9.0.0

• Switched to the internal floating point formatter for all decimal presentation formats. In particular this results in consistent rounding on all platforms and removing the s[n]printf fallback for decimal FP formatting.

• Compile-time floating point formatting no longer requires the header-only mode. For example (godbolt):

  #include <array>
  #include <fmt/compile.h>
  
  consteval auto compile_time_dtoa(double value) -> std::array<char, 10> {
    auto result = std::array<char, 10>();
    fmt::format_to(result.data(), FMT_COMPILE("{}"), value);
    return result;
  }
  
  constexpr auto answer = compile_time_dtoa(0.42);

  works with the default settings.

• Improved the implementation of Dragonbox, the algorithm used for the default floating-point formatting (#2713, #2750). Thanks @jk-jeon (Junekey Jeon).

• Made fmt::to_string work with __float128. This uses the internal FP formatter and works even on system without __float128 support in [s]printf.

• Disabled automatic std::ostream insertion operator (operator<<) discovery when fmt/ostream.h is included to prevent ODR violations. You can get the old behavior by defining FMT_DEPRECATED_OSTREAM but this will be removed in the next major release. Use fmt::streamed or fmt::ostream_formatter to enable formatting via std::ostream instead.

• Added fmt::ostream_formatter that can be used to write formatter specializations that perform formatting via std::ostream. For example (godbolt):

  #include <fmt/ostream.h>
  
  struct date {
    int year, month, day;
  
    friend std::ostream& operator<<(std::ostream& os, const date& d) {
      return os << d.year << '-' << d.month << '-' << d.day;
    }
  };
  
  template <> struct fmt::formatter<date> : ostream_formatter {};
  
  std::string s = fmt::format("The date is {}", date{2012, 12, 9});
  // s == "The date is 2012-12-9"

• Added the fmt::streamed function that takes an object and formats it via std::ostream. For example (godbolt):

  #include <thread>
  #include <fmt/ostream.h>
  
  int main() {
    fmt::print("Current thread id: {}\n",
               fmt::streamed(std::this_thread::get_id()));
  }

  Note that fmt/std.h provides a formatter specialization for std::thread::id so you don't need to format it via std::ostream.

• Deprecated implicit conversions of unscoped enums to integers for consistency with scoped enums.

• Added an argument-dependent lookup based format_as extension API to simplify formatting of enums.

• Added experimental std::variant formatting support (#2941). For example (godbolt):

  #include <variant>
  #include <fmt/std.h>
  
  int main() {
    auto v = std::variant<int, std::string>(42);
    fmt::print("{}\n", v);
  }

  prints:

  variant(42)
  

  Thanks @jehelset.

• Added experimental std::filesystem::path formatting support (#2865, #2902, #2917, #2918). For example (godbolt):

  #include <filesystem>
  #include <fmt/std.h>
  
  int main() {
    fmt::print("There is no place like {}.", std::filesystem::path("/home"));
  }

  prints:

  There is no place like "/home".
  

  Thanks @phprus (Vladislav Shchapov).

• Added a std::thread::id formatter to fmt/std.h. For example (godbolt):

  #include <thread>
  #include <fmt/std.h>
  
  int main() {
    fmt::print("Current thread id: {}\n", std::this_thread::get_id());
  }

• Added fmt::styled that applies a text style to an individual argument (#2793). For example (godbolt):

  #include <fmt/chrono.h>
  #include <fmt/color.h>
  
  int main() {
    auto now = std::chrono::system_clock::now();
    fmt::print(
      "[{}] {}: {}\n",
      fmt::styled(now, fmt::emphasis::bold),
      fmt::styled("error", fg(fmt::color::red)),
      "something went wrong");
  }

  prints

  Thanks @rbrugo (Riccardo Brugo).

• Made fmt::print overload for text styles correctly handle UTF-8 (#2681, #2701). Thanks @AlexGuteniev (Alex Guteniev).

• Fixed Unicode handling when writing to an ostream.

• Added support for nested specifiers to range formatting (#2673). For example (godbolt):

  #include <vector>
  #include <fmt/ranges.h>
  
  int main() {
    fmt::print("{::#x}\n", std::vector{10, 20, 30});
  }

  prints [0xa, 0x14, 0x1e].

  Thanks @BRevzin (Barry Revzin).

• Implemented escaping of wide strings in ranges (#2904). Thanks @phprus (Vladislav Shchapov).

• Added support for ranges with begin / end found via the argument-dependent lookup (#2807). Thanks @rbrugo (Riccardo Brugo).

• Fixed formatting of certain kinds of ranges of ranges (#2787). Thanks @BRevzin (Barry Revzin).

• Fixed handling of maps with element types other than std::pair (#2944). Thanks @BrukerJWD (Jonathan W).

