From 4f39d88650314bdfe7968bd3d4d082a6ddb085b9 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <viz@meta.com>
Date: Sun, 1 Sep 2024 18:24:24 -0700
Subject: [PATCH] Cleanup base API

---
 include/fmt/base.h   | 15 +++++----------
 include/fmt/format.h |  4 ++++
 include/fmt/printf.h |  4 ++--
 3 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/include/fmt/base.h b/include/fmt/base.h
index e37b80c7..f9908941 100644
--- a/include/fmt/base.h
+++ b/include/fmt/base.h
@@ -657,7 +657,6 @@ using buffered_context =
     conditional_t<std::is_same<Char, char>::value, context,
                   generic_context<basic_appender<Char>, Char>>;
 
-template <typename Context> struct arg_mapper;
 FMT_EXPORT template <typename Context> class basic_format_arg;
 FMT_EXPORT template <typename Context> class basic_format_args;
 FMT_EXPORT template <typename Context> class dynamic_format_arg_store;
@@ -694,6 +693,11 @@ struct has_to_string_view<
     T, void_t<decltype(detail::to_string_view(std::declval<T>()))>>
     : std::true_type {};
 
+/// String's character (code unit) type. detail:: is intentional to prevent ADL.
+template <typename S,
+          typename V = decltype(detail::to_string_view(std::declval<S>()))>
+using char_t = typename V::value_type;
+
 template <typename Char>
 using unsigned_char = typename conditional_t<std::is_integral<Char>::value,
                                              std::make_unsigned<Char>,
@@ -825,11 +829,6 @@ FMT_DEPRECATED FMT_NORETURN inline void throw_format_error(
   report_error(message);
 }
 
-/// String's character (code unit) type.
-template <typename S,
-          typename V = decltype(detail::to_string_view(std::declval<S>()))>
-using char_t = typename V::value_type;
-
 enum class presentation_type : unsigned char {
   // Common specifiers:
   none = 0,
@@ -2098,10 +2097,6 @@ template <typename T> struct format_as_result {
 };
 template <typename T> using format_as_t = typename format_as_result<T>::type;
 
-template <typename T>
-struct has_format_as
-    : bool_constant<!std::is_same<format_as_t<T>, void>::value> {};
-
 #define FMT_MAP_API static FMT_CONSTEXPR FMT_ALWAYS_INLINE
 
 // Maps formatting arguments to reduce the set of types we need to work with.
diff --git a/include/fmt/format.h b/include/fmt/format.h
index a750c9f6..ec94d55b 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -3820,6 +3820,10 @@ FMT_API void format_error_code(buffer<char>& out, int error_code,
 using fmt::report_error;
 FMT_API void report_error(format_func func, int error_code,
                           const char* message) noexcept;
+
+template <typename T>
+struct has_format_as
+    : bool_constant<!std::is_same<format_as_t<T>, void>::value> {};
 }  // namespace detail
 
 FMT_BEGIN_EXPORT
diff --git a/include/fmt/printf.h b/include/fmt/printf.h
index 8a130118..7eccc0a7 100644
--- a/include/fmt/printf.h
+++ b/include/fmt/printf.h
@@ -618,7 +618,7 @@ inline auto vsprintf(basic_string_view<Char> fmt,
  *
  *     std::string message = fmt::sprintf("The answer is %d", 42);
  */
-template <typename S, typename... T, typename Char = char_t<S>>
+template <typename S, typename... T, typename Char = detail::char_t<S>>
 inline auto sprintf(const S& fmt, const T&... args) -> std::basic_string<Char> {
   return vsprintf(detail::to_string_view(fmt),
                   fmt::make_format_args<basic_printf_context<Char>>(args...));
@@ -643,7 +643,7 @@ inline auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
  *
  *     fmt::fprintf(stderr, "Don't %s!", "panic");
  */
-template <typename S, typename... T, typename Char = char_t<S>>
+template <typename S, typename... T, typename Char = detail::char_t<S>>
 inline auto fprintf(std::FILE* f, const S& fmt, const T&... args) -> int {
   return vfprintf(f, detail::to_string_view(fmt),
                   make_printf_args<Char>(args...));