Fix template argument ordering

Author: vitaut

include/fmt/args.h

@@ -114,7 +114,7 @@ FMT_EXPORT template <typename Context> class dynamic_format_arg_store {
   }
 
   template <typename T>
-  void emplace_arg(const detail::named_arg<char_type, T>& arg) {
+  void emplace_arg(const detail::named_arg<T, char_type>& arg) {
     if (named_info_.empty())
       data_.insert(data_.begin(), basic_format_arg<Context>(nullptr, 0));
     data_.emplace_back(detail::unwrap(arg.value));
@@ -184,7 +184,7 @@ FMT_EXPORT template <typename Context> class dynamic_format_arg_store {
    * copying of the argument. The name is always copied into the store.
    */
   template <typename T>
-  void push_back(const detail::named_arg<char_type, T>& arg) {
+  void push_back(const detail::named_arg<T, char_type>& arg) {
     const char_type* arg_name =
         dynamic_args_.push<std::basic_string<char_type>>(arg.name).c_str();
     if FMT_CONSTEXPR20 (need_copy<T>::value) {

include/fmt/base.h

@@ -1031,14 +1031,14 @@ struct is_view : std::false_type {};
 template <typename T>
 struct is_view<T, bool_constant<sizeof(T) != 0>> : std::is_base_of<view, T> {};
 
-template <typename Char, typename T> struct named_arg;
+template <typename T, typename Char> struct named_arg;
 template <typename T> struct is_named_arg : std::false_type {};
 template <typename T> struct is_static_named_arg : std::false_type {};
 
 template <typename Char, typename T>
-struct is_named_arg<named_arg<Char, T>> : std::true_type {};
+struct is_named_arg<named_arg<T, Char>> : std::true_type {};
 
-template <typename Char, typename T> struct named_arg : view {
+template <typename T, typename Char = char> struct named_arg : view {
   const Char* name;
   const T& value;
 
@@ -2719,7 +2719,7 @@ using vargs =
  * sufficiently new compilers. See `operator""_a()`.
  */
 template <typename Char, typename T>
-inline auto arg(const Char* name, const T& arg) -> detail::named_arg<Char, T> {
+inline auto arg(const Char* name, const T& arg) -> detail::named_arg<T, Char> {
   return {name, arg};
 }
 

include/fmt/format.h

@@ -3861,7 +3861,7 @@ struct udl_arg {
 template <typename Char> struct udl_arg {
   const Char* str;
 
-  template <typename T> auto operator=(T&& value) const -> named_arg<Char, T> {
+  template <typename T> auto operator=(T&& value) const -> named_arg<T, Char> {
     return {str, std::forward<T>(value)};
   }
 };

include/fmt/ranges.h

@@ -760,8 +760,7 @@ template <typename Container> struct all {
  * formatted as the underlying container.
  */
 FMT_EXPORT
-template <typename T>
-struct is_container_adaptor {
+template <typename T> struct is_container_adaptor {
  private:
   template <typename U> static auto check(U* p) -> typename U::container_type;
   template <typename> static void check(...);