Consolidate implementation details

include/fmt/std.h

@@ -23,7 +23,6 @@
 #  include <type_traits>
 #  include <typeinfo>
 #  include <utility>
-#  include <vector>
 
 // Check FMT_CPLUSPLUS to suppress a bogus warning in MSVC.
 #  if FMT_CPLUSPLUS >= 201703L
@@ -79,11 +78,11 @@
 #  endif
 #endif
 
-#if FMT_CPP_LIB_FILESYSTEM
 FMT_BEGIN_NAMESPACE
-
 namespace detail {
 
+#if FMT_CPP_LIB_FILESYSTEM
+
 template <typename Char, typename PathChar>
 auto get_path_string(const std::filesystem::path& p,
                      const std::basic_string<PathChar>& native) {
@@ -111,154 +110,9 @@ void write_escaped_path(basic_memory_buffer<Char>& quoted,
   }
 }
 
-}  // namespace detail
-
-template <typename Char> struct formatter<std::filesystem::path, Char> {
- private:
-  format_specs specs_;
-  detail::arg_ref<Char> width_ref_;
-  bool debug_ = false;
-  char path_type_ = 0;
-
- public:
-  FMT_CONSTEXPR void set_debug_format(bool set = true) { debug_ = set; }
-
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) {
-    auto it = ctx.begin(), end = ctx.end();
-    if (it == end) return it;
-
-    it = detail::parse_align(it, end, specs_);
-    if (it == end) return it;
-
-    Char c = *it;
-    if ((c >= '0' && c <= '9') || c == '{')
-      it = detail::parse_width(it, end, specs_, width_ref_, ctx);
-    if (it != end && *it == '?') {
-      debug_ = true;
-      ++it;
-    }
-    if (it != end && (*it == 'g')) path_type_ = detail::to_ascii(*it++);
-    return it;
-  }
-
-  template <typename FormatContext>
-  auto format(const std::filesystem::path& p, FormatContext& ctx) const {
-    auto specs = specs_;
-    auto path_string =
-        !path_type_ ? p.native()
-                    : p.generic_string<std::filesystem::path::value_type>();
-
-    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
-                                ctx);
-    if (!debug_) {
-      auto s = detail::get_path_string<Char>(p, path_string);
-      return detail::write(ctx.out(), basic_string_view<Char>(s), specs);
-    }
-    auto quoted = basic_memory_buffer<Char>();
-    detail::write_escaped_path(quoted, p, path_string);
-    return detail::write(ctx.out(),
-                         basic_string_view<Char>(quoted.data(), quoted.size()),
-                         specs);
-  }
-};
-
-class path : public std::filesystem::path {
- public:
-  auto display_string() const -> std::string {
-    const std::filesystem::path& base = *this;
-    return fmt::format(FMT_STRING("{}"), base);
-  }
-  auto system_string() const -> std::string { return string(); }
-
-  auto generic_display_string() const -> std::string {
-    const std::filesystem::path& base = *this;
-    return fmt::format(FMT_STRING("{:g}"), base);
-  }
-  auto generic_system_string() const -> std::string { return generic_string(); }
-};
-
-FMT_END_NAMESPACE
 #endif  // FMT_CPP_LIB_FILESYSTEM
 
