Reorganize third-party dependencies into `thirdparty` directory (#491)

* rename `include` to `thirdparty`
* remove duplicate minhook in wsock32
* move minhook into its own directory
* move openssl lib into separate directories

1 files changed, 2122 insertions, 0 deletions

diff --git a/thirdparty/spdlog/fmt/bundled/core.h b/thirdparty/spdlog/fmt/bundled/core.h
new file mode 100644
index 00000000..0a81e0cc
--- /dev/null
+++ b/thirdparty/spdlog/fmt/bundled/core.h
@@ -0,0 +1,2122 @@
+// Formatting library for C++ - the core API
+//
+// Copyright (c) 2012 - present, Victor Zverovich
+// All rights reserved.
+//
+// For the license information refer to format.h.
+
+#ifndef FMT_CORE_H_
+#define FMT_CORE_H_
+
+#include <cstdio>  // std::FILE
+#include <cstring>
+#include <functional>
+#include <iterator>
+#include <memory>
+#include <string>
+#include <type_traits>
+#include <vector>
+
+// The fmt library version in the form major * 10000 + minor * 100 + patch.
+#define FMT_VERSION 70103
+
+#ifdef __clang__
+#  define FMT_CLANG_VERSION (__clang_major__ * 100 + __clang_minor__)
+#else
+#  define FMT_CLANG_VERSION 0
+#endif
+
+#if defined(__GNUC__) && !defined(__clang__)
+#  define FMT_GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
+#else
+#  define FMT_GCC_VERSION 0
+#endif
+
+#if defined(__INTEL_COMPILER)
+#  define FMT_ICC_VERSION __INTEL_COMPILER
+#else
+#  define FMT_ICC_VERSION 0
+#endif
+
+#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__)
+#  define FMT_HAS_GXX_CXX11 FMT_GCC_VERSION
+#else
+#  define FMT_HAS_GXX_CXX11 0
+#endif
+
+#ifdef __NVCC__
+#  define FMT_NVCC __NVCC__
+#else
+#  define FMT_NVCC 0
+#endif
+
+#ifdef _MSC_VER
+#  define FMT_MSC_VER _MSC_VER
+#  define FMT_SUPPRESS_MSC_WARNING(n) __pragma(warning(suppress : n))
+#else
+#  define FMT_MSC_VER 0
+#  define FMT_SUPPRESS_MSC_WARNING(n)
+#endif
+
+#ifdef __has_feature
+#  define FMT_HAS_FEATURE(x) __has_feature(x)
+#else
+#  define FMT_HAS_FEATURE(x) 0
+#endif
+
+#if defined(__has_include) && !defined(__INTELLISENSE__) && \
+    (!FMT_ICC_VERSION || FMT_ICC_VERSION >= 1600)
+#  define FMT_HAS_INCLUDE(x) __has_include(x)
+#else
+#  define FMT_HAS_INCLUDE(x) 0
+#endif
+
+#ifdef __has_cpp_attribute
+#  define FMT_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
+#else
+#  define FMT_HAS_CPP_ATTRIBUTE(x) 0
+#endif
+
+#define FMT_HAS_CPP14_ATTRIBUTE(attribute) \
+  (__cplusplus >= 201402L && FMT_HAS_CPP_ATTRIBUTE(attribute))
+
+#define FMT_HAS_CPP17_ATTRIBUTE(attribute) \
+  (__cplusplus >= 201703L && FMT_HAS_CPP_ATTRIBUTE(attribute))
+
+// Check if relaxed C++14 constexpr is supported.
+// GCC doesn't allow throw in constexpr until version 6 (bug 67371).
+#ifndef FMT_USE_CONSTEXPR
+#  define FMT_USE_CONSTEXPR                                           \
+    (FMT_HAS_FEATURE(cxx_relaxed_constexpr) || FMT_MSC_VER >= 1910 || \
+     (FMT_GCC_VERSION >= 600 && __cplusplus >= 201402L)) &&           \
+        !FMT_NVCC && !FMT_ICC_VERSION
+#endif
+#if FMT_USE_CONSTEXPR
+#  define FMT_CONSTEXPR constexpr
+#  define FMT_CONSTEXPR_DECL constexpr
+#else
+#  define FMT_CONSTEXPR inline
+#  define FMT_CONSTEXPR_DECL
+#endif
+
+#ifndef FMT_OVERRIDE
+#  if FMT_HAS_FEATURE(cxx_override_control) || \
+      (FMT_GCC_VERSION >= 408 && FMT_HAS_GXX_CXX11) || FMT_MSC_VER >= 1900
+#    define FMT_OVERRIDE override
+#  else
+#    define FMT_OVERRIDE
+#  endif
+#endif
+
+// Check if exceptions are disabled.
+#ifndef FMT_EXCEPTIONS
+#  if (defined(__GNUC__) && !defined(__EXCEPTIONS)) || \
+      FMT_MSC_VER && !_HAS_EXCEPTIONS
+#    define FMT_EXCEPTIONS 0
+#  else
+#    define FMT_EXCEPTIONS 1
+#  endif
+#endif
+
+// Define FMT_USE_NOEXCEPT to make fmt use noexcept (C++11 feature).
+#ifndef FMT_USE_NOEXCEPT
+#  define FMT_USE_NOEXCEPT 0
+#endif
+
+#if FMT_USE_NOEXCEPT || FMT_HAS_FEATURE(cxx_noexcept) || \
+    (FMT_GCC_VERSION >= 408 && FMT_HAS_GXX_CXX11) || FMT_MSC_VER >= 1900
+#  define FMT_DETECTED_NOEXCEPT noexcept
+#  define FMT_HAS_CXX11_NOEXCEPT 1
+#else
+#  define FMT_DETECTED_NOEXCEPT throw()
+#  define FMT_HAS_CXX11_NOEXCEPT 0
+#endif
+
+#ifndef FMT_NOEXCEPT
+#  if FMT_EXCEPTIONS || FMT_HAS_CXX11_NOEXCEPT
+#    define FMT_NOEXCEPT FMT_DETECTED_NOEXCEPT
+#  else
+#    define FMT_NOEXCEPT
+#  endif
+#endif
+
+// [[noreturn]] is disabled on MSVC and NVCC because of bogus unreachable code
+// warnings.
+#if FMT_EXCEPTIONS && FMT_HAS_CPP_ATTRIBUTE(noreturn) && !FMT_MSC_VER && \
+    !FMT_NVCC
+#  define FMT_NORETURN [[noreturn]]
+#else
+#  define FMT_NORETURN
+#endif
+
+#ifndef FMT_DEPRECATED
+#  if FMT_HAS_CPP14_ATTRIBUTE(deprecated) || FMT_MSC_VER >= 1900
+#    define FMT_DEPRECATED [[deprecated]]
+#  else
+#    if (defined(__GNUC__) && !defined(__LCC__)) || defined(__clang__)
+#      define FMT_DEPRECATED __attribute__((deprecated))
+#    elif FMT_MSC_VER
+#      define FMT_DEPRECATED __declspec(deprecated)
+#    else
+#      define FMT_DEPRECATED /* deprecated */
+#    endif
+#  endif
+#endif
+
+// Workaround broken [[deprecated]] in the Intel, PGI and NVCC compilers.
+#if FMT_ICC_VERSION || defined(__PGI) || FMT_NVCC
+#  define FMT_DEPRECATED_ALIAS
+#else
+#  define FMT_DEPRECATED_ALIAS FMT_DEPRECATED
+#endif
+
+#ifndef FMT_INLINE
+#  if FMT_GCC_VERSION || FMT_CLANG_VERSION
+#    define FMT_INLINE inline __attribute__((always_inline))
+#  else
+#    define FMT_INLINE inline
+#  endif
+#endif
+
+#ifndef FMT_USE_INLINE_NAMESPACES
+#  if FMT_HAS_FEATURE(cxx_inline_namespaces) || FMT_GCC_VERSION >= 404 || \
+      (FMT_MSC_VER >= 1900 && !_MANAGED)
+#    define FMT_USE_INLINE_NAMESPACES 1
+#  else
+#    define FMT_USE_INLINE_NAMESPACES 0
+#  endif
+#endif
+
+#ifndef FMT_BEGIN_NAMESPACE
+#  if FMT_USE_INLINE_NAMESPACES
+#    define FMT_INLINE_NAMESPACE inline namespace
+#    define FMT_END_NAMESPACE \
+      }                       \
+      }
+#  else
+#    define FMT_INLINE_NAMESPACE namespace
+#    define FMT_END_NAMESPACE \
+      }                       \
+      using namespace v7;     \
+      }
+#  endif
+#  define FMT_BEGIN_NAMESPACE \
+    namespace fmt {           \
+    FMT_INLINE_NAMESPACE v7 {
+#endif
+
+#if !defined(FMT_HEADER_ONLY) && defined(_WIN32)
+#  define FMT_CLASS_API FMT_SUPPRESS_MSC_WARNING(4275)
+#  ifdef FMT_EXPORT
+#    define FMT_API __declspec(dllexport)
+#    define FMT_EXTERN_TEMPLATE_API FMT_API
+#    define FMT_EXPORTED
+#  elif defined(FMT_SHARED)
+#    define FMT_API __declspec(dllimport)
+#    define FMT_EXTERN_TEMPLATE_API FMT_API
+#  endif
+#else
+#  define FMT_CLASS_API
+#endif
+#ifndef FMT_API
+#  define FMT_API
+#endif
+#ifndef FMT_EXTERN_TEMPLATE_API
+#  define FMT_EXTERN_TEMPLATE_API
+#endif
+#ifndef FMT_INSTANTIATION_DEF_API
+#  define FMT_INSTANTIATION_DEF_API FMT_API
+#endif
+
+#ifndef FMT_HEADER_ONLY
+#  define FMT_EXTERN extern
+#else
+#  define FMT_EXTERN
+#endif
+
+// libc++ supports string_view in pre-c++17.
