C++ Format changelog

Changelog History

Page 1

• v9.1.0 Changes

  August 27, 2022

  • fmt::formatted_size now works at compile time (#3026 <https://github.com/fmtlib/fmt/pull/3026>). For example (godbolt <https://godbolt.org/z/1MW5rMdf8>_):

  .. code:: c++

   #include <fmt/compile.h>
  
   int main() {
     using namespace fmt::literals;
     constexpr size_t n = fmt::formatted_size("{}"_cf, 42);
     fmt::print("{}\n", n); // prints 2
   }
  

  Thanks @marksantaniello (Mark Santaniello) <https://github.com/marksantaniello>_.

  • 🛠 Fixed handling of invalid UTF-8 (#3038 <https://github.com/fmtlib/fmt/pull/3038>, #3044 <https://github.com/fmtlib/fmt/pull/3044>, #3056 <https://github.com/fmtlib/fmt/pull/3056>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus> and @skeeto (Christopher Wellons) <https://github.com/skeeto>_.

  • 👌 Improved Unicode support in ostream overloads of print (#2994 <https://github.com/fmtlib/fmt/pull/2994>, #3001 <https://github.com/fmtlib/fmt/pull/3001>, #3025 <https://github.com/fmtlib/fmt/pull/3025>). Thanks @dimztimz (Dimitrij Mijoski) <https://github.com/dimztimz>.

  • 🛠 Fixed handling of the sign specifier in localized formatting on systems with 32-bit wchar_t (#3041 <https://github.com/fmtlib/fmt/issues/3041>_).

  • ➕ Added support for wide streams to fmt::streamed (#2994 <https://github.com/fmtlib/fmt/pull/2994>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>.

  • ➕ Added the n specifier that disables the output of delimiters when formatting ranges (#2981 <https://github.com/fmtlib/fmt/pull/2981>, #2983 <https://github.com/fmtlib/fmt/pull/2983>). For example (godbolt <https://godbolt.org/z/roKqGdj8c>__):

  .. code:: c++

   #include <fmt/ranges.h>
   #include <vector>
  
   int main() {
     auto v = std::vector{1, 2, 3};
     fmt::print("{:n}\n", v); // prints 1, 2, 3
   }
  

  Thanks @BRevzin (Barry Revzin) <https://github.com/BRevzin>_.

  • Worked around problematic std::string_view constructors introduced in C++23 (#3030 <https://github.com/fmtlib/fmt/issues/3030>, #3050 <https://github.com/fmtlib/fmt/issues/3050>). Thanks @strega-nil-ms (nicole mazzuca) <https://github.com/strega-nil-ms>_.

  • 👌 Improve handling (exclusion) of recursive ranges (#2968 <https://github.com/fmtlib/fmt/issues/2968>, #2974 <https://github.com/fmtlib/fmt/pull/2974>). Thanks @Dani-Hub (Daniel Krügler) <https://github.com/Dani-Hub>_.

  • 👌 Improved error reporting in format string compilation (#3055 <https://github.com/fmtlib/fmt/issues/3055>_).

  • 👌 Improved the implementation of Dragonbox <https://github.com/jk-jeon/dragonbox>, the algorithm used for the default floating-point formatting (#2984 <https://github.com/fmtlib/fmt/pull/2984>). Thanks @jk-jeon (Junekey Jeon) <https://github.com/jk-jeon>_.

  • 🛠 Fixed issues with floating-point formatting on exotic platforms.

  • 👌 Improved the implementation of chrono formatting (#3010 <https://github.com/fmtlib/fmt/pull/3010>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>.

  • 👌 Improved documentation (#2966 <https://github.com/fmtlib/fmt/pull/2966>, #3009 <https://github.com/fmtlib/fmt/pull/3009>, #3020 <https://github.com/fmtlib/fmt/issues/3020>, #3037 <https://github.com/fmtlib/fmt/pull/3037>). Thanks @mwinterb <https://github.com/mwinterb>, @jcelerier (Jean-Michaël Celerier) <https://github.com/jcelerier> and @remiburtin (Rémi Burtin) <https://github.com/remiburtin>_.

  • 👌 Improved build configuration (#2991 <https://github.com/fmtlib/fmt/pull/2991>, #2995 <https://github.com/fmtlib/fmt/pull/2995>, #3004 <https://github.com/fmtlib/fmt/issues/3004>, #3007 <https://github.com/fmtlib/fmt/pull/3007>, #3040 <https://github.com/fmtlib/fmt/pull/3040>). Thanks @dimztimz (Dimitrij Mijoski) <https://github.com/dimztimz> and @hwhsu1231 (Haowei Hsu) <https://github.com/hwhsu1231>_.

  • 🛠 Fixed various warnings and compilation issues (#2969 <https://github.com/fmtlib/fmt/issues/2969>, #2971 <https://github.com/fmtlib/fmt/pull/2971>, #2975 <https://github.com/fmtlib/fmt/issues/2975>, #2982 <https://github.com/fmtlib/fmt/pull/2982>, #2985 <https://github.com/fmtlib/fmt/pull/2985>, #2988 <https://github.com/fmtlib/fmt/issues/2988>, #3000 <https://github.com/fmtlib/fmt/issues/3000>, #3006 <https://github.com/fmtlib/fmt/issues/3006>, #3014 <https://github.com/fmtlib/fmt/issues/3014>, #3015 <https://github.com/fmtlib/fmt/issues/3015>, #3021 <https://github.com/fmtlib/fmt/pull/3021>, #3023 <https://github.com/fmtlib/fmt/issues/3023>, #3024 <https://github.com/fmtlib/fmt/pull/3024>, #3029 <https://github.com/fmtlib/fmt/pull/3029>, #3043 <https://github.com/fmtlib/fmt/pull/3043>, #3052 <https://github.com/fmtlib/fmt/issues/3052>, #3053 <https://github.com/fmtlib/fmt/pull/3053>, #3054 <https://github.com/fmtlib/fmt/pull/3054>). Thanks @h-friederich (Hannes Friederich) <https://github.com/h-friederich>, @dimztimz (Dimitrij Mijoski) <https://github.com/dimztimz>, @olupton (Olli Lupton) <https://github.com/olupton>, @bernhardmgruber (Bernhard Manfred Gruber) <https://github.com/bernhardmgruber>, @phprus (Vladislav Shchapov) <https://github.com/phprus>_.

• v9.0.0 Changes

  July 04, 2022

  • 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 <https://godbolt.org/z/G37PTeG3b>__):

  .. code:: c++

   #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 <https://github.com/jk-jeon/dragonbox>, the algorithm used for the default floating-point formatting (#2713 <https://github.com/fmtlib/fmt/pull/2713>, #2750 <https://github.com/fmtlib/fmt/pull/2750>). Thanks @jk-jeon (Junekey Jeon) <https://github.com/jk-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 <https://godbolt.org/z/5sEc5qMsf>__):

  .. code:: c++

   #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 <https://godbolt.org/z/5G3346G1f>__):

  .. code:: c++

   #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 <https://github.com/fmtlib/fmt/pull/2941>). For example (godbolt <https://godbolt.org/z/KG9z6cq68>_):

  .. code:: c++

   #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 <https://github.com/jehelset>_.

  • ➕ Added experimental std::filesystem::path formatting support (#2865 <https://github.com/fmtlib/fmt/issues/2865>, #2902 <https://github.com/fmtlib/fmt/pull/2902>, #2917 <https://github.com/fmtlib/fmt/issues/2917>, #2918 <https://github.com/fmtlib/fmt/pull/2918>). For example (godbolt <https://godbolt.org/z/o44dMexEb>__):

  .. code:: c++

   #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) <https://github.com/phprus>_.

  • ➕ Added a std::thread::id formatter to fmt/std.h. For example (godbolt <https://godbolt.org/z/j1azbYf3E>__):

  .. code:: c++

   #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 <https://github.com/fmtlib/fmt/pull/2793>). For example (godbolt <https://godbolt.org/z/vWGW7v5M6>_):

  .. code:: c++

   #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

  .. image:: https://user-images.githubusercontent.com/576385/ 175071215-12809244-dab0-4005-96d8-7cd911c964d5.png

  Thanks @rbrugo (Riccardo Brugo) <https://github.com/rbrugo>_.

  • 💅 Made fmt::print overload for text styles correctly handle UTF-8 (#2681 <https://github.com/fmtlib/fmt/issues/2681>, #2701 <https://github.com/fmtlib/fmt/pull/2701>). Thanks @AlexGuteniev (Alex Guteniev) <https://github.com/AlexGuteniev>_.

  • 🛠 Fixed Unicode handling when writing to an ostream.

  • ➕ Added support for nested specifiers to range formatting (#2673 <https://github.com/fmtlib/fmt/pull/2673>). For example (godbolt <https://godbolt.org/z/xd3Gj38cf>_):

  .. code:: c++

   #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) <https://github.com/BRevzin>_.

  • Implemented escaping of wide strings in ranges (#2904 <https://github.com/fmtlib/fmt/pull/2904>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>.