• Made tuple formatter enabled only if elements are formattable (#2939, #2940). Thanks @jehelset.

• Made fmt::join compatible with format string compilation (#2719, #2720). Thanks @phprus (Vladislav Shchapov).

• Made compile-time checks work with named arguments of custom types and std::ostream print overloads (#2816, #2817, #2819). Thanks @timsong-cpp.

• Removed make_args_checked because it is no longer needed for compile-time checks (#2760). Thanks @phprus (Vladislav Shchapov).

• Removed the following deprecated APIs: _format, arg_join, the format_to overload that takes a memory buffer, [v]fprintf that takes an ostream.

• Removed the deprecated implicit conversion of [const] signed char* and [const] unsigned char* to C strings.

• Removed the deprecated fmt/locale.h.

• Replaced the deprecated fileno() with descriptor() in buffered_file.

• Moved to_string_view to the detail namespace since it's an implementation detail.

• Made access mode of a created file consistent with fopen by setting S_IWGRP and S_IWOTH (#2733). Thanks @arogge (Andreas Rogge).

• Removed a redundant buffer resize when formatting to std::ostream (#2842, #2843). Thanks @jcelerier (Jean-Michaël Celerier).

• Made precision computation for strings consistent with width (#2888).

• Fixed handling of locale separators in floating point formatting (#2830).

• Made sign specifiers work with __int128_t (#2773).

• Improved support for systems such as CHERI with extra data stored in pointers (#2932). Thanks @davidchisnall (David Chisnall).

• Improved documentation (#2706, #2712, #2789, #2803, #2805, #2815, #2924). Thanks @BRevzin (Barry Revzin), @Pokechu22, @setoye (Alta), @rtobar, @rbrugo (Riccardo Brugo), @anoonD (cre), @leha-bot (Alex).

• Improved build configuration (#2766, #2772, #2836, #2852, #2907, #2913, #2914). Thanks @kambala-decapitator (Andrey Filipenkov), @mattiasljungstrom (Mattias Ljungström), @kieselnb (Nick Kiesel), @nathannaveen, @Vertexwahn.

• Fixed various warnings and compilation issues (#2408, #2507, #2697, #2715, #2717, #2722, #2724, #2725, #2726, #2728, #2732, #2738, #2742, #2744, #2745, #2746, #2754, #2755, #2757, #2758, #2761, #2762, #2763, #2765, #2769, #2770, #2771, #2777, #2779, #2782, #2783, #2794, #2796, #2797, #2801, #2802, #2808, #2818, #2819, #2829, #2835, #2848, #2860, #2861, #2882, #2886, #2891, #2892, #2895, #2896, #2903, #2906, #2908, #2909, #2920, #2922, #2927, #2929, #2936, #2937, #2938, #2951, #2954, #2957, #2958, #2960). Thanks @matrackif @Tobi823 (Tobias Hellmann), @ivan-volnov (Ivan Volnov), @VasiliPupkin256, @federico-busato (Federico), @barcharcraz (Charlie Barto), @jk-jeon (Junekey Jeon), @HazardyKnusperkeks (Björn Schäpers), @dalboris (Boris Dalstein), @seanm (Sean McBride), @gsjaardema (Greg Sjaardema), @timsong-cpp, @seanm (Sean McBride), @frithrah, @chronoxor (Ivan Shynkarenka), @Agga, @madmaxoft (Mattes D), @JurajX (Juraj), @phprus (Vladislav Shchapov), @Dani-Hub (Daniel Krügler).