+#if (FMT_HAS_INCLUDE(<string_view>) &&                       \
+     (__cplusplus > 201402L || defined(_LIBCPP_VERSION))) || \
+    (defined(_MSVC_LANG) && _MSVC_LANG > 201402L && _MSC_VER >= 1910)
+#  include <string_view>
+#  define FMT_USE_STRING_VIEW
+#elif FMT_HAS_INCLUDE("experimental/string_view") && __cplusplus >= 201402L
+#  include <experimental/string_view>
+#  define FMT_USE_EXPERIMENTAL_STRING_VIEW
+#endif
+
+#ifndef FMT_UNICODE
+#  define FMT_UNICODE !FMT_MSC_VER
+#endif
+#if FMT_UNICODE && FMT_MSC_VER
+#  pragma execution_character_set("utf-8")
+#endif
+
+FMT_BEGIN_NAMESPACE
+
+// Implementations of enable_if_t and other metafunctions for older systems.
+template <bool B, class T = void>
+using enable_if_t = typename std::enable_if<B, T>::type;
+template <bool B, class T, class F>
+using conditional_t = typename std::conditional<B, T, F>::type;
+template <bool B> using bool_constant = std::integral_constant<bool, B>;
+template <typename T>
+using remove_reference_t = typename std::remove_reference<T>::type;
+template <typename T>
+using remove_const_t = typename std::remove_const<T>::type;
+template <typename T>
+using remove_cvref_t = typename std::remove_cv<remove_reference_t<T>>::type;
+template <typename T> struct type_identity { using type = T; };
+template <typename T> using type_identity_t = typename type_identity<T>::type;
+
+struct monostate {};
+
+// An enable_if helper to be used in template parameters which results in much
+// shorter symbols: https://godbolt.org/z/sWw4vP. Extra parentheses are needed
+// to workaround a bug in MSVC 2019 (see #1140 and #1186).
+#define FMT_ENABLE_IF(...) enable_if_t<(__VA_ARGS__), int> = 0
+
+namespace detail {
+
+// A helper function to suppress "conditional expression is constant" warnings.
+template <typename T> constexpr T const_check(T value) { return value; }
+
+FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
+                                      const char* message);
+
+#ifndef FMT_ASSERT
+#  ifdef NDEBUG
+// FMT_ASSERT is not empty to avoid -Werror=empty-body.
+#    define FMT_ASSERT(condition, message) ((void)0)
+#  else
+#    define FMT_ASSERT(condition, message)                                    \
+      ((condition) /* void() fails with -Winvalid-constexpr on clang 4.0.1 */ \
+           ? (void)0                                                          \
+           : ::fmt::detail::assert_fail(__FILE__, __LINE__, (message)))
+#  endif
+#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)
+template <typename Char>
+using std_string_view = std::experimental::basic_string_view<Char>;
+#else
+template <typename T> struct std_string_view {};
+#endif
+
+#ifdef FMT_USE_INT128
+// Do nothing.
+#elif defined(__SIZEOF_INT128__) && !FMT_NVCC && \
+    !(FMT_CLANG_VERSION && FMT_MSC_VER)
+#  define FMT_USE_INT128 1
+using int128_t = __int128_t;
+using uint128_t = __uint128_t;
+#else
+#  define FMT_USE_INT128 0
+#endif
+#if !FMT_USE_INT128
+struct int128_t {};
+struct uint128_t {};
+#endif
+
+// Casts a nonnegative integer to unsigned.
+template <typename Int>
+FMT_CONSTEXPR typename std::make_unsigned<Int>::type to_unsigned(Int value) {
+  FMT_ASSERT(value >= 0, "negative value");
+  return static_cast<typename std::make_unsigned<Int>::type>(value);
+}
+
+FMT_SUPPRESS_MSC_WARNING(4566) constexpr unsigned char micro[] = "\u00B5";
+
+template <typename Char> constexpr bool is_unicode() {
+  return FMT_UNICODE || sizeof(Char) != 1 ||
+         (sizeof(micro) == 3 && micro[0] == 0xC2 && micro[1] == 0xB5);
+}
+
+#ifdef __cpp_char8_t
+using char8_type = char8_t;
+#else
+enum char8_type : unsigned char {};
+#endif
+}  // namespace detail
+
+#ifdef FMT_USE_INTERNAL
+namespace internal = detail;  // DEPRECATED
+#endif
+
+/**
+  An implementation of ``std::basic_string_view`` for pre-C++17. It provides a
+  subset of the API. ``fmt::basic_string_view`` is used for format strings even
+  if ``std::string_view`` is available to prevent issues when a library is
+  compiled with a different ``-std`` option than the client code (which is not
+  recommended).
+ */
+template <typename Char> class basic_string_view {
+ private:
+  const Char* data_;
+  size_t size_;
+
+ public:
+  using value_type = Char;
+  using iterator = const Char*;
+
+  constexpr basic_string_view() FMT_NOEXCEPT : data_(nullptr), size_(0) {}
+
+  /** Constructs a string reference object from a C string and a size. */
+  constexpr basic_string_view(const Char* s, size_t count) FMT_NOEXCEPT
+      : data_(s),
+        size_(count) {}
+
+  /**
+    \rst
+    Constructs a string reference object from a C string computing
+    the size with ``std::char_traits<Char>::length``.
+    \endrst
+   */
+#if __cplusplus >= 201703L  // C++17's char_traits::length() is constexpr.
+  FMT_CONSTEXPR
+#endif
+  basic_string_view(const Char* s)
+      : data_(s), size_(std::char_traits<Char>::length(s)) {}
+
+  /** Constructs a string reference from a ``std::basic_string`` object. */
+  template <typename Traits, typename Alloc>
+  FMT_CONSTEXPR basic_string_view(
+      const std::basic_string<Char, Traits, Alloc>& s) FMT_NOEXCEPT
+      : data_(s.data()),
+        size_(s.size()) {}
+
+  template <typename S, FMT_ENABLE_IF(std::is_same<
+                                      S, detail::std_string_view<Char>>::value)>
+  FMT_CONSTEXPR basic_string_view(S s) FMT_NOEXCEPT : data_(s.data()),
+                                                      size_(s.size()) {}
+
+  /** Returns a pointer to the string data. */
+  constexpr const Char* data() const { return data_; }
+
+  /** Returns the string size. */
+  constexpr size_t size() const { return size_; }
+
+  constexpr iterator begin() const { return data_; }
+  constexpr iterator end() const { return data_ + size_; }
+
+  constexpr const Char& operator[](size_t pos) const { return data_[pos]; }
+
+  FMT_CONSTEXPR void remove_prefix(size_t n) {
+    data_ += n;
+    size_ -= n;
+  }
+
+  // Lexicographically compare this string reference to other.
+  int compare(basic_string_view other) const {
+    size_t str_size = size_ < other.size_ ? size_ : other.size_;
+    int result = std::char_traits<Char>::compare(data_, other.data_, str_size);
+    if (result == 0)
+      result = size_ == other.size_ ? 0 : (size_ < other.size_ ? -1 : 1);
+    return result;
+  }
+
+  friend bool operator==(basic_string_view lhs, basic_string_view rhs) {
+    return lhs.compare(rhs) == 0;
+  }
+  friend bool operator!=(basic_string_view lhs, basic_string_view rhs) {
+    return lhs.compare(rhs) != 0;
+  }
+  friend bool operator<(basic_string_view lhs, basic_string_view rhs) {
+    return lhs.compare(rhs) < 0;
+  }
+  friend bool operator<=(basic_string_view lhs, basic_string_view rhs) {
+    return lhs.compare(rhs) <= 0;
+  }
+  friend bool operator>(basic_string_view lhs, basic_string_view rhs) {
+    return lhs.compare(rhs) > 0;
+  }
+  friend bool operator>=(basic_string_view lhs, basic_string_view rhs) {
+    return lhs.compare(rhs) >= 0;
+  }
+};
+
+using string_view = basic_string_view<char>;
+using wstring_view = basic_string_view<wchar_t>;
+
+/** Specifies if ``T`` is a character type. Can be specialized by users. */
+template <typename T> struct is_char : std::false_type {};
+template <> struct is_char<char> : std::true_type {};
+template <> struct is_char<wchar_t> : std::true_type {};
+template <> struct is_char<detail::char8_type> : std::true_type {};
+template <> struct is_char<char16_t> : std::true_type {};
+template <> struct is_char<char32_t> : std::true_type {};
+
+/**
+  \rst
+  Returns a string view of `s`. In order to add custom string type support to
+  {fmt} provide an overload of `to_string_view` for it in the same namespace as
+  the type for the argument-dependent lookup to work.
+
+  **Example**::
+
+    namespace my_ns {
+    inline string_view to_string_view(const my_string& s) {
+      return {s.data(), s.length()};
+    }
+    }
+    std::string message = fmt::format(my_string("The answer is {}"), 42);
+  \endrst
+ */
+template <typename Char, FMT_ENABLE_IF(is_char<Char>::value)>
+inline basic_string_view<Char> to_string_view(const Char* s) {
+  return s;
+}
+
+template <typename Char, typename Traits, typename Alloc>
+inline basic_string_view<Char> to_string_view(
+    const std::basic_string<Char, Traits, Alloc>& s) {
+  return s;
+}
+
+template <typename Char>
+inline basic_string_view<Char> to_string_view(basic_string_view<Char> s) {
+  return s;
+}
+
+template <typename Char,
+          FMT_ENABLE_IF(!std::is_empty<detail::std_string_view<Char>>::value)>
+inline basic_string_view<Char> to_string_view(detail::std_string_view<Char> s) {
+  return s;
+}
+
+// A base class for compile-time strings. It is defined in the fmt namespace to
+// make formatting functions visible via ADL, e.g. format(FMT_STRING("{}"), 42).
+struct compile_string {};
+
+template <typename S>
+struct is_compile_string : std::is_base_of<compile_string, S> {};
+
+template <typename S, FMT_ENABLE_IF(is_compile_string<S>::value)>
+constexpr basic_string_view<typename S::char_type> to_string_view(const S& s) {
+  return s;
+}
+
+namespace detail {
+void to_string_view(...);
+using fmt::v7::to_string_view;
+
+// Specifies whether S is a string type convertible to fmt::basic_string_view.