-FMT_BEGIN_NAMESPACE
-template <std::size_t N, typename Char>
-struct formatter<std::bitset<N>, Char>
-    : nested_formatter<basic_string_view<Char>, Char> {
- private:
-  // Functor because C++11 doesn't support generic lambdas.
-  struct writer {
-    const std::bitset<N>& bs;
-
-    template <typename OutputIt>
-    FMT_CONSTEXPR auto operator()(OutputIt out) -> OutputIt {
-      for (auto pos = N; pos > 0; --pos) {
-        out = detail::write<Char>(out, bs[pos - 1] ? Char('1') : Char('0'));
-      }
-
-      return out;
-    }
-  };
-
- public:
-  template <typename FormatContext>
-  auto format(const std::bitset<N>& bs, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return this->write_padded(ctx, writer{bs});
-  }
-};
-
-template <typename Char>
-struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
-FMT_END_NAMESPACE
-
-#ifdef __cpp_lib_optional
-FMT_BEGIN_NAMESPACE
-template <typename T, typename Char>
-struct formatter<std::optional<T>, Char,
-                 std::enable_if_t<is_formattable<T, Char>::value>> {
- private:
-  formatter<T, Char> underlying_;
-  static constexpr basic_string_view<Char> optional =
-      detail::string_literal<Char, 'o', 'p', 't', 'i', 'o', 'n', 'a', 'l',
-                             '('>{};
-  static constexpr basic_string_view<Char> none =
-      detail::string_literal<Char, 'n', 'o', 'n', 'e'>{};
-
-  template <class U>
-  FMT_CONSTEXPR static auto maybe_set_debug_format(U& u, bool set)
-      -> decltype(u.set_debug_format(set)) {
-    u.set_debug_format(set);
-  }
-
-  template <class U>
-  FMT_CONSTEXPR static void maybe_set_debug_format(U&, ...) {}
-
- public:
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) {
-    maybe_set_debug_format(underlying_, true);
-    return underlying_.parse(ctx);
-  }
-
-  template <typename FormatContext>
-  auto format(const std::optional<T>& opt, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    if (!opt) return detail::write<Char>(ctx.out(), none);
-
-    auto out = ctx.out();
-    out = detail::write<Char>(out, optional);
-    ctx.advance_to(out);
-    out = underlying_.format(*opt, ctx);
-    return detail::write(out, ')');
-  }
-};
-FMT_END_NAMESPACE
-#endif  // __cpp_lib_optional
-
 #if defined(__cpp_lib_expected) || FMT_CPP_LIB_VARIANT
-
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
 template <typename Char, typename OutputIt, typename T>
 auto write_escaped_alternative(OutputIt out, const T& v) -> OutputIt {
   if constexpr (has_to_string_view<T>::value)
@@ -266,69 +120,9 @@ auto write_escaped_alternative(OutputIt out, const T& v) -> OutputIt {
   if constexpr (std::is_same_v<T, Char>) return write_escaped_char(out, v);
   return write<Char>(out, v);
 }
-
-}  // namespace detail
-
-FMT_END_NAMESPACE
-#endif
-
-#ifdef __cpp_lib_expected
-FMT_BEGIN_NAMESPACE
-
-template <typename T, typename E, typename Char>
-struct formatter<std::expected<T, E>, Char,
-                 std::enable_if_t<(std::is_void<T>::value ||
-                                   is_formattable<T, Char>::value) &&
-                                  is_formattable<E, Char>::value>> {
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
-    return ctx.begin();
-  }
-
-  template <typename FormatContext>
-  auto format(const std::expected<T, E>& value, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    auto out = ctx.out();
-
-    if (value.has_value()) {
-      out = detail::write<Char>(out, "expected(");
-      if constexpr (!std::is_void<T>::value)
-        out = detail::write_escaped_alternative<Char>(out, *value);
-    } else {
-      out = detail::write<Char>(out, "unexpected(");
-      out = detail::write_escaped_alternative<Char>(out, value.error());
-    }
-    *out++ = ')';
-    return out;
-  }
-};
-FMT_END_NAMESPACE
-#endif  // __cpp_lib_expected
-
-#ifdef __cpp_lib_source_location
-FMT_BEGIN_NAMESPACE
-template <> struct formatter<std::source_location> {
-  FMT_CONSTEXPR auto parse(parse_context<>& ctx) { return ctx.begin(); }
-
-  template <typename FormatContext>
-  auto format(const std::source_location& loc, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    auto out = ctx.out();
-    out = detail::write(out, loc.file_name());
-    out = detail::write(out, ':');
-    out = detail::write<char>(out, loc.line());
-    out = detail::write(out, ':');
-    out = detail::write<char>(out, loc.column());
-    out = detail::write(out, ": ");
-    out = detail::write(out, loc.function_name());
-    return out;
-  }
-};
-FMT_END_NAMESPACE
 #endif
 
