basic_string_view<Char>;
 #elif defined(FMT_USE_EXPERIMENTAL_STRING_VIEW)
@@ -1429,10 +1422,6 @@ template <typename Context> struct arg_mapper {
     return map(format_as(val));
   }
 
-  FMT_CONSTEXPR FMT_INLINE auto map(detail::byte val) -> unsigned {
-    return map(static_cast<unsigned char>(val));
-  }
-
   template <typename T, typename U = remove_cvref_t<T>>
   struct formattable
       : bool_constant<has_const_formatter<U, Context>() ||