+// It should be a constexpr function but MSVC 2017 fails to compile it in
+// enable_if and MSVC 2015 fails to compile it as an alias template.
+template <typename S>
+struct is_string : std::is_class<decltype(to_string_view(std::declval<S>()))> {
+};
+
+template <typename S, typename = void> struct char_t_impl {};
+template <typename S> struct char_t_impl<S, enable_if_t<is_string<S>::value>> {
+  using result = decltype(to_string_view(std::declval<S>()));
+  using type = typename result::value_type;
+};
+
+// Reports a compile-time error if S is not a valid format string.
+template <typename..., typename S, FMT_ENABLE_IF(!is_compile_string<S>::value)>
+FMT_INLINE void check_format_string(const S&) {
+#ifdef FMT_ENFORCE_COMPILE_STRING
+  static_assert(is_compile_string<S>::value,
+                "FMT_ENFORCE_COMPILE_STRING requires all format strings to use "
+                "FMT_STRING.");
+#endif
+}
+template <typename..., typename S, FMT_ENABLE_IF(is_compile_string<S>::value)>
+void check_format_string(S);
+
+struct error_handler {
+  constexpr error_handler() = default;
+  constexpr error_handler(const error_handler&) = default;
+
+  // This function is intentionally not constexpr to give a compile-time error.
+  FMT_NORETURN FMT_API void on_error(const char* message);
+};
+}  // namespace detail
+
+/** String's character type. */
+template <typename S> using char_t = typename detail::char_t_impl<S>::type;
+
+/**
+  \rst
+  Parsing context consisting of a format string range being parsed and an
+  argument counter for automatic indexing.
+
+  You can use one of the following type aliases for common character types:
+
+  +-----------------------+-------------------------------------+
+  | Type                  | Definition                          |
+  +=======================+=====================================+
+  | format_parse_context  | basic_format_parse_context<char>    |
+  +-----------------------+-------------------------------------+
+  | wformat_parse_context | basic_format_parse_context<wchar_t> |
+  +-----------------------+-------------------------------------+
+  \endrst
+ */
+template <typename Char, typename ErrorHandler = detail::error_handler>
+class basic_format_parse_context : private ErrorHandler {
+ private:
+  basic_string_view<Char> format_str_;
+  int next_arg_id_;
+
+ public:
+  using char_type = Char;
+  using iterator = typename basic_string_view<Char>::iterator;
+
+  explicit constexpr basic_format_parse_context(
+      basic_string_view<Char> format_str, ErrorHandler eh = {},
+      int next_arg_id = 0)
+      : ErrorHandler(eh), format_str_(format_str), next_arg_id_(next_arg_id) {}
+
+  /**
+    Returns an iterator to the beginning of the format string range being
+    parsed.
+   */
+  constexpr iterator begin() const FMT_NOEXCEPT { return format_str_.begin(); }
+
+  /**
+    Returns an iterator past the end of the format string range being parsed.
+   */
+  constexpr iterator end() const FMT_NOEXCEPT { return format_str_.end(); }
+
+  /** Advances the begin iterator to ``it``. */
+  FMT_CONSTEXPR void advance_to(iterator it) {
+    format_str_.remove_prefix(detail::to_unsigned(it - begin()));
+  }
+
+  /**
+    Reports an error if using the manual argument indexing; otherwise returns
+    the next argument index and switches to the automatic indexing.
+   */
+  FMT_CONSTEXPR int next_arg_id() {
+    // Don't check if the argument id is valid to avoid overhead and because it
+    // will be checked during formatting anyway.
+    if (next_arg_id_ >= 0) return next_arg_id_++;
+    on_error("cannot switch from manual to automatic argument indexing");
+    return 0;
+  }
+
+  /**
+    Reports an error if using the automatic argument indexing; otherwise
+    switches to the manual indexing.
+   */
+  FMT_CONSTEXPR void check_arg_id(int) {
+    if (next_arg_id_ > 0)
+      on_error("cannot switch from automatic to manual argument indexing");
+    else
+      next_arg_id_ = -1;
+  }
+
+  FMT_CONSTEXPR void check_arg_id(basic_string_view<Char>) {}
+
+  FMT_CONSTEXPR void on_error(const char* message) {
+    ErrorHandler::on_error(message);
+  }
+
+  constexpr ErrorHandler error_handler() const { return *this; }
+};
+
+using format_parse_context = basic_format_parse_context<char>;
+using wformat_parse_context = basic_format_parse_context<wchar_t>;
+
+template <typename Context> class basic_format_arg;
+template <typename Context> class basic_format_args;
+template <typename Context> class dynamic_format_arg_store;
+
+// A formatter for objects of type T.
+template <typename T, typename Char = char, typename Enable = void>
+struct formatter {
+  // A deleted default constructor indicates a disabled formatter.
+  formatter() = delete;
+};
+
+// Specifies if T has an enabled formatter specialization. A type can be
+// formattable even if it doesn't have a formatter e.g. via a conversion.
+template <typename T, typename Context>
+using has_formatter =
+    std::is_constructible<typename Context::template formatter_type<T>>;
+
+// Checks whether T is a container with contiguous storage.
+template <typename T> struct is_contiguous : std::false_type {};
+template <typename Char>
+struct is_contiguous<std::basic_string<Char>> : std::true_type {};
+
+namespace detail {
+
+// Extracts a reference to the container from back_insert_iterator.
+template <typename Container>
+inline Container& get_container(std::back_insert_iterator<Container> it) {
+  using bi_iterator = std::back_insert_iterator<Container>;
+  struct accessor : bi_iterator {
+    accessor(bi_iterator iter) : bi_iterator(iter) {}
+    using bi_iterator::container;
+  };
+  return *accessor(it).container;
+}
+
+/**
+  \rst
+  A contiguous memory buffer with an optional growing ability. It is an internal
+  class and shouldn't be used directly, only via `~fmt::basic_memory_buffer`.
+  \endrst
+ */
+template <typename T> class buffer {
+ private:
+  T* ptr_;
+  size_t size_;
+  size_t capacity_;
+
+ protected:
+  // Don't initialize ptr_ since it is not accessed to save a few cycles.
+  FMT_SUPPRESS_MSC_WARNING(26495)
+  buffer(size_t sz) FMT_NOEXCEPT : size_(sz), capacity_(sz) {}
+
+  buffer(T* p = nullptr, size_t sz = 0, size_t cap = 0) FMT_NOEXCEPT
+      : ptr_(p),
+        size_(sz),
+        capacity_(cap) {}
+
+  ~buffer() = default;
+
+  /** Sets the buffer data and capacity. */
+  void set(T* buf_data, size_t buf_capacity) FMT_NOEXCEPT {
+    ptr_ = buf_data;
+    capacity_ = buf_capacity;
+  }
+
+  /** Increases the buffer capacity to hold at least *capacity* elements. */
+  virtual void grow(size_t capacity) = 0;
+
+ public:
+  using value_type = T;
+  using const_reference = const T&;
+
+  buffer(const buffer&) = delete;
+  void operator=(const buffer&) = delete;
+
+  T* begin() FMT_NOEXCEPT { return ptr_; }
+  T* end() FMT_NOEXCEPT { return ptr_ + size_; }
+
+  const T* begin() const FMT_NOEXCEPT { return ptr_; }
+  const T* end() const FMT_NOEXCEPT { return ptr_ + size_; }
+
+  /** Returns the size of this buffer. */
+  size_t size() const FMT_NOEXCEPT { return size_; }
+
+  /** Returns the capacity of this buffer. */
+  size_t capacity() const FMT_NOEXCEPT { return capacity_; }
+
+  /** Returns a pointer to the buffer data. */
+  T* data() FMT_NOEXCEPT { return ptr_; }
+
+  /** Returns a pointer to the buffer data. */
+  const T* data() const FMT_NOEXCEPT { return ptr_; }
+
+  /** Clears this buffer. */
+  void clear() { size_ = 0; }
+
+  // Tries resizing the buffer to contain *count* elements. If T is a POD type
+  // the new elements may not be initialized.
+  void try_resize(size_t count) {
+    try_reserve(count);
+    size_ = count <= capacity_ ? count : capacity_;
+  }
+
+  // Tries increasing the buffer capacity to *new_capacity*. It can increase the
+  // capacity by a smaller amount than requested but guarantees there is space
+  // for at least one additional element either by increasing the capacity or by
+  // flushing the buffer if it is full.
+  void try_reserve(size_t new_capacity) {
+    if (new_capacity > capacity_) grow(new_capacity);
+  }
+
+  void push_back(const T& value) {
+    try_reserve(size_ + 1);
+    ptr_[size_++] = value;
+  }
+
+  /** Appends data to the end of the buffer. */
+  template <typename U> void append(const U* begin, const U* end);
+
+  template <typename I> T& operator[](I index) { return ptr_[index]; }
+  template <typename I> const T& operator[](I index) const {
+    return ptr_[index];
+  }
+};
+
+struct buffer_traits {
+  explicit buffer_traits(size_t) {}
+  size_t count() const { return 0; }
+  size_t limit(size_t size) { return size; }
+};
+
+class fixed_buffer_traits {
+ private:
+  size_t count_ = 0;
+  size_t limit_;
+
+ public:
+  explicit fixed_buffer_traits(size_t limit) : limit_(limit) {}
+  size_t count() const { return count_; }
+  size_t limit(size_t size) {
+    size_t n = limit_ > count_ ? limit_ - count_ : 0;
+    count_ += size;
+    return size < n ? size : n;
+  }
+};
+
+// A buffer that writes to an output iterator when flushed.