  • ➕ Added support for ranges with begin / end found via the argument-dependent lookup (#2807 <https://github.com/fmtlib/fmt/pull/2807>). Thanks @rbrugo (Riccardo Brugo) <https://github.com/rbrugo>.

  • 🛠 Fixed formatting of certain kinds of ranges of ranges (#2787 <https://github.com/fmtlib/fmt/pull/2787>). Thanks @BRevzin (Barry Revzin) <https://github.com/BRevzin>.

  • 🛠 Fixed handling of maps with element types other than std::pair (#2944 <https://github.com/fmtlib/fmt/pull/2944>). Thanks @BrukerJWD (Jonathan W) <https://github.com/BrukerJWD>.

  • Made tuple formatter enabled only if elements are formattable (#2939 <https://github.com/fmtlib/fmt/issues/2939>, #2940 <https://github.com/fmtlib/fmt/pull/2940>). Thanks @jehelset <https://github.com/jehelset>_.

  • Made fmt::join compatible with format string compilation (#2719 <https://github.com/fmtlib/fmt/issues/2719>, #2720 <https://github.com/fmtlib/fmt/pull/2720>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>_.

  • Made compile-time checks work with named arguments of custom types and std::ostream print overloads (#2816 <https://github.com/fmtlib/fmt/issues/2816>, #2817 <https://github.com/fmtlib/fmt/issues/2817>, #2819 <https://github.com/fmtlib/fmt/pull/2819>). Thanks @timsong-cpp <https://github.com/timsong-cpp>.

  • Removed make_args_checked because it is no longer needed for compile-time checks (#2760 <https://github.com/fmtlib/fmt/pull/2760>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>.

  • 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 <https://github.com/fmtlib/fmt/pull/2733>). Thanks @arogge (Andreas Rogge) <https://github.com/arogge>.

  • ✂ Removed a redundant buffer resize when formatting to std::ostream (#2842 <https://github.com/fmtlib/fmt/issues/2842>, #2843 <https://github.com/fmtlib/fmt/pull/2843>). Thanks @jcelerier (Jean-Michaël Celerier) <https://github.com/jcelerier>_.

  • Made precision computation for strings consistent with width (#2888 <https://github.com/fmtlib/fmt/issues/2888>_).

  • 🛠 Fixed handling of locale separators in floating point formatting (#2830 <https://github.com/fmtlib/fmt/issues/2830>_).

  • Made sign specifiers work with __int128_t (#2773 <https://github.com/fmtlib/fmt/issues/2773>_).

  • 👌 Improved support for systems such as CHERI with extra data stored in pointers (#2932 <https://github.com/fmtlib/fmt/pull/2932>). Thanks @davidchisnall (David Chisnall) <https://github.com/davidchisnall>.

  • 👌 Improved documentation (#2706 <https://github.com/fmtlib/fmt/pull/2706>, #2712 <https://github.com/fmtlib/fmt/pull/2712>, #2789 <https://github.com/fmtlib/fmt/pull/2789>, #2803 <https://github.com/fmtlib/fmt/pull/2803>, #2805 <https://github.com/fmtlib/fmt/pull/2805>, #2815 <https://github.com/fmtlib/fmt/pull/2815>, #2924 <https://github.com/fmtlib/fmt/pull/2924>). Thanks @BRevzin (Barry Revzin) <https://github.com/BRevzin>, @Pokechu22 <https://github.com/Pokechu22>, @setoye (Alta) <https://github.com/setoye>, @rtobar <https://github.com/rtobar>, @rbrugo (Riccardo Brugo) <https://github.com/rbrugo>, @anoonD (cre) <https://github.com/anoonD>, @leha-bot (Alex) <https://github.com/leha-bot>.

  • 👌 Improved build configuration (#2766 <https://github.com/fmtlib/fmt/pull/2766>, #2772 <https://github.com/fmtlib/fmt/pull/2772>, #2836 <https://github.com/fmtlib/fmt/pull/2836>, #2852 <https://github.com/fmtlib/fmt/pull/2852>, #2907 <https://github.com/fmtlib/fmt/pull/2907>, #2913 <https://github.com/fmtlib/fmt/pull/2913>, #2914 <https://github.com/fmtlib/fmt/pull/2914>). Thanks @kambala-decapitator (Andrey Filipenkov) <https://github.com/kambala-decapitator>, @mattiasljungstrom (Mattias Ljungström) <https://github.com/mattiasljungstrom>, @kieselnb (Nick Kiesel) <https://github.com/kieselnb>, @nathannaveen <https://github.com/nathannaveen>, @Vertexwahn <https://github.com/Vertexwahn>.

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

• v8.1.1 Changes

  January 06, 2022

  • ⏪ Restored ABI compatibility with version 8.0.x (#2695 <https://github.com/fmtlib/fmt/issues/2695>, #2696 <https://github.com/fmtlib/fmt/pull/2696>). Thanks @saraedum (Julian Rüth) <https://github.com/saraedum>_.

  • 🛠 Fixed chrono formatting on big endian systems (#2698 <https://github.com/fmtlib/fmt/issues/2698>, #2699 <https://github.com/fmtlib/fmt/pull/2699>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>_ and @xvitaly (Vitaly Zaitsev) <https://github.com/xvitaly>_.

  • 🛠 Fixed a linkage error with mingw (#2691 <https://github.com/fmtlib/fmt/issues/2691>, #2692 <https://github.com/fmtlib/fmt/pull/2692>). Thanks @rbberger (Richard Berger) <https://github.com/rbberger>_.

• v8.1.0 Changes

  January 02, 2022

  • ⚡️ Optimized chrono formatting (#2500 <https://github.com/fmtlib/fmt/pull/2500>, #2537 <https://github.com/fmtlib/fmt/pull/2537>, #2541 <https://github.com/fmtlib/fmt/issues/2541>, #2544 <https://github.com/fmtlib/fmt/pull/2544>, #2550 <https://github.com/fmtlib/fmt/pull/2550>, #2551 <https://github.com/fmtlib/fmt/pull/2551>, #2576 <https://github.com/fmtlib/fmt/pull/2576>, #2577 <https://github.com/fmtlib/fmt/issues/2577>, #2586 <https://github.com/fmtlib/fmt/pull/2586>, #2591 <https://github.com/fmtlib/fmt/pull/2591>, #2594 <https://github.com/fmtlib/fmt/pull/2594>, #2602 <https://github.com/fmtlib/fmt/pull/2602>, #2617 <https://github.com/fmtlib/fmt/pull/2617>, #2628 <https://github.com/fmtlib/fmt/issues/2628>, #2633 <https://github.com/fmtlib/fmt/pull/2633>, #2670 <https://github.com/fmtlib/fmt/issues/2670>, #2671 <https://github.com/fmtlib/fmt/pull/2671>_).

  Processing of some specifiers such as %z and %Y is now up to 10-20 times faster, for example on GCC 11 with libstdc++::

  ----------------------------------------------------------------------------
  Benchmark                                  Before             After
  ----------------------------------------------------------------------------
  FMTFormatter_z                             261 ns             26.3 ns
  FMTFormatterCompile_z                      246 ns             11.6 ns
  FMTFormatter_Y                             263 ns             26.1 ns
  FMTFormatterCompile_Y                      244 ns             10.5 ns
  ----------------------------------------------------------------------------
  

  Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>_ and @toughengineer (Pavel Novikov) <https://github.com/toughengineer>_.

  • Implemented subsecond formatting for chrono durations (#2623 <https://github.com/fmtlib/fmt/pull/2623>). For example (godbolt <https://godbolt.org/z/es7vWTETe>_):

  .. code:: c++

   #include <fmt/chrono.h>
  
   int main() {
     fmt::print("{:%S}", std::chrono::milliseconds(1234));
   }
  

  prints "01.234".

  Thanks @matrackif <https://github.com/matrackif>_.

  • 🛠 Fixed handling of precision 0 when formatting chrono durations (#2587 <https://github.com/fmtlib/fmt/issues/2587>, #2588 <https://github.com/fmtlib/fmt/pull/2588>). Thanks @lukester1975 <https://github.com/lukester1975>_.

  • 🛠 Fixed an overflow on invalid inputs in the tm formatter (#2564 <https://github.com/fmtlib/fmt/pull/2564>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>.

  • ➕ Added fmt::group_digits that formats integers with a non-localized digit separator (comma) for groups of three digits. For example (godbolt <https://godbolt.org/z/TxGxG9Poq>__):

  .. code:: c++

   #include <fmt/format.h>
  
   int main() {
     fmt::print("{} dollars", fmt::group_digits(1000000));
   }
  

  prints "1,000,000 dollars".

  • ➕ Added support for faint, conceal, reverse and blink text styles (#2394 <https://github.com/fmtlib/fmt/pull/2394>_):

  https://user-images.githubusercontent.com/576385/147710227-c68f5317-f8fa-42c3-9123-7c4ba3c398cb.mp4

  Thanks @benit8 (Benoît Lormeau) <https://github.com/benit8>_ and @data-man (Dmitry Atamanov) <https://github.com/data-man>_.