 #if FMT_CPP_LIB_VARIANT
-FMT_BEGIN_NAMESPACE
-namespace detail {
 
 template <typename T>
 using variant_index_sequence =
@@ -350,116 +144,9 @@ template <typename T, typename C> class is_variant_formattable_ {
       decltype(check(variant_index_sequence<T>{}))::value;
 };
 
-}  // namespace detail
-
-template <typename T> struct is_variant_like {
-  static constexpr const bool value = detail::is_variant_like_<T>::value;
-};
-
-template <typename T, typename C> struct is_variant_formattable {
-  static constexpr const bool value =
-      detail::is_variant_formattable_<T, C>::value;
-};
-
-template <typename Char> struct formatter<std::monostate, Char> {
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
-    return ctx.begin();
-  }
-
-  template <typename FormatContext>
-  auto format(const std::monostate&, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    return detail::write<Char>(ctx.out(), "monostate");
-  }
-};
-
-template <typename Variant, typename Char>
-struct formatter<
-    Variant, Char,
-    std::enable_if_t<std::conjunction_v<
-        is_variant_like<Variant>, is_variant_formattable<Variant, Char>>>> {
-  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
-    return ctx.begin();
-  }
-
-  template <typename FormatContext>
-  auto format(const Variant& value, FormatContext& ctx) const
-      -> decltype(ctx.out()) {
-    auto out = ctx.out();
-
-    out = detail::write<Char>(out, "variant(");
-    FMT_TRY {
-      std::visit(
-          [&](const auto& v) {
-            out = detail::write_escaped_alternative<Char>(out, v);
-          },
-          value);
-    }
-    FMT_CATCH(const std::bad_variant_access&) {
-      detail::write<Char>(out, "valueless by exception");
-    }
-    *out++ = ')';
-    return out;
-  }
-};
-FMT_END_NAMESPACE
 #endif  // FMT_CPP_LIB_VARIANT
 
-FMT_BEGIN_NAMESPACE
-template <> struct formatter<std::error_code> {
- private:
-  format_specs specs_;
-  detail::arg_ref<char> width_ref_;
-  bool debug_ = false;
-
- public:
-  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
-    auto it = ctx.begin(), end = ctx.end();
-    if (it == end) return it;
-
-    it = detail::parse_align(it, end, specs_);
-
-    char c = *it;
-    if (it != end && ((c >= '0' && c <= '9') || c == '{'))
-      it = detail::parse_width(it, end, specs_, width_ref_, ctx);
-
-    if (it != end && *it == '?') {
-      debug_ = true;
-      ++it;
-    }
-    if (it != end && *it == 's') {
-      specs_.set_type(presentation_type::string);
-      ++it;
-    }
-    return it;
-  }
-
-  template <typename FormatContext>
-  FMT_CONSTEXPR20 auto format(const std::error_code& ec,
-                              FormatContext& ctx) const -> decltype(ctx.out()) {
-    auto specs = specs_;
-    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
-                                ctx);
-    auto buf = memory_buffer();
-    if (specs_.type() == presentation_type::string) {
-      buf.append(ec.message());
-    } else {
-      buf.append(string_view(ec.category().name()));
-      buf.push_back(':');
-      detail::write<char>(appender(buf), ec.value());
-    }
-    auto quoted = memory_buffer();
-    auto str = string_view(buf.data(), buf.size());
-    if (debug_) {
-      detail::write_escaped_string<char>(std::back_inserter(quoted), str);
-      str = string_view(quoted.data(), quoted.size());
-    }
-    return detail::write<char>(ctx.out(), str, specs);
-  }
-};
-
 #if FMT_USE_RTTI
-namespace detail {
 
 template <typename Char, typename OutputIt>
 auto write_demangled_name(OutputIt out, const std::type_info& ti) -> OutputIt {
@@ -527,8 +214,327 @@ auto write_demangled_name(OutputIt out, const std::type_info& ti) -> OutputIt {
 #  endif
 }
 