+template <typename OutputIt, typename T, typename Traits = buffer_traits>
+class iterator_buffer final : public Traits, public buffer<T> {
+ private:
+  OutputIt out_;
+  enum { buffer_size = 256 };
+  T data_[buffer_size];
+
+ protected:
+  void grow(size_t) final FMT_OVERRIDE {
+    if (this->size() == buffer_size) flush();
+  }
+  void flush();
+
+ public:
+  explicit iterator_buffer(OutputIt out, size_t n = buffer_size)
+      : Traits(n),
+        buffer<T>(data_, 0, buffer_size),
+        out_(out) {}
+  ~iterator_buffer() { flush(); }
+
+  OutputIt out() {
+    flush();
+    return out_;
+  }
+  size_t count() const { return Traits::count() + this->size(); }
+};
+
+template <typename T> class iterator_buffer<T*, T> final : public buffer<T> {
+ protected:
+  void grow(size_t) final FMT_OVERRIDE {}
+
+ public:
+  explicit iterator_buffer(T* out, size_t = 0) : buffer<T>(out, 0, ~size_t()) {}
+
+  T* out() { return &*this->end(); }
+};
+
+// A buffer that writes to a container with the contiguous storage.
+template <typename Container>
+class iterator_buffer<std::back_insert_iterator<Container>,
+                      enable_if_t<is_contiguous<Container>::value,
+                                  typename Container::value_type>>
+    final : public buffer<typename Container::value_type> {
+ private:
+  Container& container_;
+
+ protected:
+  void grow(size_t capacity) final FMT_OVERRIDE {
+    container_.resize(capacity);
+    this->set(&container_[0], capacity);
+  }
+
+ public:
+  explicit iterator_buffer(Container& c)
+      : buffer<typename Container::value_type>(c.size()), container_(c) {}
+  explicit iterator_buffer(std::back_insert_iterator<Container> out, size_t = 0)
+      : iterator_buffer(get_container(out)) {}
+  std::back_insert_iterator<Container> out() {
+    return std::back_inserter(container_);
+  }
+};
+
+// A buffer that counts the number of code units written discarding the output.
+template <typename T = char> class counting_buffer final : public buffer<T> {
+ private:
+  enum { buffer_size = 256 };
+  T data_[buffer_size];
+  size_t count_ = 0;
+
+ protected:
+  void grow(size_t) final FMT_OVERRIDE {
+    if (this->size() != buffer_size) return;
+    count_ += this->size();
+    this->clear();
+  }
+
+ public:
+  counting_buffer() : buffer<T>(data_, 0, buffer_size) {}
+
+  size_t count() { return count_ + this->size(); }
+};
+
+// An output iterator that appends to the buffer.
+// It is used to reduce symbol sizes for the common case.
+template <typename T>
+class buffer_appender : public std::back_insert_iterator<buffer<T>> {
+  using base = std::back_insert_iterator<buffer<T>>;
+
+ public:
+  explicit buffer_appender(buffer<T>& buf) : base(buf) {}
+  buffer_appender(base it) : base(it) {}
+
+  buffer_appender& operator++() {
+    base::operator++();
+    return *this;
+  }
+
+  buffer_appender operator++(int) {
+    buffer_appender tmp = *this;
+    ++*this;
+    return tmp;
+  }
+};
+
+// Maps an output iterator into a buffer.
+template <typename T, typename OutputIt>
+iterator_buffer<OutputIt, T> get_buffer(OutputIt);
+template <typename T> buffer<T>& get_buffer(buffer_appender<T>);
+
+template <typename OutputIt> OutputIt get_buffer_init(OutputIt out) {
+  return out;
+}
+template <typename T> buffer<T>& get_buffer_init(buffer_appender<T> out) {
+  return get_container(out);
+}
+
+template <typename Buffer>
+auto get_iterator(Buffer& buf) -> decltype(buf.out()) {
+  return buf.out();
+}
+template <typename T> buffer_appender<T> get_iterator(buffer<T>& buf) {
+  return buffer_appender<T>(buf);
+}
+
+template <typename T, typename Char = char, typename Enable = void>
+struct fallback_formatter {
+  fallback_formatter() = delete;
+};
+
+// Specifies if T has an enabled fallback_formatter specialization.
+template <typename T, typename Context>
+using has_fallback_formatter =
+    std::is_constructible<fallback_formatter<T, typename Context::char_type>>;
+
+struct view {};
+
+template <typename Char, typename T> struct named_arg : view {
+  const Char* name;
+  const T& value;
+  named_arg(const Char* n, const T& v) : name(n), value(v) {}
+};
+
+template <typename Char> struct named_arg_info {
+  const Char* name;
+  int id;
+};
+
+template <typename T, typename Char, size_t NUM_ARGS, size_t NUM_NAMED_ARGS>
+struct arg_data {
+  // args_[0].named_args points to named_args_ to avoid bloating format_args.
+  // +1 to workaround a bug in gcc 7.5 that causes duplicated-branches warning.
+  T args_[1 + (NUM_ARGS != 0 ? NUM_ARGS : +1)];
+  named_arg_info<Char> named_args_[NUM_NAMED_ARGS];
+
+  template <typename... U>
+  arg_data(const U&... init) : args_{T(named_args_, NUM_NAMED_ARGS), init...} {}
+  arg_data(const arg_data& other) = delete;
+  const T* args() const { return args_ + 1; }
+  named_arg_info<Char>* named_args() { return named_args_; }
+};
+
+template <typename T, typename Char, size_t NUM_ARGS>
+struct arg_data<T, Char, NUM_ARGS, 0> {
+  // +1 to workaround a bug in gcc 7.5 that causes duplicated-branches warning.
+  T args_[NUM_ARGS != 0 ? NUM_ARGS : +1];
+
+  template <typename... U>
+  FMT_INLINE arg_data(const U&... init) : args_{init...} {}
+  FMT_INLINE const T* args() const { return args_; }
+  FMT_INLINE std::nullptr_t named_args() { return nullptr; }
+};
+
+template <typename Char>
+inline void init_named_args(named_arg_info<Char>*, int, int) {}
+
+template <typename Char, typename T, typename... Tail>
+void init_named_args(named_arg_info<Char>* named_args, int arg_count,
+                     int named_arg_count, const T&, const Tail&... args) {
+  init_named_args(named_args, arg_count + 1, named_arg_count, args...);
+}
+
+template <typename Char, typename T, typename... Tail>
+void init_named_args(named_arg_info<Char>* named_args, int arg_count,
+                     int named_arg_count, const named_arg<Char, T>& arg,
+                     const Tail&... args) {
+  named_args[named_arg_count++] = {arg.name, arg_count};
+  init_named_args(named_args, arg_count + 1, named_arg_count, args...);
+}
+
+template <typename... Args>
+FMT_INLINE void init_named_args(std::nullptr_t, int, int, const Args&...) {}
+
+template <typename T> struct is_named_arg : std::false_type {};
+
+template <typename T, typename Char>
+struct is_named_arg<named_arg<Char, T>> : std::true_type {};
+
+template <bool B = false> constexpr size_t count() { return B ? 1 : 0; }
+template <bool B1, bool B2, bool... Tail> constexpr size_t count() {
+  return (B1 ? 1 : 0) + count<B2, Tail...>();
+}
+
+template <typename... Args> constexpr size_t count_named_args() {
+  return count<is_named_arg<Args>::value...>();
+}
+
+enum class type {
+  none_type,
+  // Integer types should go first,
+  int_type,
+  uint_type,
+  long_long_type,
+  ulong_long_type,
+  int128_type,
+  uint128_type,
+  bool_type,
+  char_type,
+  last_integer_type = char_type,
+  // followed by floating-point types.
+  float_type,
+  double_type,
+  long_double_type,
+  last_numeric_type = long_double_type,
+  cstring_type,
+  string_type,
+  pointer_type,
+  custom_type
+};
+
+// Maps core type T to the corresponding type enum constant.
+template <typename T, typename Char>
+struct type_constant : std::integral_constant<type, type::custom_type> {};
+
+#define FMT_TYPE_CONSTANT(Type, constant) \
+  template <typename Char>                \
+  struct type_constant<Type, Char>        \
+      : std::integral_constant<type, type::constant> {}
+
+FMT_TYPE_CONSTANT(int, int_type);
+FMT_TYPE_CONSTANT(unsigned, uint_type);
+FMT_TYPE_CONSTANT(long long, long_long_type);
+FMT_TYPE_CONSTANT(unsigned long long, ulong_long_type);
+FMT_TYPE_CONSTANT(int128_t, int128_type);
+FMT_TYPE_CONSTANT(uint128_t, uint128_type);
+FMT_TYPE_CONSTANT(bool, bool_type);
+FMT_TYPE_CONSTANT(Char, char_type);
+FMT_TYPE_CONSTANT(float, float_type);
+FMT_TYPE_CONSTANT(double, double_type);
+FMT_TYPE_CONSTANT(long double, long_double_type);
+FMT_TYPE_CONSTANT(const Char*, cstring_type);
+FMT_TYPE_CONSTANT(basic_string_view<Char>, string_type);
+FMT_TYPE_CONSTANT(const void*, pointer_type);
+
+constexpr bool is_integral_type(type t) {
+  return t > type::none_type && t <= type::last_integer_type;
+}
+
+constexpr bool is_arithmetic_type(type t) {
+  return t > type::none_type && t <= type::last_numeric_type;
+}
+
+template <typename Char> struct string_value {
+  const Char* data;
+  size_t size;
+};
+
+template <typename Char> struct named_arg_value {
+  const named_arg_info<Char>* data;
+  size_t size;
+};
+
+template <typename Context> struct custom_value {
+  using parse_context = typename Context::parse_context_type;
+  const void* value;
+  void (*format)(const void* arg, parse_context& parse_ctx, Context& ctx);
+};
+
+// A formatting argument value.