  • ➕ Added experimental support for compile-time floating point formatting (#2426 <https://github.com/fmtlib/fmt/pull/2426>, #2470 <https://github.com/fmtlib/fmt/pull/2470>). It is currently limited to the header-only mode. Thanks @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>_.

  • ➕ Added UDL-based named argument support to compile-time format string checks (#2640 <https://github.com/fmtlib/fmt/issues/2640>, #2649 <https://github.com/fmtlib/fmt/pull/2649>). For example (godbolt <https://godbolt.org/z/ohGbbvonv>__):

  .. code:: c++

   #include <fmt/format.h>
  
   int main() {
     using namespace fmt::literals;
     fmt::print("{answer:s}", "answer"_a=42);
   }
  

  gives a compile-time error on compilers with C++20 consteval and non-type template parameter support (gcc 10+) because s is not a valid format specifier for an integer.

  Thanks @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>_.

  • Implemented escaping of string range elements. For example (godbolt <https://godbolt.org/z/rKvM1vKf3>__):

  .. code:: c++

   #include <fmt/ranges.h>
   #include <vector>
  
   int main() {
     fmt::print("{}", std::vector<std::string>{"\naan"});
   }
  

  is now printed as::

  ["\naan"]
  

  instead of::

  ["
  aan"]
  

  • ➕ Added an experimental ? specifier for escaping strings. (#2674 <https://github.com/fmtlib/fmt/pull/2674>). Thanks @BRevzin (Barry Revzin) <https://github.com/BRevzin>.

  • Switched to JSON-like representation of maps and sets for consistency with Python's str.format. For example (godbolt <https://godbolt.org/z/seKjoY9W5>__):

  .. code:: c++

   #include <fmt/ranges.h>
   #include <map>
  
   int main() {
     fmt::print("{}", std::map<std::string, int>{{"answer", 42}});
   }
  

  is now printed as::

  {"answer": 42}
  

  • 👍 Extended fmt::join to support C++20-only ranges (#2549 <https://github.com/fmtlib/fmt/pull/2549>). Thanks @BRevzin (Barry Revzin) <https://github.com/BRevzin>.

  • ⚡️ Optimized handling of non-const-iterable ranges and implemented initial support for non-const-formattable types.

  • Disabled implicit conversions of scoped enums to integers that was accidentally introduced in earlier versions (#1841 <https://github.com/fmtlib/fmt/pull/1841>_).

  • 🗄 Deprecated implicit conversion of [const] signed char* and [const] unsigned char* to C strings.

  • 🗄 Deprecated _format, a legacy UDL-based format API (#2646 <https://github.com/fmtlib/fmt/pull/2646>). Thanks @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>.

  • Marked format, formatted_size and to_string as [[nodiscard]] (#2612 <https://github.com/fmtlib/fmt/pull/2612>). @0x8000-0000 (Florin Iucha) <https://github.com/0x8000-0000>.

  • ➕ Added missing diagnostic when trying to format function and member pointers as well as objects convertible to pointers which is explicitly disallowed (#2598 <https://github.com/fmtlib/fmt/issues/2598>, #2609 <https://github.com/fmtlib/fmt/pull/2609>, #2610 <https://github.com/fmtlib/fmt/pull/2610>). Thanks @AlexGuteniev (Alex Guteniev) <https://github.com/AlexGuteniev>.

  • Optimized writing to a contiguous buffer with format_to_n (#2489 <https://github.com/fmtlib/fmt/pull/2489>). Thanks @Roman-Koshelev <https://github.com/Roman-Koshelev>.

  • ⚡️ Optimized writing to non-char buffers (#2477 <https://github.com/fmtlib/fmt/pull/2477>). Thanks @Roman-Koshelev <https://github.com/Roman-Koshelev>.

  • Decimal point is now localized when using the L specifier.

  • 👌 Improved floating point formatter implementation (#2498 <https://github.com/fmtlib/fmt/pull/2498>, #2499 <https://github.com/fmtlib/fmt/pull/2499>). Thanks @Roman-Koshelev <https://github.com/Roman-Koshelev>_.

  • 🛠 Fixed handling of very large precision in fixed format (#2616 <https://github.com/fmtlib/fmt/pull/2616>_).

  • Made a table of cached powers used in FP formatting static (#2509 <https://github.com/fmtlib/fmt/pull/2509>). Thanks @jk-jeon (Junekey Jeon) <https://github.com/jk-jeon>.

  • Resolved a lookup ambiguity with C++20 format-related functions due to ADL (#2639 <https://github.com/fmtlib/fmt/issues/2639>, #2641 <https://github.com/fmtlib/fmt/pull/2641>). Thanks @mkurdej (Marek Kurdej) <https://github.com/mkurdej>_.

  • ✂ Removed unnecessary inline namespace qualification (#2642 <https://github.com/fmtlib/fmt/issues/2642>, #2643 <https://github.com/fmtlib/fmt/pull/2643>). Thanks @mkurdej (Marek Kurdej) <https://github.com/mkurdej>_.

  • Implemented argument forwarding in format_to_n (#2462 <https://github.com/fmtlib/fmt/issues/2462>, #2463 <https://github.com/fmtlib/fmt/pull/2463>). Thanks @owent (WenTao Ou) <https://github.com/owent>_.

  • 🛠 Fixed handling of implicit conversions in fmt::to_string and format string compilation (#2565 <https://github.com/fmtlib/fmt/issues/2565>_).

  • 🔄 Changed the default access mode of files created by fmt::output_file to -rw-r--r-- for consistency with fopen (#2530 <https://github.com/fmtlib/fmt/issues/2530>_).

  • 👉 Make fmt::ostream::flush public (#2435 <https://github.com/fmtlib/fmt/issues/2435>_).

  • 👌 Improved C++14/17 attribute detection (#2615 <https://github.com/fmtlib/fmt/pull/2615>). Thanks @AlexGuteniev (Alex Guteniev) <https://github.com/AlexGuteniev>.

  • 👌 Improved consteval detection for MSVC (#2559 <https://github.com/fmtlib/fmt/pull/2559>). Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>.

  • 👌 Improved documentation (#2406 <https://github.com/fmtlib/fmt/issues/2406>, #2446 <https://github.com/fmtlib/fmt/pull/2446>, #2493 <https://github.com/fmtlib/fmt/issues/2493>, #2513 <https://github.com/fmtlib/fmt/issues/2513>, #2515 <https://github.com/fmtlib/fmt/pull/2515>, #2522 <https://github.com/fmtlib/fmt/issues/2522>, #2562 <https://github.com/fmtlib/fmt/pull/2562>, #2575 <https://github.com/fmtlib/fmt/pull/2575>, #2606 <https://github.com/fmtlib/fmt/pull/2606>, #2620 <https://github.com/fmtlib/fmt/pull/2620>, #2676 <https://github.com/fmtlib/fmt/issues/2676>). Thanks @sobolevn (Nikita Sobolev) <https://github.com/sobolevn>, @UnePierre (Max FERGER) <https://github.com/UnePierre>, @zhsj <https://github.com/zhsj>, @phprus (Vladislav Shchapov) <https://github.com/phprus>, @ericcurtin (Eric Curtin) <https://github.com/ericcurtin>, @Lounarok <https://github.com/Lounarok>_.

  • 👌 Improved fuzzers and added a fuzzer for chrono timepoint formatting (#2461 <https://github.com/fmtlib/fmt/pull/2461>, #2469 <https://github.com/fmtlib/fmt/pull/2469>). @pauldreik (Paul Dreik) <https://github.com/pauldreik>_,

  • Added the FMT_SYSTEM_HEADERS CMake option setting which marks {fmt}'s headers as system. It can be used to suppress warnings (#2644 <https://github.com/fmtlib/fmt/issues/2644>, #2651 <https://github.com/fmtlib/fmt/pull/2651>). Thanks @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>_.

  • ➕ Added the Bazel build system support (#2505 <https://github.com/fmtlib/fmt/pull/2505>, #2516 <https://github.com/fmtlib/fmt/pull/2516>). Thanks @Vertexwahn <https://github.com/Vertexwahn>_.

  • 👌 Improved build configuration and tests (#2437 <https://github.com/fmtlib/fmt/issues/2437>, #2558 <https://github.com/fmtlib/fmt/pull/2558>, #2648 <https://github.com/fmtlib/fmt/pull/2648>, #2650 <https://github.com/fmtlib/fmt/pull/2650>, #2663 <https://github.com/fmtlib/fmt/pull/2663>, #2677 <https://github.com/fmtlib/fmt/pull/2677>). Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>, @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>, @phprus (Vladislav Shchapov) <https://github.com/phprus>_.

