Move to detail namespace

Author: jeremy-rifkin

include/fmt/std.h

@@ -713,6 +713,7 @@ template <typename T, typename Char> struct formatter<std::complex<T>, Char> {
   }
 };
 
+namespace detail {
 template <typename T, typename Enable = void>
 struct has_format_as : std::false_type {};
 template <typename T>
@@ -725,15 +726,15 @@ template <typename T>
 struct has_format_as_member<
     T, void_t<decltype(formatter<T>::format_as(std::declval<const T&>()))>>
     : std::true_type {};
+}  // namespace detail
 
 // Guard against format_as because reference_wrappers are implicitly convertible
 // to T&
-
 template <typename T, typename Char>
-struct formatter<
-    std::reference_wrapper<T>, Char,
-    enable_if_t<is_formattable<remove_cvref_t<T>, Char>::value &&
-                !has_format_as<T>::value && !has_format_as_member<T>::value>>
+struct formatter<std::reference_wrapper<T>, Char,
+                 enable_if_t<is_formattable<remove_cvref_t<T>, Char>::value &&
+                             !detail::has_format_as<T>::value &&
+                             !detail::has_format_as_member<T>::value>>
     : formatter<remove_cvref_t<T>, Char> {
   template <typename FormatContext>
   auto format(std::reference_wrapper<T> ref, FormatContext& ctx) const