+template <typename Context> class value {
+ public:
+  using char_type = typename Context::char_type;
+
+  union {
+    int int_value;
+    unsigned uint_value;
+    long long long_long_value;
+    unsigned long long ulong_long_value;
+    int128_t int128_value;
+    uint128_t uint128_value;
+    bool bool_value;
+    char_type char_value;
+    float float_value;
+    double double_value;
+    long double long_double_value;
+    const void* pointer;
+    string_value<char_type> string;
+    custom_value<Context> custom;
+    named_arg_value<char_type> named_args;
+  };
+
+  constexpr FMT_INLINE value(int val = 0) : int_value(val) {}
+  constexpr FMT_INLINE value(unsigned val) : uint_value(val) {}
+  FMT_INLINE value(long long val) : long_long_value(val) {}
+  FMT_INLINE value(unsigned long long val) : ulong_long_value(val) {}
+  FMT_INLINE value(int128_t val) : int128_value(val) {}
+  FMT_INLINE value(uint128_t val) : uint128_value(val) {}
+  FMT_INLINE value(float val) : float_value(val) {}
+  FMT_INLINE value(double val) : double_value(val) {}
+  FMT_INLINE value(long double val) : long_double_value(val) {}
+  FMT_INLINE value(bool val) : bool_value(val) {}
+  FMT_INLINE value(char_type val) : char_value(val) {}
+  FMT_INLINE value(const char_type* val) { string.data = val; }
+  FMT_INLINE value(basic_string_view<char_type> val) {
+    string.data = val.data();
+    string.size = val.size();
+  }
+  FMT_INLINE value(const void* val) : pointer(val) {}
+  FMT_INLINE value(const named_arg_info<char_type>* args, size_t size)
+      : named_args{args, size} {}
+
+  template <typename T> FMT_INLINE value(const T& val) {
+    custom.value = &val;
+    // Get the formatter type through the context to allow different contexts
+    // have different extension points, e.g. `formatter<T>` for `format` and
+    // `printf_formatter<T>` for `printf`.
+    custom.format = format_custom_arg<
+        T, conditional_t<has_formatter<T, Context>::value,
+                         typename Context::template formatter_type<T>,
+                         fallback_formatter<T, char_type>>>;
+  }
+
+ private:
+  // Formats an argument of a custom type, such as a user-defined class.
+  template <typename T, typename Formatter>
+  static void format_custom_arg(const void* arg,
+                                typename Context::parse_context_type& parse_ctx,
+                                Context& ctx) {
+    Formatter f;
+    parse_ctx.advance_to(f.parse(parse_ctx));
+    ctx.advance_to(f.format(*static_cast<const T*>(arg), ctx));
+  }
+};
+
+template <typename Context, typename T>
+FMT_CONSTEXPR basic_format_arg<Context> make_arg(const T& value);
+
+// To minimize the number of types we need to deal with, long is translated
+// either to int or to long long depending on its size.
+enum { long_short = sizeof(long) == sizeof(int) };
+using long_type = conditional_t<long_short, int, long long>;
+using ulong_type = conditional_t<long_short, unsigned, unsigned long long>;
+
+struct unformattable {};
+
+// Maps formatting arguments to core types.
+template <typename Context> struct arg_mapper {
+  using char_type = typename Context::char_type;
+
+  FMT_CONSTEXPR int map(signed char val) { return val; }
+  FMT_CONSTEXPR unsigned map(unsigned char val) { return val; }
+  FMT_CONSTEXPR int map(short val) { return val; }
+  FMT_CONSTEXPR unsigned map(unsigned short val) { return val; }
+  FMT_CONSTEXPR int map(int val) { return val; }
+  FMT_CONSTEXPR unsigned map(unsigned val) { return val; }
+  FMT_CONSTEXPR long_type map(long val) { return val; }
+  FMT_CONSTEXPR ulong_type map(unsigned long val) { return val; }
+  FMT_CONSTEXPR long long map(long long val) { return val; }
+  FMT_CONSTEXPR unsigned long long map(unsigned long long val) { return val; }
+  FMT_CONSTEXPR int128_t map(int128_t val) { return val; }
+  FMT_CONSTEXPR uint128_t map(uint128_t val) { return val; }
+  FMT_CONSTEXPR bool map(bool val) { return val; }
+
+  template <typename T, FMT_ENABLE_IF(is_char<T>::value)>
+  FMT_CONSTEXPR char_type map(T val) {
+    static_assert(
+        std::is_same<T, char>::value || std::is_same<T, char_type>::value,
+        "mixing character types is disallowed");
+    return val;
+  }
+
+  FMT_CONSTEXPR float map(float val) { return val; }
+  FMT_CONSTEXPR double map(double val) { return val; }
+  FMT_CONSTEXPR long double map(long double val) { return val; }
+
+  FMT_CONSTEXPR const char_type* map(char_type* val) { return val; }
+  FMT_CONSTEXPR const char_type* map(const char_type* val) { return val; }
+  template <typename T, FMT_ENABLE_IF(is_string<T>::value)>
+  FMT_CONSTEXPR basic_string_view<char_type> map(const T& val) {
+    static_assert(std::is_same<char_type, char_t<T>>::value,
+                  "mixing character types is disallowed");
+    return to_string_view(val);
+  }
+  template <typename T,
+            FMT_ENABLE_IF(
+                std::is_constructible<basic_string_view<char_type>, T>::value &&
+                !is_string<T>::value && !has_formatter<T, Context>::value &&
+                !has_fallback_formatter<T, Context>::value)>
+  FMT_CONSTEXPR basic_string_view<char_type> map(const T& val) {
+    return basic_string_view<char_type>(val);
+  }
+  template <
+      typename T,
+      FMT_ENABLE_IF(
+          std::is_constructible<std_string_view<char_type>, T>::value &&
+          !std::is_constructible<basic_string_view<char_type>, T>::value &&
+          !is_string<T>::value && !has_formatter<T, Context>::value &&
+          !has_fallback_formatter<T, Context>::value)>
+  FMT_CONSTEXPR basic_string_view<char_type> map(const T& val) {
+    return std_string_view<char_type>(val);
+  }
+  FMT_CONSTEXPR const char* map(const signed char* val) {
+    static_assert(std::is_same<char_type, char>::value, "invalid string type");
+    return reinterpret_cast<const char*>(val);
+  }
+  FMT_CONSTEXPR const char* map(const unsigned char* val) {
+    static_assert(std::is_same<char_type, char>::value, "invalid string type");
+    return reinterpret_cast<const char*>(val);
+  }
+  FMT_CONSTEXPR const char* map(signed char* val) {
+    const auto* const_val = val;
+    return map(const_val);
+  }
+  FMT_CONSTEXPR const char* map(unsigned char* val) {
+    const auto* const_val = val;
+    return map(const_val);
+  }
+
+  FMT_CONSTEXPR const void* map(void* val) { return val; }
+  FMT_CONSTEXPR const void* map(const void* val) { return val; }
+  FMT_CONSTEXPR const void* map(std::nullptr_t val) { return val; }
+  template <typename T> FMT_CONSTEXPR int map(const T*) {
+    // Formatting of arbitrary pointers is disallowed. If you want to output
+    // a pointer cast it to "void *" or "const void *". In particular, this
+    // forbids formatting of "[const] volatile char *" which is printed as bool
+    // by iostreams.
+    static_assert(!sizeof(T), "formatting of non-void pointers is disallowed");
+    return 0;
+  }
+
+  template <typename T,
+            FMT_ENABLE_IF(std::is_enum<T>::value &&
+                          !has_formatter<T, Context>::value &&
+                          !has_fallback_formatter<T, Context>::value)>
+  FMT_CONSTEXPR auto map(const T& val)
+      -> decltype(std::declval<arg_mapper>().map(
+          static_cast<typename std::underlying_type<T>::type>(val))) {
+    return map(static_cast<typename std::underlying_type<T>::type>(val));
+  }
+  template <typename T,
+            FMT_ENABLE_IF(!is_string<T>::value && !is_char<T>::value &&
+                          (has_formatter<T, Context>::value ||
+                           has_fallback_formatter<T, Context>::value))>
+  FMT_CONSTEXPR const T& map(const T& val) {
+    return val;
+  }
+
+  template <typename T>
+  FMT_CONSTEXPR auto map(const named_arg<char_type, T>& val)
+      -> decltype(std::declval<arg_mapper>().map(val.value)) {
+    return map(val.value);
+  }
+
+  unformattable map(...) { return {}; }
+};
+
+// A type constant after applying arg_mapper<Context>.
+template <typename T, typename Context>
+using mapped_type_constant =
+    type_constant<decltype(arg_mapper<Context>().map(std::declval<const T&>())),
+                  typename Context::char_type>;
+
+enum { packed_arg_bits = 4 };
+// Maximum number of arguments with packed types.
+enum { max_packed_args = 62 / packed_arg_bits };
+enum : unsigned long long { is_unpacked_bit = 1ULL << 63 };
+enum : unsigned long long { has_named_args_bit = 1ULL << 62 };
+}  // namespace detail
+
+// A formatting argument. It is a trivially copyable/constructible type to
+// allow storage in basic_memory_buffer.
+template <typename Context> class basic_format_arg {
+ private:
+  detail::value<Context> value_;
+  detail::type type_;
+
+  template <typename ContextType, typename T>
+  friend FMT_CONSTEXPR basic_format_arg<ContextType> detail::make_arg(
+      const T& value);
+
+  template <typename Visitor, typename Ctx>
+  friend FMT_CONSTEXPR auto visit_format_arg(Visitor&& vis,
+                                             const basic_format_arg<Ctx>& arg)
+      -> decltype(vis(0));
+
+  friend class basic_format_args<Context>;
+  friend class dynamic_format_arg_store<Context>;
+
+  using char_type = typename Context::char_type;
+
+  template <typename T, typename Char, size_t NUM_ARGS, size_t NUM_NAMED_ARGS>
+  friend struct detail::arg_data;
+
+  basic_format_arg(const detail::named_arg_info<char_type>* args, size_t size)
+      : value_(args, size) {}
+
+ public:
+  class handle {
+   public:
+    explicit handle(detail::custom_value<Context> custom) : custom_(custom) {}
+
+    void format(typename Context::parse_context_type& parse_ctx,
+                Context& ctx) const {
+      custom_.format(custom_.value, parse_ctx, ctx);
+    }
+
+   private:
+    detail::custom_value<Context> custom_;
+  };
+
+  constexpr basic_format_arg() : type_(detail::type::none_type) {}
+
+  constexpr explicit operator bool() const FMT_NOEXCEPT {
+    return type_ != detail::type::none_type;
+  }
+
+  detail::type type() const { return type_; }
+
+  bool is_integral() const { return detail::is_integral_type(type_); }
+  bool is_arithmetic() const { return detail::is_arithmetic_type(type_); }
+};
+
+/**
+  \rst
+  Visits an argument dispatching to the appropriate visit method based on
+  the argument type. For example, if the argument type is ``double`` then
+  ``vis(value)`` will be called with the value of type ``double``.