  • 🛠 Fixed various warnings and compilation issues (#2353 <https://github.com/fmtlib/fmt/pull/2353>, #2356 <https://github.com/fmtlib/fmt/pull/2356>, #2399 <https://github.com/fmtlib/fmt/pull/2399>, #2408 <https://github.com/fmtlib/fmt/issues/2408>, #2414 <https://github.com/fmtlib/fmt/pull/2414>, #2427 <https://github.com/fmtlib/fmt/pull/2427>, #2432 <https://github.com/fmtlib/fmt/pull/2432>, #2442 <https://github.com/fmtlib/fmt/pull/2442>, #2434 <https://github.com/fmtlib/fmt/pull/2434>, #2439 <https://github.com/fmtlib/fmt/issues/2439>, #2447 <https://github.com/fmtlib/fmt/pull/2447>, #2450 <https://github.com/fmtlib/fmt/pull/2450>, #2455 <https://github.com/fmtlib/fmt/issues/2455>, #2465 <https://github.com/fmtlib/fmt/issues/2465>, #2472 <https://github.com/fmtlib/fmt/issues/2472>, #2474 <https://github.com/fmtlib/fmt/issues/2474>, #2476 <https://github.com/fmtlib/fmt/pull/2476>, #2478 <https://github.com/fmtlib/fmt/issues/2478>, #2479 <https://github.com/fmtlib/fmt/issues/2479>, #2481 <https://github.com/fmtlib/fmt/issues/2481>, #2482 <https://github.com/fmtlib/fmt/pull/2482>, #2483 <https://github.com/fmtlib/fmt/pull/2483>, #2490 <https://github.com/fmtlib/fmt/issues/2490>, #2491 <https://github.com/fmtlib/fmt/pull/2491>, #2510 <https://github.com/fmtlib/fmt/pull/2510>, #2518 <https://github.com/fmtlib/fmt/pull/2518>, #2528 <https://github.com/fmtlib/fmt/issues/2528>, #2529 <https://github.com/fmtlib/fmt/pull/2529>, #2539 <https://github.com/fmtlib/fmt/pull/2539>, #2540 <https://github.com/fmtlib/fmt/issues/2540>, #2545 <https://github.com/fmtlib/fmt/pull/2545>, #2555 <https://github.com/fmtlib/fmt/pull/2555>, #2557 <https://github.com/fmtlib/fmt/issues/2557>, #2570 <https://github.com/fmtlib/fmt/issues/2570>, #2573 <https://github.com/fmtlib/fmt/pull/2573>, #2582 <https://github.com/fmtlib/fmt/pull/2582>, #2605 <https://github.com/fmtlib/fmt/issues/2605>, #2611 <https://github.com/fmtlib/fmt/pull/2611>, #2647 <https://github.com/fmtlib/fmt/pull/2647>, #2627 <https://github.com/fmtlib/fmt/issues/2627>, #2630 <https://github.com/fmtlib/fmt/pull/2630>, #2635 <https://github.com/fmtlib/fmt/issues/2635>, #2638 <https://github.com/fmtlib/fmt/issues/2638>, #2653 <https://github.com/fmtlib/fmt/issues/2653>, #2654 <https://github.com/fmtlib/fmt/issues/2654>, #2661 <https://github.com/fmtlib/fmt/issues/2661>, #2664 <https://github.com/fmtlib/fmt/pull/2664>, #2684 <https://github.com/fmtlib/fmt/pull/2684>). Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>, @mwinterb <https://github.com/mwinterb>, @cdacamar (Cameron DaCamara) <https://github.com/cdacamar>, @TrebledJ (Johnathan) <https://github.com/TrebledJ>, @bodomartin (brm) <https://github.com/bodomartin>, @cquammen (Cory Quammen) <https://github.com/cquammen>, @white238 (Chris White) <https://github.com/white238>, @mmarkeloff (Max) <https://github.com/mmarkeloff>, @palacaze (Pierre-Antoine Lacaze) <https://github.com/palacaze>, @jcelerier (Jean-Michaël Celerier) <https://github.com/jcelerier>, @mborn-adi (Mathias Born) <https://github.com/mborn-adi>, @BrukerJWD (Jonathan W) <https://github.com/BrukerJWD>, @spyridon97 (Spiros Tsalikis) <https://github.com/spyridon97>, @phprus (Vladislav Shchapov) <https://github.com/phprus>, @oliverlee (Oliver Lee) <https://github.com/oliverlee>, @joshessman-llnl (Josh Essman) <https://github.com/joshessman-llnl>, @akohlmey (Axel Kohlmeyer) <https://github.com/akohlmey>, @timkalu <https://github.com/timkalu>, @olupton (Olli Lupton) <https://github.com/olupton>, @Acretock <https://github.com/Acretock>, @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>, @andrewcorrigan (Andrew Corrigan) <https://github.com/andrewcorrigan>, @lucpelletier <https://github.com/lucpelletier>, @HazardyKnusperkeks (Björn Schäpers) <https://github.com/HazardyKnusperkeks>.

• v8.0.1 Changes

  July 02, 2021

  • 🛠 Fixed the version number in the inline namespace (#2374 <https://github.com/fmtlib/fmt/issues/2374>_).

  • ➕ Added a missing presentation type check for std::string (#2402 <https://github.com/fmtlib/fmt/issues/2402>_).

  • 🛠 Fixed a linkage error when mixing code built with clang and gcc (#2377 <https://github.com/fmtlib/fmt/issues/2377>_).

  • 🛠 Fixed documentation issues (#2396 <https://github.com/fmtlib/fmt/pull/2396>, #2403 <https://github.com/fmtlib/fmt/issues/2403>, #2406 <https://github.com/fmtlib/fmt/issues/2406>). Thanks @mkurdej (Marek Kurdej) <https://github.com/mkurdej>.

  • ✂ Removed dead code in FP formatter ( #2398 <https://github.com/fmtlib/fmt/pull/2398>). Thanks @javierhonduco (Javier Honduvilla Coto) <https://github.com/javierhonduco>.

  • 🛠 Fixed various warnings and compilation issues (#2351 <https://github.com/fmtlib/fmt/issues/2351>, #2359 <https://github.com/fmtlib/fmt/issues/2359>, #2365 <https://github.com/fmtlib/fmt/pull/2365>, #2368 <https://github.com/fmtlib/fmt/issues/2368>, #2370 <https://github.com/fmtlib/fmt/pull/2370>, #2376 <https://github.com/fmtlib/fmt/pull/2376>, #2381 <https://github.com/fmtlib/fmt/pull/2381>, #2382 <https://github.com/fmtlib/fmt/pull/2382>, #2386 <https://github.com/fmtlib/fmt/issues/2386>, #2389 <https://github.com/fmtlib/fmt/pull/2389>, #2395 <https://github.com/fmtlib/fmt/pull/2395>, #2397 <https://github.com/fmtlib/fmt/pull/2397>, #2400 <https://github.com/fmtlib/fmt/issues/2400>, #2401 <https://github.com/fmtlib/fmt/issues/2401>, #2407 <https://github.com/fmtlib/fmt/pull/2407>). Thanks @zx2c4 (Jason A. Donenfeld) <https://github.com/zx2c4>, @AidanSun05 (Aidan Sun) <https://github.com/AidanSun05>, @mattiasljungstrom (Mattias Ljungström) <https://github.com/mattiasljungstrom>, @joemmett (Jonathan Emmett) <https://github.com/joemmett>, @erengy (Eren Okka) <https://github.com/erengy>, @patlkli (Patrick Geltinger) <https://github.com/patlkli>, @gsjaardema (Greg Sjaardema) <https://github.com/gsjaardema>, @phprus (Vladislav Shchapov) <https://github.com/phprus>_.

• v8.0.0 Changes

  June 21, 2021

  • 0️⃣ Enabled compile-time format string checks by default. For example (godbolt <https://godbolt.org/z/sMxcohGjz>__):

  .. code:: c++

   #include <fmt/core.h>
  
   int main() {
     fmt::print("{:d}", "I am not a number");
   }
  

  gives a compile-time error on compilers with C++20 consteval support (gcc 10+, clang 11+) because d is not a valid format specifier for a string.

  To pass a runtime string wrap it in fmt::runtime:

  .. code:: c++

   fmt::print(fmt::runtime("{:d}"), "I am not a number");
  

  • ➕ Added compile-time formatting (#2019 <https://github.com/fmtlib/fmt/pull/2019>, #2044 <https://github.com/fmtlib/fmt/pull/2044>, #2056 <https://github.com/fmtlib/fmt/pull/2056>, #2072 <https://github.com/fmtlib/fmt/pull/2072>, #2075 <https://github.com/fmtlib/fmt/pull/2075>, #2078 <https://github.com/fmtlib/fmt/issues/2078>, #2129 <https://github.com/fmtlib/fmt/pull/2129>, #2326 <https://github.com/fmtlib/fmt/pull/2326>). For example (godbolt <https://godbolt.org/z/Mxx9d89jM>__):

  .. code:: c++

   #include <fmt/compile.h>
  
   consteval auto compile_time_itoa(int 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_itoa(42);
  

  Most of the formatting functionality is available at compile time with a notable exception of floating-point numbers and pointers. Thanks @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>_.