+#endif  // FMT_USE_RTTI
+
+template <typename T, typename Enable = void>
+struct has_flip : std::false_type {};
+
+template <typename T>
+struct has_flip<T, void_t<decltype(std::declval<T>().flip())>>
+    : std::true_type {};
+
+template <typename T> struct is_bit_reference_like {
+  static constexpr const bool value =
+      std::is_convertible<T, bool>::value &&
+      std::is_nothrow_assignable<T, bool>::value && has_flip<T>::value;
+};
+
+// Workaround for libc++ incompatibility with C++ standard.
+// According to the Standard, `bitset::operator[] const` returns bool.
+#ifdef _LIBCPP_VERSION
+template <typename C>
+struct is_bit_reference_like<std::__bit_const_reference<C>> {
+  static constexpr const bool value = true;
+};
+#endif
+
 }  // namespace detail
 
+#if FMT_CPP_LIB_FILESYSTEM
+
+template <typename Char> struct formatter<std::filesystem::path, Char> {
+ private:
+  format_specs specs_;
+  detail::arg_ref<Char> width_ref_;
+  bool debug_ = false;
+  char path_type_ = 0;
+
+ public:
+  FMT_CONSTEXPR void set_debug_format(bool set = true) { debug_ = set; }
+
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) {
+    auto it = ctx.begin(), end = ctx.end();
+    if (it == end) return it;
+
+    it = detail::parse_align(it, end, specs_);
+    if (it == end) return it;
+
+    Char c = *it;
+    if ((c >= '0' && c <= '9') || c == '{')
+      it = detail::parse_width(it, end, specs_, width_ref_, ctx);
+    if (it != end && *it == '?') {
+      debug_ = true;
+      ++it;
+    }
+    if (it != end && (*it == 'g')) path_type_ = detail::to_ascii(*it++);
+    return it;
+  }
+
+  template <typename FormatContext>
+  auto format(const std::filesystem::path& p, FormatContext& ctx) const {
+    auto specs = specs_;
+    auto path_string =
+        !path_type_ ? p.native()
+                    : p.generic_string<std::filesystem::path::value_type>();
+
+    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
+                                ctx);
+    if (!debug_) {
+      auto s = detail::get_path_string<Char>(p, path_string);
+      return detail::write(ctx.out(), basic_string_view<Char>(s), specs);
+    }
+    auto quoted = basic_memory_buffer<Char>();
+    detail::write_escaped_path(quoted, p, path_string);
+    return detail::write(ctx.out(),
+                         basic_string_view<Char>(quoted.data(), quoted.size()),
+                         specs);
+  }
+};
+
+class path : public std::filesystem::path {
+ public:
+  auto display_string() const -> std::string {
+    const std::filesystem::path& base = *this;
+    return fmt::format(FMT_STRING("{}"), base);
+  }
+  auto system_string() const -> std::string { return string(); }
+
+  auto generic_display_string() const -> std::string {
+    const std::filesystem::path& base = *this;
+    return fmt::format(FMT_STRING("{:g}"), base);
+  }
+  auto generic_system_string() const -> std::string { return generic_string(); }
+};
+
+#endif  // FMT_CPP_LIB_FILESYSTEM
+
+template <std::size_t N, typename Char>
+struct formatter<std::bitset<N>, Char>
+    : nested_formatter<basic_string_view<Char>, Char> {
+ private:
+  // Functor because C++11 doesn't support generic lambdas.
+  struct writer {
+    const std::bitset<N>& bs;
+
+    template <typename OutputIt>
+    FMT_CONSTEXPR auto operator()(OutputIt out) -> OutputIt {
+      for (auto pos = N; pos > 0; --pos) {
+        out = detail::write<Char>(out, bs[pos - 1] ? Char('1') : Char('0'));
+      }
+
+      return out;
+    }
+  };
+
+ public:
+  template <typename FormatContext>
+  auto format(const std::bitset<N>& bs, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    return this->write_padded(ctx, writer{bs});
+  }
+};
+
+template <typename Char>
+struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
+
+#ifdef __cpp_lib_optional
+template <typename T, typename Char>
+struct formatter<std::optional<T>, Char,
+                 std::enable_if_t<is_formattable<T, Char>::value>> {
+ private:
+  formatter<T, Char> underlying_;
+  static constexpr basic_string_view<Char> optional =
+      detail::string_literal<Char, 'o', 'p', 't', 'i', 'o', 'n', 'a', 'l',
+                             '('>{};
+  static constexpr basic_string_view<Char> none =
+      detail::string_literal<Char, 'n', 'o', 'n', 'e'>{};
+
+  template <class U>
+  FMT_CONSTEXPR static auto maybe_set_debug_format(U& u, bool set)
+      -> decltype(u.set_debug_format(set)) {
+    u.set_debug_format(set);
+  }
+
+  template <class U>
+  FMT_CONSTEXPR static void maybe_set_debug_format(U&, ...) {}
+
+ public:
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) {
+    maybe_set_debug_format(underlying_, true);
+    return underlying_.parse(ctx);
+  }
+
+  template <typename FormatContext>
+  auto format(const std::optional<T>& opt, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    if (!opt) return detail::write<Char>(ctx.out(), none);
+
+    auto out = ctx.out();
+    out = detail::write<Char>(out, optional);
+    ctx.advance_to(out);
+    out = underlying_.format(*opt, ctx);
+    return detail::write(out, ')');
+  }
+};
+#endif  // __cpp_lib_optional
+
+#ifdef __cpp_lib_expected