+  \endrst
+ */
+template <typename Visitor, typename Context>
+FMT_CONSTEXPR_DECL FMT_INLINE auto visit_format_arg(
+    Visitor&& vis, const basic_format_arg<Context>& arg) -> decltype(vis(0)) {
+  using char_type = typename Context::char_type;
+  switch (arg.type_) {
+  case detail::type::none_type:
+    break;
+  case detail::type::int_type:
+    return vis(arg.value_.int_value);
+  case detail::type::uint_type:
+    return vis(arg.value_.uint_value);
+  case detail::type::long_long_type:
+    return vis(arg.value_.long_long_value);
+  case detail::type::ulong_long_type:
+    return vis(arg.value_.ulong_long_value);
+#if FMT_USE_INT128
+  case detail::type::int128_type:
+    return vis(arg.value_.int128_value);
+  case detail::type::uint128_type:
+    return vis(arg.value_.uint128_value);
+#else
+  case detail::type::int128_type:
+  case detail::type::uint128_type:
+    break;
+#endif
+  case detail::type::bool_type:
+    return vis(arg.value_.bool_value);
+  case detail::type::char_type:
+    return vis(arg.value_.char_value);
+  case detail::type::float_type:
+    return vis(arg.value_.float_value);
+  case detail::type::double_type:
+    return vis(arg.value_.double_value);
+  case detail::type::long_double_type:
+    return vis(arg.value_.long_double_value);
+  case detail::type::cstring_type:
+    return vis(arg.value_.string.data);
+  case detail::type::string_type:
+    return vis(basic_string_view<char_type>(arg.value_.string.data,
+                                            arg.value_.string.size));
+  case detail::type::pointer_type:
+    return vis(arg.value_.pointer);
+  case detail::type::custom_type:
+    return vis(typename basic_format_arg<Context>::handle(arg.value_.custom));
+  }
+  return vis(monostate());
+}
+
+template <typename T> struct formattable : std::false_type {};
+
+namespace detail {
+
+// A workaround for gcc 4.8 to make void_t work in a SFINAE context.
+template <typename... Ts> struct void_t_impl { using type = void; };
+template <typename... Ts>
+using void_t = typename detail::void_t_impl<Ts...>::type;
+
+template <typename It, typename T, typename Enable = void>
+struct is_output_iterator : std::false_type {};
+
+template <typename It, typename T>
+struct is_output_iterator<
+    It, T,
+    void_t<typename std::iterator_traits<It>::iterator_category,
+           decltype(*std::declval<It>() = std::declval<T>())>>
+    : std::true_type {};
+
+template <typename OutputIt>
+struct is_back_insert_iterator : std::false_type {};
+template <typename Container>
+struct is_back_insert_iterator<std::back_insert_iterator<Container>>
+    : std::true_type {};
+
+template <typename OutputIt>
+struct is_contiguous_back_insert_iterator : std::false_type {};
+template <typename Container>
+struct is_contiguous_back_insert_iterator<std::back_insert_iterator<Container>>
+    : is_contiguous<Container> {};
+template <typename Char>
+struct is_contiguous_back_insert_iterator<buffer_appender<Char>>
+    : std::true_type {};
+
+// A type-erased reference to an std::locale to avoid heavy <locale> include.
+class locale_ref {
+ private:
+  const void* locale_;  // A type-erased pointer to std::locale.
+
+ public:
+  locale_ref() : locale_(nullptr) {}
+  template <typename Locale> explicit locale_ref(const Locale& loc);
+
+  explicit operator bool() const FMT_NOEXCEPT { return locale_ != nullptr; }
+
+  template <typename Locale> Locale get() const;
+};
+
+template <typename> constexpr unsigned long long encode_types() { return 0; }
+
+template <typename Context, typename Arg, typename... Args>
+constexpr unsigned long long encode_types() {
+  return static_cast<unsigned>(mapped_type_constant<Arg, Context>::value) |
+         (encode_types<Context, Args...>() << packed_arg_bits);
+}
+
+template <typename Context, typename T>
+FMT_CONSTEXPR basic_format_arg<Context> make_arg(const T& value) {
+  basic_format_arg<Context> arg;
+  arg.type_ = mapped_type_constant<T, Context>::value;
+  arg.value_ = arg_mapper<Context>().map(value);
+  return arg;
+}
+
+template <typename T> int check(unformattable) {
+  static_assert(
+      formattable<T>(),
+      "Cannot format an argument. To make type T formattable provide a "
+      "formatter<T> specialization: https://fmt.dev/latest/api.html#udt");
+  return 0;
+}
+template <typename T, typename U> inline const U& check(const U& val) {
+  return val;
+}
+
+// The type template parameter is there to avoid an ODR violation when using
+// a fallback formatter in one translation unit and an implicit conversion in
+// another (not recommended).
+template <bool IS_PACKED, typename Context, type, typename T,
+          FMT_ENABLE_IF(IS_PACKED)>
+inline value<Context> make_arg(const T& val) {
+  return check<T>(arg_mapper<Context>().map(val));
+}
+
+template <bool IS_PACKED, typename Context, type, typename T,
+          FMT_ENABLE_IF(!IS_PACKED)>
+inline basic_format_arg<Context> make_arg(const T& value) {
+  return make_arg<Context>(value);
+}
+
+template <typename T> struct is_reference_wrapper : std::false_type {};
+template <typename T>
+struct is_reference_wrapper<std::reference_wrapper<T>> : std::true_type {};
+
+template <typename T> const T& unwrap(const T& v) { return v; }
+template <typename T> const T& unwrap(const std::reference_wrapper<T>& v) {
+  return static_cast<const T&>(v);
+}
+
+class dynamic_arg_list {
+  // Workaround for clang's -Wweak-vtables. Unlike for regular classes, for
+  // templates it doesn't complain about inability to deduce single translation
+  // unit for placing vtable. So storage_node_base is made a fake template.
+  template <typename = void> struct node {
+    virtual ~node() = default;
+    std::unique_ptr<node<>> next;
+  };
+
+  template <typename T> struct typed_node : node<> {
+    T value;
+
+    template <typename Arg>
+    FMT_CONSTEXPR typed_node(const Arg& arg) : value(arg) {}
+
+    template <typename Char>
+    FMT_CONSTEXPR typed_node(const basic_string_view<Char>& arg)
+        : value(arg.data(), arg.size()) {}
+  };
+
+  std::unique_ptr<node<>> head_;
+
+ public:
+  template <typename T, typename Arg> const T& push(const Arg& arg) {
+    auto new_node = std::unique_ptr<typed_node<T>>(new typed_node<T>(arg));
+    auto& value = new_node->value;
+    new_node->next = std::move(head_);
+    head_ = std::move(new_node);
+    return value;
+  }
+};
+}  // namespace detail
+
+// Formatting context.
+template <typename OutputIt, typename Char> class basic_format_context {
+ public:
+  /** The character type for the output. */
+  using char_type = Char;
+
+ private:
+  OutputIt out_;
+  basic_format_args<basic_format_context> args_;
+  detail::locale_ref loc_;
+
+ public:
+  using iterator = OutputIt;
+  using format_arg = basic_format_arg<basic_format_context>;
+  using parse_context_type = basic_format_parse_context<Char>;
+  template <typename T> using formatter_type = formatter<T, char_type>;
+
+  basic_format_context(const basic_format_context&) = delete;
+  void operator=(const basic_format_context&) = delete;
+  /**
+   Constructs a ``basic_format_context`` object. References to the arguments are
+   stored in the object so make sure they have appropriate lifetimes.
+   */
+  basic_format_context(OutputIt out,
+                       basic_format_args<basic_format_context> ctx_args,
+                       detail::locale_ref loc = detail::locale_ref())
+      : out_(out), args_(ctx_args), loc_(loc) {}
+
+  format_arg arg(int id) const { return args_.get(id); }
+  format_arg arg(basic_string_view<char_type> name) { return args_.get(name); }
+  int arg_id(basic_string_view<char_type> name) { return args_.get_id(name); }
+  const basic_format_args<basic_format_context>& args() const { return args_; }
+
+  detail::error_handler error_handler() { return {}; }
+  void on_error(const char* message) { error_handler().on_error(message); }
+
+  // Returns an iterator to the beginning of the output range.
+  iterator out() { return out_; }
+
+  // Advances the begin iterator to ``it``.
+  void advance_to(iterator it) {
+    if (!detail::is_back_insert_iterator<iterator>()) out_ = it;
+  }
+
+  detail::locale_ref locale() { return loc_; }
+};
+
+template <typename Char>
+using buffer_context =
+    basic_format_context<detail::buffer_appender<Char>, Char>;
+using format_context = buffer_context<char>;
+using wformat_context = buffer_context<wchar_t>;
+
+// Workaround an alias issue: https://stackoverflow.com/q/62767544/471164.
+#define FMT_BUFFER_CONTEXT(Char) \
+  basic_format_context<detail::buffer_appender<Char>, Char>
+
+/**
+  \rst
+  An array of references to arguments. It can be implicitly converted into
+  `~fmt::basic_format_args` for passing into type-erased formatting functions
+  such as `~fmt::vformat`.
+  \endrst
+ */
+template <typename Context, typename... Args>
+class format_arg_store
+#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
+    // Workaround a GCC template argument substitution bug.