  • ⚡️ Optimized handling of format specifiers during format string compilation. For example, hexadecimal formatting ("{:x}") is now 3-7x faster than before when using format_to with format string compilation and a stack-allocated buffer (#1944 <https://github.com/fmtlib/fmt/issues/1944>_).

  Before (7.1.3)::

  ----------------------------------------------------------------------------
  Benchmark                                  Time             CPU   Iterations
  ----------------------------------------------------------------------------
  FMTCompileOld/0                         15.5 ns         15.5 ns     43302898
  FMTCompileOld/42                        16.6 ns         16.6 ns     43278267
  FMTCompileOld/273123                    18.7 ns         18.6 ns     37035861
  FMTCompileOld/9223372036854775807       19.4 ns         19.4 ns     35243000
  ----------------------------------------------------------------------------
  

  After (8.x)::

  ----------------------------------------------------------------------------
  Benchmark                                  Time             CPU   Iterations
  ----------------------------------------------------------------------------
  FMTCompileNew/0                         1.99 ns         1.99 ns    360523686
  FMTCompileNew/42                        2.33 ns         2.33 ns    279865664
  FMTCompileNew/273123                    3.72 ns         3.71 ns    190230315
  FMTCompileNew/9223372036854775807       5.28 ns         5.26 ns    130711631
  ----------------------------------------------------------------------------
  

  It is even faster than std::to_chars from libc++ compiled with clang on macOS::

  ----------------------------------------------------------------------------
  Benchmark                                  Time             CPU   Iterations
  ----------------------------------------------------------------------------
  ToChars/0                               4.42 ns         4.41 ns    160196630
  ToChars/42                              5.00 ns         4.98 ns    140735201
  ToChars/273123                          7.26 ns         7.24 ns     95784130
  ToChars/9223372036854775807             8.77 ns         8.75 ns     75872534
  ----------------------------------------------------------------------------
  

  In other cases, especially involving std::string construction, the speed up is usually lower because handling format specifiers takes a smaller fraction of the total time.

  • ➕ Added the _cf user-defined literal to represent a compiled format string. It can be used instead of the FMT_COMPILE macro (#2043 <https://github.com/fmtlib/fmt/pull/2043>, #2242 <https://github.com/fmtlib/fmt/pull/2242>):

  .. code:: c++

   #include <fmt/compile.h>
  
   using namespace fmt::literals;
   auto s = fmt::format(FMT_COMPILE("{}"), 42); // 🙁 not modern
   auto s = fmt::format("{}"_cf, 42);           // 🙂 modern as hell
  

  It requires compiler support for class types in non-type template parameters (a C++20 feature) which is available in GCC 9.3+. Thanks @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>_.

  • Format string compilation now requires format functions of formatter specializations for user-defined types to be const:

  .. code:: c++

   template <> struct fmt::formatter<my_type>: formatter<string_view> {
     template <typename FormatContext>
     auto format(my_type obj, FormatContext& ctx) const {  // Note const here.
       // ...
     }
   };
  

  • ➕ Added UDL-based named argument support to format string compilation (#2243 <https://github.com/fmtlib/fmt/pull/2243>, #2281 <https://github.com/fmtlib/fmt/pull/2281>). For example:

  .. code:: c++

   #include <fmt/compile.h>
  
   using namespace fmt::literals;
   auto s = fmt::format(FMT_COMPILE("{answer}"), "answer"_a = 42);
  

  Here the argument named "answer" is resolved at compile time with no runtime overhead. Thanks @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>_.

  • ➕ Added format string compilation support to fmt::print (#2280 <https://github.com/fmtlib/fmt/issues/2280>, #2304 <https://github.com/fmtlib/fmt/pull/2304>). Thanks @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>_.

  • ➕ Added initial support for compiling {fmt} as a C++20 module (#2235 <https://github.com/fmtlib/fmt/pull/2235>, #2240 <https://github.com/fmtlib/fmt/pull/2240>, #2260 <https://github.com/fmtlib/fmt/pull/2260>, #2282 <https://github.com/fmtlib/fmt/pull/2282>, #2283 <https://github.com/fmtlib/fmt/pull/2283>, #2288 <https://github.com/fmtlib/fmt/pull/2288>, #2298 <https://github.com/fmtlib/fmt/pull/2298>, #2306 <https://github.com/fmtlib/fmt/pull/2306>, #2307 <https://github.com/fmtlib/fmt/pull/2307>, #2309 <https://github.com/fmtlib/fmt/pull/2309>, #2318 <https://github.com/fmtlib/fmt/pull/2318>, #2324 <https://github.com/fmtlib/fmt/pull/2324>, #2332 <https://github.com/fmtlib/fmt/pull/2332>, #2340 <https://github.com/fmtlib/fmt/pull/2340>). Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>_.

  • 0️⃣ Made symbols private by default reducing shared library size (#2301 <https://github.com/fmtlib/fmt/pull/2301>). For example there was a ~15% reported reduction on one platform. Thanks @sergiud (Sergiu Deitsch) <https://github.com/sergiud>.

  • ⚡️ Optimized includes making the result of preprocessing fmt/format.h ~20% smaller with libstdc++/C++20 and slightly improving build times (#1998 <https://github.com/fmtlib/fmt/issues/1998>_).

  • ➕ Added support of ranges with non-const begin / end (#1953 <https://github.com/fmtlib/fmt/pull/1953>). Thanks @kitegi (sarah) <https://github.com/kitegi>.

  • ➕ Added support of std::byte and other formattable types to fmt::join (#1981 <https://github.com/fmtlib/fmt/issues/1981>, #2040 <https://github.com/fmtlib/fmt/issues/2040>, #2050 <https://github.com/fmtlib/fmt/pull/2050>, #2262 <https://github.com/fmtlib/fmt/issues/2262>). For example:

  .. code:: c++

   #include <fmt/format.h>
   #include <cstddef>
   #include <vector>
  
   int main() {
     auto bytes = std::vector{std::byte(4), std::byte(2)};
     fmt::print("{}", fmt::join(bytes, ""));
   }
  

  prints "42".

  Thanks @kamibo (Camille Bordignon) <https://github.com/kamibo>_.

  • 0️⃣ Implemented the default format for std::chrono::system_clock (#2319 <https://github.com/fmtlib/fmt/issues/2319>, #2345 <https://github.com/fmtlib/fmt/pull/2345>). For example:

  .. code:: c++

   #include <fmt/chrono.h>
  
   int main() {
     fmt::print("{}", std::chrono::system_clock::now());
   }
  

  prints "2021-06-18 15:22:00" (the output depends on the current date and time). Thanks @sunmy2019 <https://github.com/sunmy2019>_.

  • 0️⃣ Made more chrono specifiers locale independent by default. Use the 'L' specifier to get localized formatting. For example:

  .. code:: c++

   #include <fmt/chrono.h>
  
   int main() {
     std::locale::global(std::locale("ru_RU.UTF-8"));
     auto monday = std::chrono::weekday(1);
     fmt::print("{}\n", monday);   // prints "Mon"
     fmt::print("{:L}\n", monday); // prints "пн"
   }
  

  • 👌 Improved locale handling in chrono formatting (#2337 <https://github.com/fmtlib/fmt/issues/2337>, #2349 <https://github.com/fmtlib/fmt/pull/2349>, #2350 <https://github.com/fmtlib/fmt/pull/2350>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>.

  • 🗄 Deprecated fmt/locale.h moving the formatting functions that take a locale to fmt/format.h (char) and fmt/xchar (other overloads). This doesn't introduce a dependency on <locale> so there is virtually no compile time effect.

  • 🗄 Deprecated an undocumented format_to overload that takes basic_memory_buffer.

  • Made parameter order in vformat_to consistent with format_to (#2327 <https://github.com/fmtlib/fmt/issues/2327>_).

  • ➕ Added support for time points with arbitrary durations (#2208 <https://github.com/fmtlib/fmt/issues/2208>_). For example:

  .. code:: c++

   #include <fmt/chrono.h>
  
   int main() {
     using tp = std::chrono::time_point<
       std::chrono::system_clock, std::chrono::seconds>;
     fmt::print("{:%S}", tp(std::chrono::seconds(42)));
   }
  

  prints "42".

  • 0️⃣ Formatting floating-point numbers no longer produces trailing zeros by default for consistency with std::format. For example:

  .. code:: c++

   #include <fmt/core.h>
  
   int main() {
     fmt::print("{0:.3}", 1.1);
   }
  

  prints "1.1". Use the '#' specifier to keep trailing zeros.

  • ⬇️ Dropped a limit on the number of elements in a range and replaced {} with [] as range delimiters for consistency with Python's str.format.

  • The 'L' specifier for locale-specific numeric formatting can now be combined with presentation specifiers as in std::format. For example:

  .. code:: c++

   #include <fmt/core.h>
   #include <locale>
  
   int main() {
     std::locale::global(std::locale("fr_FR.UTF-8"));
     fmt::print("{0:.2Lf}", 0.42);
   }
  

  prints "0,42". The deprecated 'n' specifier has been removed.