+template <typename T, typename E, typename Char>
+struct formatter<std::expected<T, E>, Char,
+                 std::enable_if_t<(std::is_void<T>::value ||
+                                   is_formattable<T, Char>::value) &&
+                                  is_formattable<E, Char>::value>> {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+    return ctx.begin();
+  }
+
+  template <typename FormatContext>
+  auto format(const std::expected<T, E>& value, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    auto out = ctx.out();
+
+    if (value.has_value()) {
+      out = detail::write<Char>(out, "expected(");
+      if constexpr (!std::is_void<T>::value)
+        out = detail::write_escaped_alternative<Char>(out, *value);
+    } else {
+      out = detail::write<Char>(out, "unexpected(");
+      out = detail::write_escaped_alternative<Char>(out, value.error());
+    }
+    *out++ = ')';
+    return out;
+  }
+};
+#endif  // __cpp_lib_expected
+
+#ifdef __cpp_lib_source_location
+template <> struct formatter<std::source_location> {
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) { return ctx.begin(); }
+
+  template <typename FormatContext>
+  auto format(const std::source_location& loc, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    auto out = ctx.out();
+    out = detail::write(out, loc.file_name());
+    out = detail::write(out, ':');
+    out = detail::write<char>(out, loc.line());
+    out = detail::write(out, ':');
+    out = detail::write<char>(out, loc.column());
+    out = detail::write(out, ": ");
+    out = detail::write(out, loc.function_name());
+    return out;
+  }
+};
+#endif
+
+#if FMT_CPP_LIB_VARIANT
+
+template <typename T> struct is_variant_like {
+  static constexpr const bool value = detail::is_variant_like_<T>::value;
+};
+
+template <typename T, typename C> struct is_variant_formattable {
+  static constexpr const bool value =
+      detail::is_variant_formattable_<T, C>::value;
+};
+
+template <typename Char> struct formatter<std::monostate, Char> {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+    return ctx.begin();
+  }
+
+  template <typename FormatContext>
+  auto format(const std::monostate&, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    return detail::write<Char>(ctx.out(), "monostate");
+  }
+};
+
+template <typename Variant, typename Char>
+struct formatter<
+    Variant, Char,
+    std::enable_if_t<std::conjunction_v<
+        is_variant_like<Variant>, is_variant_formattable<Variant, Char>>>> {
+  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+    return ctx.begin();
+  }
+
+  template <typename FormatContext>
+  auto format(const Variant& value, FormatContext& ctx) const
+      -> decltype(ctx.out()) {
+    auto out = ctx.out();
+
+    out = detail::write<Char>(out, "variant(");
+    FMT_TRY {
+      std::visit(
+          [&](const auto& v) {
+            out = detail::write_escaped_alternative<Char>(out, v);
+          },
+          value);
+    }
+    FMT_CATCH(const std::bad_variant_access&) {
+      detail::write<Char>(out, "valueless by exception");
+    }
+    *out++ = ')';
+    return out;
+  }
+};
+
+#endif  // FMT_CPP_LIB_VARIANT
+
+template <> struct formatter<std::error_code> {
+ private:
+  format_specs specs_;
+  detail::arg_ref<char> width_ref_;
+  bool debug_ = false;
+
+ public:
+  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
+    auto it = ctx.begin(), end = ctx.end();
+    if (it == end) return it;
+
+    it = detail::parse_align(it, end, specs_);
+
+    char c = *it;
+    if (it != end && ((c >= '0' && c <= '9') || c == '{'))
+      it = detail::parse_width(it, end, specs_, width_ref_, ctx);
+
+    if (it != end && *it == '?') {
+      debug_ = true;
+      ++it;
+    }
+    if (it != end && *it == 's') {
+      specs_.set_type(presentation_type::string);
+      ++it;
+    }
+    return it;
+  }
+
+  template <typename FormatContext>
+  FMT_CONSTEXPR20 auto format(const std::error_code& ec,
+                              FormatContext& ctx) const -> decltype(ctx.out()) {
+    auto specs = specs_;
+    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
+                                ctx);
+    auto buf = memory_buffer();
+    if (specs_.type() == presentation_type::string) {
+      buf.append(ec.message());
+    } else {
+      buf.append(string_view(ec.category().name()));
+      buf.push_back(':');
+      detail::write<char>(appender(buf), ec.value());
+    }
+    auto quoted = memory_buffer();
+    auto str = string_view(buf.data(), buf.size());
+    if (debug_) {
+      detail::write_escaped_string<char>(std::back_inserter(quoted), str);
+      str = string_view(quoted.data(), quoted.size());
+    }
+    return detail::write<char>(ctx.out(), str, specs);
+  }
+};
+
+#if FMT_USE_RTTI
 template <typename Char>
 struct formatter<std::type_info, Char  // DEPRECATED! Mixing code unit types.
                  > {
@@ -543,7 +549,7 @@ struct formatter<std::type_info, Char  // DEPRECATED! Mixing code unit types.
     return detail::write_demangled_name<Char>(ctx.out(), ti);
   }
 };
-#endif
+#endif  // FMT_USE_RTTI
 