+    : public basic_format_args<Context>
+#endif
+{
+ private:
+  static const size_t num_args = sizeof...(Args);
+  static const size_t num_named_args = detail::count_named_args<Args...>();
+  static const bool is_packed = num_args <= detail::max_packed_args;
+
+  using value_type = conditional_t<is_packed, detail::value<Context>,
+                                   basic_format_arg<Context>>;
+
+  detail::arg_data<value_type, typename Context::char_type, num_args,
+                   num_named_args>
+      data_;
+
+  friend class basic_format_args<Context>;
+
+  static constexpr unsigned long long desc =
+      (is_packed ? detail::encode_types<Context, Args...>()
+                 : detail::is_unpacked_bit | num_args) |
+      (num_named_args != 0
+           ? static_cast<unsigned long long>(detail::has_named_args_bit)
+           : 0);
+
+ public:
+  format_arg_store(const Args&... args)
+      :
+#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
+        basic_format_args<Context>(*this),
+#endif
+        data_{detail::make_arg<
+            is_packed, Context,
+            detail::mapped_type_constant<Args, Context>::value>(args)...} {
+    detail::init_named_args(data_.named_args(), 0, 0, args...);
+  }
+};
+
+/**
+  \rst
+  Constructs a `~fmt::format_arg_store` object that contains references to
+  arguments and can be implicitly converted to `~fmt::format_args`. `Context`
+  can be omitted in which case it defaults to `~fmt::context`.
+  See `~fmt::arg` for lifetime considerations.
+  \endrst
+ */
+template <typename Context = format_context, typename... Args>
+inline format_arg_store<Context, Args...> make_format_args(
+    const Args&... args) {
+  return {args...};
+}
+
+/**
+  \rst
+  Constructs a `~fmt::format_arg_store` object that contains references
+  to arguments and can be implicitly converted to `~fmt::format_args`.
+  If ``format_str`` is a compile-time string then `make_args_checked` checks
+  its validity at compile time.
+  \endrst
+ */
+template <typename... Args, typename S, typename Char = char_t<S>>
+inline auto make_args_checked(const S& format_str,
+                              const remove_reference_t<Args>&... args)
+    -> format_arg_store<buffer_context<Char>, remove_reference_t<Args>...> {
+  static_assert(
+      detail::count<(
+              std::is_base_of<detail::view, remove_reference_t<Args>>::value &&
+              std::is_reference<Args>::value)...>() == 0,
+      "passing views as lvalues is disallowed");
+  detail::check_format_string<Args...>(format_str);
+  return {args...};
+}
+
+/**
+  \rst
+  Returns a named argument to be used in a formatting function. It should only
+  be used in a call to a formatting function.
+
+  **Example**::
+
+    fmt::print("Elapsed time: {s:.2f} seconds", fmt::arg("s", 1.23));
+  \endrst
+ */
+template <typename Char, typename T>
+inline detail::named_arg<Char, T> arg(const Char* name, const T& arg) {
+  static_assert(!detail::is_named_arg<T>(), "nested named arguments");
+  return {name, arg};
+}
+
+/**
+  \rst
+  A dynamic version of `fmt::format_arg_store`.
+  It's equipped with a storage to potentially temporary objects which lifetimes
+  could be shorter than the format arguments object.
+
+  It can be implicitly converted into `~fmt::basic_format_args` for passing
+  into type-erased formatting functions such as `~fmt::vformat`.
+  \endrst
+ */
+template <typename Context>
+class dynamic_format_arg_store
+#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
+    // Workaround a GCC template argument substitution bug.
+    : public basic_format_args<Context>
+#endif
+{
+ private:
+  using char_type = typename Context::char_type;
+
+  template <typename T> struct need_copy {
+    static constexpr detail::type mapped_type =
+        detail::mapped_type_constant<T, Context>::value;
+
+    enum {
+      value = !(detail::is_reference_wrapper<T>::value ||
+                std::is_same<T, basic_string_view<char_type>>::value ||
+                std::is_same<T, detail::std_string_view<char_type>>::value ||
+                (mapped_type != detail::type::cstring_type &&
+                 mapped_type != detail::type::string_type &&
+                 mapped_type != detail::type::custom_type))
+    };
+  };
+
+  template <typename T>
+  using stored_type = conditional_t<detail::is_string<T>::value,
+                                    std::basic_string<char_type>, T>;
+
+  // Storage of basic_format_arg must be contiguous.
+  std::vector<basic_format_arg<Context>> data_;
+  std::vector<detail::named_arg_info<char_type>> named_info_;
+
+  // Storage of arguments not fitting into basic_format_arg must grow
+  // without relocation because items in data_ refer to it.
+  detail::dynamic_arg_list dynamic_args_;
+
+  friend class basic_format_args<Context>;
+
+  unsigned long long get_types() const {
+    return detail::is_unpacked_bit | data_.size() |
+           (named_info_.empty()
+                ? 0ULL
+                : static_cast<unsigned long long>(detail::has_named_args_bit));
+  }
+
+  const basic_format_arg<Context>* data() const {
+    return named_info_.empty() ? data_.data() : data_.data() + 1;
+  }
+
+  template <typename T> void emplace_arg(const T& arg) {
+    data_.emplace_back(detail::make_arg<Context>(arg));
+  }
+
+  template <typename T>
+  void emplace_arg(const detail::named_arg<char_type, T>& arg) {
+    if (named_info_.empty()) {
+      constexpr const detail::named_arg_info<char_type>* zero_ptr{nullptr};
+      data_.insert(data_.begin(), {zero_ptr, 0});
+    }
+    data_.emplace_back(detail::make_arg<Context>(detail::unwrap(arg.value)));
+    auto pop_one = [](std::vector<basic_format_arg<Context>>* data) {
+      data->pop_back();
+    };
+    std::unique_ptr<std::vector<basic_format_arg<Context>>, decltype(pop_one)>
+        guard{&data_, pop_one};
+    named_info_.push_back({arg.name, static_cast<int>(data_.size() - 2u)});
+    data_[0].value_.named_args = {named_info_.data(), named_info_.size()};
+    guard.release();
+  }
+
+ public:
+  /**
+    \rst
+    Adds an argument into the dynamic store for later passing to a formatting
+    function.
+
+    Note that custom types and string types (but not string views) are copied
+    into the store dynamically allocating memory if necessary.
+
+    **Example**::
+
+      fmt::dynamic_format_arg_store<fmt::format_context> store;
+      store.push_back(42);
+      store.push_back("abc");
+      store.push_back(1.5f);
+      std::string result = fmt::vformat("{} and {} and {}", store);
+    \endrst
+  */
+  template <typename T> void push_back(const T& arg) {
+    if (detail::const_check(need_copy<T>::value))
+      emplace_arg(dynamic_args_.push<stored_type<T>>(arg));
+    else
+      emplace_arg(detail::unwrap(arg));
+  }
+
+  /**
+    \rst
+    Adds a reference to the argument into the dynamic store for later passing to
+    a formatting function. Supports named arguments wrapped in
+    ``std::reference_wrapper`` via ``std::ref()``/``std::cref()``.
+
+    **Example**::
+
+      fmt::dynamic_format_arg_store<fmt::format_context> store;
+      char str[] = "1234567890";
+      store.push_back(std::cref(str));
+      int a1_val{42};
+      auto a1 = fmt::arg("a1_", a1_val);
+      store.push_back(std::cref(a1));
+
+      // Changing str affects the output but only for string and custom types.
+      str[0] = 'X';
+
+      std::string result = fmt::vformat("{} and {a1_}");
+      assert(result == "X234567890 and 42");
+    \endrst
+  */
+  template <typename T> void push_back(std::reference_wrapper<T> arg) {
+    static_assert(
+        detail::is_named_arg<typename std::remove_cv<T>::type>::value ||
+            need_copy<T>::value,
+        "objects of built-in types and string views are always copied");
+    emplace_arg(arg.get());
+  }
+
+  /**
+    Adds named argument into the dynamic store for later passing to a formatting
+    function. ``std::reference_wrapper`` is supported to avoid copying of the
+    argument.
+  */
+  template <typename T>
+  void push_back(const detail::named_arg<char_type, T>& arg) {
+    const char_type* arg_name =
+        dynamic_args_.push<std::basic_string<char_type>>(arg.name).c_str();
+    if (detail::const_check(need_copy<T>::value)) {
+      emplace_arg(
+          fmt::arg(arg_name, dynamic_args_.push<stored_type<T>>(arg.value)));
+    } else {
+      emplace_arg(fmt::arg(arg_name, arg.value));
+    }
+  }
+
+  /** Erase all elements from the store */
+  void clear() {
+    data_.clear();
+    named_info_.clear();
+    dynamic_args_ = detail::dynamic_arg_list();
+  }
+
+  /**
+    \rst
+    Reserves space to store at least *new_cap* arguments including
+    *new_cap_named* named arguments.
+    \endrst
+  */
+  void reserve(size_t new_cap, size_t new_cap_named) {
+    FMT_ASSERT(new_cap >= new_cap_named,
+               "Set of arguments includes set of named arguments");
+    data_.reserve(new_cap);
+    named_info_.reserve(new_cap_named);
+  }
+};
+
+/**
+  \rst
+  A view of a collection of formatting arguments. To avoid lifetime issues it
+  should only be used as a parameter type in type-erased functions such as
+  ``vformat``::
+
+    void vlog(string_view format_str, format_args args);  // OK
+    format_args args = make_format_args(42);  // Error: dangling reference
+  \endrst
+ */
+template <typename Context> class basic_format_args {
+ public:
+  using size_type = int;
+  using format_arg = basic_format_arg<Context>;
+
+ private:
+  // A descriptor that contains information about formatting arguments.
+  // If the number of arguments is less or equal to max_packed_args then
+  // argument types are passed in the descriptor. This reduces binary code size
+  // per formatting function call.
+  unsigned long long desc_;
+  union {
+    // If is_packed() returns true then argument values are stored in values_;
+    // otherwise they are stored in args_. This is done to improve cache
+    // locality and reduce compiled code size since storing larger objects
+    // may require more code (at least on x86-64) even if the same amount of
+    // data is actually copied to stack. It saves ~10% on the bloat test.