  • Made the 0 specifier ignored for infinity and NaN (#2305 <https://github.com/fmtlib/fmt/issues/2305>, #2310 <https://github.com/fmtlib/fmt/pull/2310>). Thanks @Liedtke (Matthias Liedtke) <https://github.com/Liedtke>_.

  • 0️⃣ Made the hexfloat formatting use the right alignment by default (#2308 <https://github.com/fmtlib/fmt/issues/2308>, #2317 <https://github.com/fmtlib/fmt/pull/2317>). Thanks @Liedtke (Matthias Liedtke) <https://github.com/Liedtke>_.

  • ✂ Removed the deprecated numeric alignment ('='). Use the '0' specifier instead.

  • ✂ Removed the deprecated fmt/posix.h header that has been replaced with fmt/os.h.

  • Removed the deprecated format_to_n_context, format_to_n_args and make_format_to_n_args. They have been replaced with format_context, format_args` andmake_format_args`` respectively.

  • 🚚 Moved wchar_t-specific functions and types to fmt/xchar.h. You can define FMT_DEPRECATED_INCLUDE_XCHAR to automatically include fmt/xchar.h from fmt/format.h but this will be disabled in the next major release.

  • 🛠 Fixed handling of the '+' specifier in localized formatting (#2133 <https://github.com/fmtlib/fmt/issues/2133>_).

  • ➕ Added support for the 's' format specifier that gives textual representation of bool (#2094 <https://github.com/fmtlib/fmt/issues/2094>, #2109 <https://github.com/fmtlib/fmt/pull/2109>). For example:

  .. code:: c++

   #include <fmt/core.h>
  
   int main() {
     fmt::print("{:s}", true);
   }
  

  prints "true". Thanks @powercoderlol (Ivan Polyakov) <https://github.com/powercoderlol>_.

  • Made fmt::ptr work with function pointers (#2131 <https://github.com/fmtlib/fmt/pull/2131>_). For example:

  .. code:: c++

   #include <fmt/format.h>
  
   int main() {
     fmt::print("My main: {}\n", fmt::ptr(main));
   }
  

  Thanks @mikecrowe (Mike Crowe) <https://github.com/mikecrowe>_.

  • 👍 The undocumented support for specializing formatter for pointer types has been removed.

  • 🛠 Fixed fmt::formatted_size with format string compilation (#2141 <https://github.com/fmtlib/fmt/pull/2141>, #2161 <https://github.com/fmtlib/fmt/pull/2161>). Thanks @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>_.

  • 🛠 Fixed handling of empty format strings during format string compilation (#2042 <https://github.com/fmtlib/fmt/issues/2042>_):

  .. code:: c++

   auto s = fmt::format(FMT_COMPILE(""));
  

  Thanks @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>_.

  • 🛠 Fixed handling of enums in fmt::to_string (#2036 <https://github.com/fmtlib/fmt/issues/2036>_).

  • 👌 Improved width computation (#2033 <https://github.com/fmtlib/fmt/issues/2033>, #2091 <https://github.com/fmtlib/fmt/issues/2091>). For example:

  .. code:: c++

   #include <fmt/core.h>
  
   int main() {
     fmt::print("{:-<10}{}\n", "你好", "世界");
     fmt::print("{:-<10}{}\n", "hello", "world");
   }
  

  prints

  .. image:: https://user-images.githubusercontent.com/576385/ 119840373-cea3ca80-beb9-11eb-91e0-54266c48e181.png

  on a modern terminal.

  • The experimental fast output stream (fmt::ostream) is now truncated by default for consistency with fopen (#2018 <https://github.com/fmtlib/fmt/issues/2018>_). For example:

  .. code:: c++

   #include <fmt/os.h>
  
   int main() {
     fmt::ostream out1 = fmt::output_file("guide");
     out1.print("Zaphod");
     out1.close();
     fmt::ostream out2 = fmt::output_file("guide");
     out2.print("Ford");
   }
  

  writes "Ford" to the file "guide". To preserve the old file content if any pass fmt::file::WRONLY | fmt::file::CREATE flags to fmt::output_file.

  • 🛠 Fixed moving of fmt::ostream that holds buffered data (#2197 <https://github.com/fmtlib/fmt/issues/2197>, #2198 <https://github.com/fmtlib/fmt/pull/2198>). Thanks @vtta <https://github.com/vtta>_.

  • 👻 Replaced the fmt::system_error exception with a function of the same name that constructs std::system_error (#2266 <https://github.com/fmtlib/fmt/issues/2266>_).

  • 🏁 Replaced the fmt::windows_error exception with a function of the same name that constructs std::system_error with the category returned by fmt::system_category() (#2274 <https://github.com/fmtlib/fmt/issues/2274>, #2275 <https://github.com/fmtlib/fmt/pull/2275>). The latter is similar to std::sytem_category but correctly handles UTF-8. Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>_.

  • Replaced fmt::error_code with std::error_code and made it formattable (#2269 <https://github.com/fmtlib/fmt/issues/2269>, #2270 <https://github.com/fmtlib/fmt/pull/2270>, #2273 <https://github.com/fmtlib/fmt/pull/2273>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>.

  • ➕ Added speech synthesis support (#2206 <https://github.com/fmtlib/fmt/pull/2206>_).

  • Made format_to work with a memory buffer that has a custom allocator (#2300 <https://github.com/fmtlib/fmt/pull/2300>). Thanks @voxmea <https://github.com/voxmea>.

  • 👍 Added Allocator::max_size support to basic_memory_buffer. (#1960 <https://github.com/fmtlib/fmt/pull/1960>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>.

  • ➕ Added wide string support to fmt::join (#2236 <https://github.com/fmtlib/fmt/pull/2236>). Thanks @crbrz <https://github.com/crbrz>.

  • Made iterators passed to formatter specializations via a format context satisfy C++20 std::output_iterator requirements (#2156 <https://github.com/fmtlib/fmt/issues/2156>, #2158 <https://github.com/fmtlib/fmt/pull/2158>, #2195 <https://github.com/fmtlib/fmt/issues/2195>, #2204 <https://github.com/fmtlib/fmt/pull/2204>). Thanks @randomnetcat (Jason Cobb) <https://github.com/randomnetcat>_.

  • ⚡️ Optimized the printf implementation (#1982 <https://github.com/fmtlib/fmt/pull/1982>, #1984 <https://github.com/fmtlib/fmt/pull/1984>, #2016 <https://github.com/fmtlib/fmt/pull/2016>, #2164 <https://github.com/fmtlib/fmt/pull/2164>). Thanks @rimathia <https://github.com/rimathia>_ and @moiwi <https://github.com/moiwi>_.

  • 👌 Improved detection of constexpr char_traits (#2246 <https://github.com/fmtlib/fmt/pull/2246>, #2257 <https://github.com/fmtlib/fmt/pull/2257>). Thanks @phprus (Vladislav Shchapov) <https://github.com/phprus>_.

  • 🛠 Fixed writing to stdout when it is redirected to NUL on Windows (#2080 <https://github.com/fmtlib/fmt/issues/2080>_).

  • 🛠 Fixed exception propagation from iterators (#2097 <https://github.com/fmtlib/fmt/issues/2097>_).

  • 👌 Improved strftime error handling (#2238 <https://github.com/fmtlib/fmt/issues/2238>, #2244 <https://github.com/fmtlib/fmt/pull/2244>). Thanks @yumeyao <https://github.com/yumeyao>_.

  • 🗄 Stopped using deprecated GCC UDL template extension.

  • ➕ Added fmt/args.h to the install target (#2096 <https://github.com/fmtlib/fmt/issues/2096>_).

  • Error messages are now passed to assert when exceptions are disabled (#2145 <https://github.com/fmtlib/fmt/pull/2145>). Thanks @NobodyXu (Jiahao XU) <https://github.com/NobodyXu>.

  • Added the FMT_MASTER_PROJECT CMake option to control build and install targets when {fmt} is included via add_subdirectory (#2098 <https://github.com/fmtlib/fmt/issues/2098>, #2100 <https://github.com/fmtlib/fmt/pull/2100>). Thanks @randomizedthinking <https://github.com/randomizedthinking>_.

  • 👌 Improved build configuration (#2026 <https://github.com/fmtlib/fmt/pull/2026>, #2122 <https://github.com/fmtlib/fmt/pull/2122>). Thanks @luncliff (Park DongHa) <https://github.com/luncliff>_ and @ibaned (Dan Ibanez) <https://github.com/ibaned>_.