Pull Requests

• Make colored print handle UTF-8 by @AlexGuteniev in #2701
• Supporting nested format specs for ranges. by @brevzin in #2673
• Adding comments for range formatting. by @brevzin in #2706
• Docs: Fix link to "Compile-time Format String Checks" section by @Pokechu22 in #2712
• fmt::join support FMT_COMPILE by @phprus in #2720
• Fix overflow for chrono durations by @matrackif in #2722
• Fix -Wconversion warning by @Tobi823 in #2724
• Fix codecvt warning (#2408) by @ivan-volnov in #2725
• Simplify Dragonbox by @jk-jeon in #2713
• Making target_compile_options PRIVATE, fix #2726, fix #2507 by @VasiliPupkin256 in #2728
• Fixes NVIDIA HPC compiler and Intel ICC compatibility by @federico-busato in #2732
• Fix access mode of files created (#2530) by @arogge in #2733
• Supporting ? as a string presentation type by @brevzin in #2674
• qualify unqualified calls to format in compile.h by @barcharcraz in #2742
• Add missing const qualifier by @phprus in #2755
• Workaround for Intel compiler by @phprus in #2758
• Reflect the new paper on Dragonbox by @jk-jeon in #2750
• Replace make_args_checked with make_format_args by @phprus in #2760
• Address Issue #2763 by @jk-jeon in #2765
• Update .bazelversion by @Vertexwahn in #2766
• Clz builtin may be not constexpr by @phprus in #2762
• Apply 2746 fix for NVidia compiler also by @gsjaardema in #2770
• add ability to build library as Apple framework by @kambala-decapitator in #2772
• Ignore clang -Wliteral-range warning by @phprus in #2779
• Fixing "C4127: conditional expression is constant" Visual Studio 2022 warning in pedantic mode by @chronoxor in #2783
• Fix Conversion by @HazardyKnusperkeks in #2782
• fix typo by @setoye in #2789
• Fixing formatting of certain kinds of ranges of ranges. by @brevzin in #2787
• Fix warning C4251: class fmt::v8::file needs to have dll-interface by @dalboris in #2797
• Eliminate intel compiler warnings by @gsjaardema in #2802
• Implement styled arguments by @rbrugo in #2793
• Document output_file default behavior correctly by @rtobar in #2803
• Add styled in documentation by @rbrugo in #2805
• Fix compilation error for ranges with ADL begin/end by @rbrugo in #2807
• Update color.h by @anoonD in #2815
• Fixes for #2816/2817/2818 by @timsong-cpp in #2819
• Misc warnings by @seanm in #2801
• Fix incompatible between Jinja2 >= 3.1 and sphinx 3.3.0 by @phprus in #2836
• Remove dead code in ostream.h format_value by @jcelerier in #2843
• MSVC CMake generation optimization (13.6s -> 5.7s) by @mattiasljungstrom in #2852
• Suppress a -Wliteral-range warning on Apple M1 by @phprus in #2861
• Fixed all clang -Wsigned-enum-bitfield warnings by @seanm in #2882
• VS2022 17.2: C4189: 'zero': local variable is initialized but not referenced #2891 by @chronoxor in #2892
• Fix Windows max mix-up in chrono by @frithrah in #2903
• Skip cmake targets inclusion if fmt::fmt already exists by @kieselnb in #2907
• Add xchar support for write_escaped_string. by @phprus in #2904
• Visual Studio 2022: fmt/format.h(1526,27): warning C4127: conditional expression is constant #2908 by @chronoxor in #2909
• Improve std formatters by @phprus in #2902
• chore: Set permissions for GitHub actions by @nathannaveen in #2913
• Add support for std.h in Bazel build by @Vertexwahn in #2914
• use qualified format_to call to avoid ADL conflict with std::format_to by @Agga in #2922
• Docs: add comment about empty format context range by @leha-bot in #2924
• Make std::filesystem::path formatter utf-8 compatible. by @phprus in #2918
• Fix 'duplicate symbol' error. by @phprus in #2927
• Added a FMT_STRING wrapper for system_error() call. by @madmaxoft in #2929
• Make the tests pass on a CHERI system. by @davidchisnall in #2932
• fix -Wsign-conversion warnings by @JurajX in #2937
• Remove /source-charset:utf-8 compile option. by @phprus in #2938
• Fix is_formattable for tuple-like types. by @jehelset in #2940
• Fix enable_ifs for map formatter: map formatter requires std::pair formatter but never uses it by @BrukerJWD in #2944
• Add support for 'std::variant' in C++17 by @jehelset in #2941
• Fix std::variant, std::filesystem::path tests on GCC-8, Clang-7,8. by @phprus in #2951
• Fix partial specialization problem for filesystem for Visual Studio by @Dani-Hub in #2957
• Add support Microsoft Visual Studio 2022. by @phprus in #2960

New Contributors

• @Pokechu22 made their first contribution in #2712
• @Tobi823 made their first contribution in #2724
• @ivan-volnov made their first contribution in #2725
• @VasiliPupkin256 made their first contribution in #2728
• @arogge made their first contribution in #2733
• @barcharcraz made their first contribution in #2742
• @kambala-decapitator made their first contribution in #2772
• @setoye made their first contribution in #2789
• @dalboris made their first contribution in #2797
• @rbrugo made their first contribution in #2793
• @rtobar made their first contribution in #2803
• @anoonD made their first contribution in #2815
• @timsong-cpp made their first contribution in #2819
• @seanm made their first contribution in #2801
• @frithrah made their first contribution in #2903
• @kieselnb made their first contribution in #2907
• @nathannaveen made their first contribution in #2913
• @Agga made their first contribution in #2922
• @leha-bot made their first contribution in #2924
• @madmaxoft made their first contribution in #2929
• @davidchisnall made their first contribution in #2932
• @JurajX made their first contribution in #2937
• @jehelset made their first contribution in #2940
• @Dani-Hub made their first contribution in #2957

Full Changelog: 8.1.1...9.0.0