+    const detail::value<Context>* values_;
+    const format_arg* args_;
+  };
+
+  bool is_packed() const { return (desc_ & detail::is_unpacked_bit) == 0; }
+  bool has_named_args() const {
+    return (desc_ & detail::has_named_args_bit) != 0;
+  }
+
+  detail::type type(int index) const {
+    int shift = index * detail::packed_arg_bits;
+    unsigned int mask = (1 << detail::packed_arg_bits) - 1;
+    return static_cast<detail::type>((desc_ >> shift) & mask);
+  }
+
+  basic_format_args(unsigned long long desc,
+                    const detail::value<Context>* values)
+      : desc_(desc), values_(values) {}
+  basic_format_args(unsigned long long desc, const format_arg* args)
+      : desc_(desc), args_(args) {}
+
+ public:
+  basic_format_args() : desc_(0) {}
+
+  /**
+   \rst
+   Constructs a `basic_format_args` object from `~fmt::format_arg_store`.
+   \endrst
+   */
+  template <typename... Args>
+  FMT_INLINE basic_format_args(const format_arg_store<Context, Args...>& store)
+      : basic_format_args(store.desc, store.data_.args()) {}
+
+  /**
+   \rst
+   Constructs a `basic_format_args` object from
+   `~fmt::dynamic_format_arg_store`.
+   \endrst
+   */
+  FMT_INLINE basic_format_args(const dynamic_format_arg_store<Context>& store)
+      : basic_format_args(store.get_types(), store.data()) {}
+
+  /**
+   \rst
+   Constructs a `basic_format_args` object from a dynamic set of arguments.
+   \endrst
+   */
+  basic_format_args(const format_arg* args, int count)
+      : basic_format_args(detail::is_unpacked_bit | detail::to_unsigned(count),
+                          args) {}
+
+  /** Returns the argument with the specified id. */
+  format_arg get(int id) const {
+    format_arg arg;
+    if (!is_packed()) {
+      if (id < max_size()) arg = args_[id];
+      return arg;
+    }
+    if (id >= detail::max_packed_args) return arg;
+    arg.type_ = type(id);
+    if (arg.type_ == detail::type::none_type) return arg;
+    arg.value_ = values_[id];
+    return arg;
+  }
+
+  template <typename Char> format_arg get(basic_string_view<Char> name) const {
+    int id = get_id(name);
+    return id >= 0 ? get(id) : format_arg();
+  }
+
+  template <typename Char> int get_id(basic_string_view<Char> name) const {
+    if (!has_named_args()) return -1;
+    const auto& named_args =
+        (is_packed() ? values_[-1] : args_[-1].value_).named_args;
+    for (size_t i = 0; i < named_args.size; ++i) {
+      if (named_args.data[i].name == name) return named_args.data[i].id;
+    }
+    return -1;
+  }
+
+  int max_size() const {
+    unsigned long long max_packed = detail::max_packed_args;
+    return static_cast<int>(is_packed() ? max_packed
+                                        : desc_ & ~detail::is_unpacked_bit);
+  }
+};
+
+#ifdef FMT_ARM_ABI_COMPATIBILITY
+/** An alias to ``basic_format_args<format_context>``. */
+// Separate types would result in shorter symbols but break ABI compatibility
+// between clang and gcc on ARM (#1919).
+using format_args = basic_format_args<format_context>;
+using wformat_args = basic_format_args<wformat_context>;
+#else
+// DEPRECATED! These are kept for ABI compatibility.
+// It is a separate type rather than an alias to make symbols readable.
+struct format_args : basic_format_args<format_context> {
+  template <typename... Args>
+  FMT_INLINE format_args(const Args&... args) : basic_format_args(args...) {}
+};
+struct wformat_args : basic_format_args<wformat_context> {
+  using basic_format_args::basic_format_args;
+};
+#endif
+
+namespace detail {
+
+template <typename Char, FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
+std::basic_string<Char> vformat(
+    basic_string_view<Char> format_str,
+    basic_format_args<buffer_context<type_identity_t<Char>>> args);
+
+FMT_API std::string vformat(string_view format_str, format_args args);
+
+template <typename Char>
+void vformat_to(
+    buffer<Char>& buf, basic_string_view<Char> format_str,
+    basic_format_args<FMT_BUFFER_CONTEXT(type_identity_t<Char>)> args,
+    detail::locale_ref loc = {});
+
+template <typename Char, typename Args,
+          FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
+inline void vprint_mojibake(std::FILE*, basic_string_view<Char>, const Args&) {}
+
+FMT_API void vprint_mojibake(std::FILE*, string_view, format_args);
+#ifndef _WIN32
+inline void vprint_mojibake(std::FILE*, string_view, format_args) {}
+#endif
+}  // namespace detail
+
+/** Formats a string and writes the output to ``out``. */
+// GCC 8 and earlier cannot handle std::back_insert_iterator<Container> with
+// vformat_to<ArgFormatter>(...) overload, so SFINAE on iterator type instead.
+template <typename OutputIt, typename S, typename Char = char_t<S>,
+          bool enable = detail::is_output_iterator<OutputIt, Char>::value>
+auto vformat_to(OutputIt out, const S& format_str,
+                basic_format_args<buffer_context<type_identity_t<Char>>> args)
+    -> typename std::enable_if<enable, OutputIt>::type {
+  decltype(detail::get_buffer<Char>(out)) buf(detail::get_buffer_init(out));
+  detail::vformat_to(buf, to_string_view(format_str), args);
+  return detail::get_iterator(buf);
+}
+
+/**
+ \rst
+ Formats arguments, writes the result to the output iterator ``out`` and returns
+ the iterator past the end of the output range.
+
+ **Example**::
+
+   std::vector<char> out;
+   fmt::format_to(std::back_inserter(out), "{}", 42);
+ \endrst
+ */
+// We cannot use FMT_ENABLE_IF because of a bug in gcc 8.3.
+template <typename OutputIt, typename S, typename... Args,
+          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value>
+inline auto format_to(OutputIt out, const S& format_str, Args&&... args) ->
+    typename std::enable_if<enable, OutputIt>::type {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return vformat_to(out, to_string_view(format_str), vargs);
+}
+
+template <typename OutputIt> struct format_to_n_result {
+  /** Iterator past the end of the output range. */
+  OutputIt out;
+  /** Total (not truncated) output size. */
+  size_t size;
+};
+
+template <typename OutputIt, typename Char, typename... Args,
+          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value)>
+inline format_to_n_result<OutputIt> vformat_to_n(
+    OutputIt out, size_t n, basic_string_view<Char> format_str,
+    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+  detail::iterator_buffer<OutputIt, Char, detail::fixed_buffer_traits> buf(out,
+                                                                           n);
+  detail::vformat_to(buf, format_str, args);
+  return {buf.out(), buf.count()};
+}
+
+/**
+ \rst
+ Formats arguments, writes up to ``n`` characters of the result to the output
+ iterator ``out`` and returns the total output size and the iterator past the
+ end of the output range.
+ \endrst
+ */
+template <typename OutputIt, typename S, typename... Args,
+          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value>
+inline auto format_to_n(OutputIt out, size_t n, const S& format_str,
+                        const Args&... args) ->
+    typename std::enable_if<enable, format_to_n_result<OutputIt>>::type {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return vformat_to_n(out, n, to_string_view(format_str), vargs);
+}
+
+/**
+  Returns the number of characters in the output of
+  ``format(format_str, args...)``.
+ */
+template <typename... Args>
+inline size_t formatted_size(string_view format_str, Args&&... args) {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  detail::counting_buffer<> buf;
+  detail::vformat_to(buf, format_str, vargs);
+  return buf.count();
+}
+
+template <typename S, typename Char = char_t<S>>
+FMT_INLINE std::basic_string<Char> vformat(
+    const S& format_str,
+    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+  return detail::vformat(to_string_view(format_str), args);
+}
+
+/**
+  \rst
+  Formats arguments and returns the result as a string.
+
+  **Example**::
+
+    #include <fmt/core.h>
+    std::string message = fmt::format("The answer is {}", 42);
+  \endrst
+*/
+// Pass char_t as a default template parameter instead of using
+// std::basic_string<char_t<S>> to reduce the symbol size.
+template <typename S, typename... Args, typename Char = char_t<S>>
+FMT_INLINE std::basic_string<Char> format(const S& format_str, Args&&... args) {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return detail::vformat(to_string_view(format_str), vargs);
+}
+
+FMT_API void vprint(string_view, format_args);
+FMT_API void vprint(std::FILE*, string_view, format_args);
+
+/**
+  \rst
+  Formats ``args`` according to specifications in ``format_str`` and writes the
+  output to the file ``f``. Strings are assumed to be Unicode-encoded unless the
+  ``FMT_UNICODE`` macro is set to 0.
+
+  **Example**::
+
+    fmt::print(stderr, "Don't {}!", "panic");
+  \endrst
+ */
+template <typename S, typename... Args, typename Char = char_t<S>>
+inline void print(std::FILE* f, const S& format_str, Args&&... args) {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return detail::is_unicode<Char>()
+             ? vprint(f, to_string_view(format_str), vargs)
+             : detail::vprint_mojibake(f, to_string_view(format_str), vargs);
+}
+
+/**
+  \rst
+  Formats ``args`` according to specifications in ``format_str`` and writes
+  the output to ``stdout``. Strings are assumed to be Unicode-encoded unless
+  the ``FMT_UNICODE`` macro is set to 0.
+
+  **Example**::
+
+    fmt::print("Elapsed time: {0:.2f} seconds", 1.23);
+  \endrst
+ */
+template <typename S, typename... Args, typename Char = char_t<S>>
+inline void print(const S& format_str, Args&&... args) {
+  const auto& vargs = fmt::make_args_checked<Args...>(format_str, args...);
+  return detail::is_unicode<Char>()
+             ? vprint(to_string_view(format_str), vargs)
+             : detail::vprint_mojibake(stdout, to_string_view(format_str),
+                                       vargs);
+}
+FMT_END_NAMESPACE
+
+#endif  // FMT_CORE_H_