  • 🛠 Fixed various warnings and compilation issues (#1947 <https://github.com/fmtlib/fmt/issues/1947>, #1959 <https://github.com/fmtlib/fmt/pull/1959>, #1963 <https://github.com/fmtlib/fmt/pull/1963>, #1965 <https://github.com/fmtlib/fmt/pull/1965>, #1966 <https://github.com/fmtlib/fmt/issues/1966>, #1974 <https://github.com/fmtlib/fmt/pull/1974>, #1975 <https://github.com/fmtlib/fmt/pull/1975>, #1990 <https://github.com/fmtlib/fmt/pull/1990>, #2000 <https://github.com/fmtlib/fmt/issues/2000>, #2001 <https://github.com/fmtlib/fmt/pull/2001>, #2002 <https://github.com/fmtlib/fmt/issues/2002>, #2004 <https://github.com/fmtlib/fmt/issues/2004>, #2006 <https://github.com/fmtlib/fmt/pull/2006>, #2009 <https://github.com/fmtlib/fmt/pull/2009>, #2010 <https://github.com/fmtlib/fmt/pull/2010>, #2038 <https://github.com/fmtlib/fmt/issues/2038>, #2039 <https://github.com/fmtlib/fmt/issues/2039>, #2047 <https://github.com/fmtlib/fmt/issues/2047>, #2053 <https://github.com/fmtlib/fmt/pull/2053>, #2059 <https://github.com/fmtlib/fmt/issues/2059>, #2065 <https://github.com/fmtlib/fmt/pull/2065>, #2067 <https://github.com/fmtlib/fmt/pull/2067>, #2068 <https://github.com/fmtlib/fmt/pull/2068>, #2073 <https://github.com/fmtlib/fmt/pull/2073>, #2103 <https://github.com/fmtlib/fmt/issues/2103>, #2105 <https://github.com/fmtlib/fmt/issues/2105>, #2106 <https://github.com/fmtlib/fmt/pull/2106>, #2107 <https://github.com/fmtlib/fmt/pull/2107>, #2116 <https://github.com/fmtlib/fmt/issues/2116>, #2117 <https://github.com/fmtlib/fmt/pull/2117>, #2118 <https://github.com/fmtlib/fmt/issues/2118>, #2119 <https://github.com/fmtlib/fmt/pull/2119>, #2127 <https://github.com/fmtlib/fmt/issues/2127>, #2128 <https://github.com/fmtlib/fmt/pull/2128>, #2140 <https://github.com/fmtlib/fmt/issues/2140>, #2142 <https://github.com/fmtlib/fmt/issues/2142>, #2143 <https://github.com/fmtlib/fmt/pull/2143>, #2144 <https://github.com/fmtlib/fmt/pull/2144>, #2147 <https://github.com/fmtlib/fmt/issues/2147>, #2148 <https://github.com/fmtlib/fmt/issues/2148>, #2149 <https://github.com/fmtlib/fmt/issues/2149>, #2152 <https://github.com/fmtlib/fmt/pull/2152>, #2160 <https://github.com/fmtlib/fmt/pull/2160>, #2170 <https://github.com/fmtlib/fmt/issues/2170>, #2175 <https://github.com/fmtlib/fmt/issues/2175>, #2176 <https://github.com/fmtlib/fmt/issues/2176>, #2177 <https://github.com/fmtlib/fmt/pull/2177>, #2178 <https://github.com/fmtlib/fmt/issues/2178>, #2179 <https://github.com/fmtlib/fmt/pull/2179>, #2180 <https://github.com/fmtlib/fmt/issues/2180>, #2181 <https://github.com/fmtlib/fmt/issues/2181>, #2183 <https://github.com/fmtlib/fmt/pull/2183>, #2184 <https://github.com/fmtlib/fmt/issues/2184>, #2185 <https://github.com/fmtlib/fmt/issues/2185>, #2186 <https://github.com/fmtlib/fmt/pull/2186>, #2187 <https://github.com/fmtlib/fmt/pull/2187>, #2190 <https://github.com/fmtlib/fmt/pull/2190>, #2192 <https://github.com/fmtlib/fmt/pull/2192>, #2194 <https://github.com/fmtlib/fmt/pull/2194>, #2205 <https://github.com/fmtlib/fmt/pull/2205>, #2210 <https://github.com/fmtlib/fmt/issues/2210>, #2211 <https://github.com/fmtlib/fmt/pull/2211>, #2215 <https://github.com/fmtlib/fmt/pull/2215>, #2216 <https://github.com/fmtlib/fmt/pull/2216>, #2218 <https://github.com/fmtlib/fmt/pull/2218>, #2220 <https://github.com/fmtlib/fmt/pull/2220>, #2228 <https://github.com/fmtlib/fmt/issues/2228>, #2229 <https://github.com/fmtlib/fmt/pull/2229>, #2230 <https://github.com/fmtlib/fmt/pull/2230>, #2233 <https://github.com/fmtlib/fmt/issues/2233>, #2239 <https://github.com/fmtlib/fmt/pull/2239>, #2248 <https://github.com/fmtlib/fmt/issues/2248>, #2252 <https://github.com/fmtlib/fmt/issues/2252>, #2253 <https://github.com/fmtlib/fmt/pull/2253>, #2255 <https://github.com/fmtlib/fmt/pull/2255>, #2261 <https://github.com/fmtlib/fmt/issues/2261>, #2278 <https://github.com/fmtlib/fmt/issues/2278>, #2284 <https://github.com/fmtlib/fmt/issues/2284>, #2287 <https://github.com/fmtlib/fmt/pull/2287>, #2289 <https://github.com/fmtlib/fmt/pull/2289>, #2290 <https://github.com/fmtlib/fmt/pull/2290>, #2293 <https://github.com/fmtlib/fmt/pull/2293>, #2295 <https://github.com/fmtlib/fmt/issues/2295>, #2296 <https://github.com/fmtlib/fmt/pull/2296>, #2297 <https://github.com/fmtlib/fmt/pull/2297>, #2311 <https://github.com/fmtlib/fmt/issues/2311>, #2313 <https://github.com/fmtlib/fmt/pull/2313>, #2315 <https://github.com/fmtlib/fmt/pull/2315>, #2320 <https://github.com/fmtlib/fmt/issues/2320>, #2321 <https://github.com/fmtlib/fmt/pull/2321>, #2323 <https://github.com/fmtlib/fmt/pull/2323>, #2328 <https://github.com/fmtlib/fmt/issues/2328>, #2329 <https://github.com/fmtlib/fmt/pull/2329>, #2333 <https://github.com/fmtlib/fmt/pull/2333>, #2338 <https://github.com/fmtlib/fmt/pull/2338>, #2341 <https://github.com/fmtlib/fmt/pull/2341>). Thanks @darklukee <https://github.com/darklukee>, @fagg (Ashton Fagg) <https://github.com/fagg>, @killerbot242 (Lieven de Cock) <https://github.com/killerbot242>, @jgopel (Jonathan Gopel) <https://github.com/jgopel>, @yeswalrus (Walter Gray) <https://github.com/yeswalrus>, @Finkman <https://github.com/Finkman>, @HazardyKnusperkeks (Björn Schäpers) <https://github.com/HazardyKnusperkeks>, @dkavolis (Daumantas Kavolis) <https://github.com/dkavolis>, @concatime (Issam Maghni) <https://github.com/concatime>, @chronoxor (Ivan Shynkarenka) <https://github.com/chronoxor>, @summivox (Yin Zhong) <https://github.com/summivox>, @yNeo <https://github.com/yNeo>, @Apache-HB (Elliot) <https://github.com/Apache-HB>, @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>, @toojays (John Steele Scott) <https://github.com/toojays>, @Brainy0207 <https://github.com/Brainy0207>, @vadz (VZ) <https://github.com/vadz>, @imsherlock (Ryan Sherlock) <https://github.com/imsherlock>, @phprus (Vladislav Shchapov) <https://github.com/phprus>, @white238 (Chris White) <https://github.com/white238>, @yafshar (Yaser Afshar) <https://github.com/yafshar>, @BillyDonahue (Billy Donahue) <https://github.com/BillyDonahue>, @jstaahl <https://github.com/jstaahl>, @denchat <https://github.com/denchat>, @DanielaE (Daniela Engert) <https://github.com/DanielaE>, @ilyakurdyukov (Ilya Kurdyukov) <https://github.com/ilyakurdyukov>, @ilmai <https://github.com/ilmai>, @JessyDL (Jessy De Lannoit) <https://github.com/JessyDL>, @sergiud (Sergiu Deitsch) <https://github.com/sergiud>, @mwinterb <https://github.com/mwinterb>, @sven-herrmann <https://github.com/sven-herrmann>, @jmelas (John Melas) <https://github.com/jmelas>, @twoixter (Jose Miguel Pérez) <https://github.com/twoixter>, @crbrz <https://github.com/crbrz>, @upsj (Tobias Ribizel) <https://github.com/upsj>_.