 template <typename T, typename Char>
 struct formatter<
@@ -579,34 +585,6 @@ struct formatter<
   }
 };
 
-namespace detail {
-
-template <typename T, typename Enable = void>
-struct has_flip : std::false_type {};
-
-template <typename T>
-struct has_flip<T, void_t<decltype(std::declval<T>().flip())>>
-    : std::true_type {};
-
-template <typename T> struct is_bit_reference_like {
-  static constexpr const bool value =
-      std::is_convertible<T, bool>::value &&
-      std::is_nothrow_assignable<T, bool>::value && has_flip<T>::value;
-};
-
-#ifdef _LIBCPP_VERSION
-
-// Workaround for libc++ incompatibility with C++ standard.
-// According to the Standard, `bitset::operator[] const` returns bool.
-template <typename C>
-struct is_bit_reference_like<std::__bit_const_reference<C>> {
-  static constexpr const bool value = true;
-};
-
-#endif
-
-}  // namespace detail
-
 // We can't use std::vector<bool, Allocator>::reference and
 // std::bitset<N>::reference because the compiler can't deduce Allocator and N
 // in partial specialization.
@@ -725,4 +703,5 @@ struct formatter<std::reference_wrapper<T>, Char,
 };
 
 FMT_END_NAMESPACE
+
 #endif  // FMT_STD_H_