  • 👌 Improved documentation (#1986 <https://github.com/fmtlib/fmt/issues/1986>, #2051 <https://github.com/fmtlib/fmt/pull/2051>, #2057 <https://github.com/fmtlib/fmt/issues/2057>, #2081 <https://github.com/fmtlib/fmt/pull/2081>, #2084 <https://github.com/fmtlib/fmt/issues/2084>, #2312 <https://github.com/fmtlib/fmt/pull/2312>). Thanks @imba-tjd (谭九鼎) <https://github.com/imba-tjd>, @0x416c69 (AlιAѕѕaѕѕιN) <https://github.com/0x416c69>, @mordante <https://github.com/mordante>_.

  • ✅ Continuous integration and test improvements (#1969 <https://github.com/fmtlib/fmt/issues/1969>, #1991 <https://github.com/fmtlib/fmt/pull/1991>, #2020 <https://github.com/fmtlib/fmt/pull/2020>, #2110 <https://github.com/fmtlib/fmt/pull/2110>, #2114 <https://github.com/fmtlib/fmt/pull/2114>, #2196 <https://github.com/fmtlib/fmt/issues/2196>, #2217 <https://github.com/fmtlib/fmt/pull/2217>, #2247 <https://github.com/fmtlib/fmt/pull/2247>, #2256 <https://github.com/fmtlib/fmt/pull/2256>, #2336 <https://github.com/fmtlib/fmt/pull/2336>, #2346 <https://github.com/fmtlib/fmt/pull/2346>). Thanks @jgopel (Jonathan Gopel) <https://github.com/jgopel>, @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>_ and @DanielaE (Daniela Engert) <https://github.com/DanielaE>_.

• v7.1.3 Changes

  November 25, 2020

  • Fixed handling of buffer boundaries in format_to_n (#1996 <https://github.com/fmtlib/fmt/issues/1996>, #2029 <https://github.com/fmtlib/fmt/issues/2029>).

  • 🛠 Fixed linkage errors when linking with a shared library (#2011 <https://github.com/fmtlib/fmt/issues/2011>_).

  • 👍 Reintroduced ostream support to range formatters (#2014 <https://github.com/fmtlib/fmt/issues/2014>_).

  • Worked around an issue with mixing std versions in gcc (#2017 <https://github.com/fmtlib/fmt/issues/2017>_).

• v7.1.2 Changes

  November 04, 2020

  • 🛠 Fixed floating point formatting with large precision (#1976 <https://github.com/fmtlib/fmt/issues/1976>_).

• v7.1.1 Changes

  November 02, 2020

  • 🛠 Fixed ABI compatibility with 7.0.x (#1961 <https://github.com/fmtlib/fmt/issues/1961>_).

  • Added the FMT_ARM_ABI_COMPATIBILITY macro to work around ABI incompatibility between GCC and Clang on ARM (#1919 <https://github.com/fmtlib/fmt/issues/1919>_).

  • Worked around a SFINAE bug in GCC 8 (#1957 <https://github.com/fmtlib/fmt/issues/1957>_).

  • 🛠 Fixed linkage errors when building with GCC's LTO (#1955 <https://github.com/fmtlib/fmt/issues/1955>_).

  • Fixed a compilation error when building without __builtin_clz or equivalent (#1968 <https://github.com/fmtlib/fmt/pull/1968>). Thanks @tohammer (Tobias Hammer) <https://github.com/tohammer>.

  • 🛠 Fixed a sign conversion warning (#1964 <https://github.com/fmtlib/fmt/pull/1964>). Thanks @OptoCloud <https://github.com/OptoCloud>.

• v7.1.0 Changes

  October 26, 2020

  • Switched from Grisu3 <https://www.cs.tufts.edu/~nr/cs257/archive/florian-loitsch/printf.pdf>_ to Dragonbox <https://github.com/jk-jeon/dragonbox>_ for the default floating-point formatting which gives the shortest decimal representation with round-trip guarantee and correct rounding (#1882 <https://github.com/fmtlib/fmt/pull/1882>, #1887 <https://github.com/fmtlib/fmt/pull/1887>, #1894 <https://github.com/fmtlib/fmt/pull/1894>). This makes {fmt} up to 20-30x faster than common implementations of std::ostringstream and sprintf on dtoa-benchmark <https://github.com/fmtlib/dtoa-benchmark> and faster than double-conversion and Ryū:

  .. image:: https://user-images.githubusercontent.com/576385/ 95684665-11719600-0ba8-11eb-8e5b-972ff4e49428.png

  It is possible to get even better performance at the cost of larger binary size by compiling with the FMT_USE_FULL_CACHE_DRAGONBOX macro set to 1.

  Thanks @jk-jeon (Junekey Jeon) <https://github.com/jk-jeon>_.

  • ➕ Added an experimental unsynchronized file output API which, together with format string compilation <https://fmt.dev/latest/api.html#compile-api>, can give 5-9 times speed up compared to fprintf <https://www.zverovich.net/2020/08/04/optimal-file-buffer-size.html> on common platforms (godbolt <https://godbolt.org/z/nsTcG8>__):

  .. code:: c++

   #include <fmt/os.h>
  
   int main() {
     auto f = fmt::output_file("guide");
     f.print("The answer is {}.", 42);
   }
  

  • Added a formatter for std::chrono::time_point<system_clock> (#1819 <https://github.com/fmtlib/fmt/issues/1819>, #1837 <https://github.com/fmtlib/fmt/pull/1837>). For example (godbolt <https://godbolt.org/z/c4M6fh>__):

  .. code:: c++

   #include <fmt/chrono.h>
  
   int main() {
     auto now = std::chrono::system_clock::now();
     fmt::print("The time is {:%H:%M:%S}.\n", now);
   }
  

  Thanks @adamburgess (Adam Burgess) <https://github.com/adamburgess>_.

  • ➕ Added support for ranges with non-const begin/end to fmt::join (#1784 <https://github.com/fmtlib/fmt/issues/1784>, #1786 <https://github.com/fmtlib/fmt/pull/1786>). For example (godbolt <https://godbolt.org/z/jP63Tv>__):

  .. code:: c++

   #include <fmt/ranges.h>
   #include <range/v3/view/filter.hpp>
  
   int main() {
     using std::literals::string_literals::operator""s;
     auto strs = std::array{"a"s, "bb"s, "ccc"s};
     auto range = strs | ranges::views::filter(
       [] (const std::string &x) { return x.size() != 2; }
     );
     fmt::print("{}\n", fmt::join(range, ""));
   }
  

  prints "accc".

  Thanks @tonyelewis (Tony E Lewis) <https://github.com/tonyelewis>_.

  • ➕ Added a memory_buffer::append overload that takes a range (#1806 <https://github.com/fmtlib/fmt/pull/1806>). Thanks @BRevzin (Barry Revzin) <https://github.com/BRevzin>.

  • 👌 Improved handling of single code units in FMT_COMPILE. For example:

  .. code:: c++

   #include <fmt/compile.h>
  
   char* f(char* buf) {
     return fmt::format_to(buf, FMT_COMPILE("x{}"), 42);
   }
  

  compiles to just (godbolt <https://godbolt.org/z/5vncz3>__):

  .. code:: asm

   _Z1fPc:
     movb $120, (%rdi)
     xorl %edx, %edx
     cmpl $42, _ZN3fmt2v76detail10basic_dataIvE23zero_or_powers_of_10_32E+8(%rip)
     movl $3, %eax
     seta %dl
     subl %edx, %eax
     movzwl _ZN3fmt2v76detail10basic_dataIvE6digitsE+84(%rip), %edx
     cltq
     addq %rdi, %rax
     movw %dx, -2(%rax)
     ret
  

  Here a single mov instruction writes 'x' ($120) to the output buffer.

  • ➕ Added dynamic width support to format string compilation (#1809 <https://github.com/fmtlib/fmt/issues/1809>_).

  • 👌 Improved error reporting for unformattable types: now you'll get the type name directly in the error message instead of the note:

  .. code:: c++

   #include <fmt/core.h>
  
   struct how_about_no {};
  
   int main() {
     fmt::print("{}", how_about_no());
   }
  

  Error (godbolt <https://godbolt.org/z/GoxM4e>__):

  fmt/core.h:1438:3: error: static_assert failed due to requirement 'fmt::v7::formattable<how_about_no>()' "Cannot format an argument. To make type T formattable provide a formatter<T> specialization: https://fmt.dev/latest/api.html#udt" ...

  • Added the make_args_checked <https://fmt.dev/7.1.0/api.html#argument-lists>_ function template that allows you to write formatting functions with compile-time format string checks and avoid binary code bloat (godbolt <https://godbolt.org/z/PEf9qr>__):

  .. code:: c++

   void vlog(const char* file, int line, fmt::string_view format,
             fmt::format_args args) {
     fmt::print("{}: {}: ", file, line);
     fmt::vprint(format, args);
   }
  
   template <typename S, typename... Args>
   void log(const char* file, int line, const S& format, Args&&... args) {
     vlog(file, line, format,
         fmt::make_args_checked<Args...>(format, args...));
   }
  
   #define MY_LOG(format, ...) \
     log(__FILE__, __LINE__, FMT_STRING(format), __VA_ARGS__)
  
   MY_LOG("invalid squishiness: {}", 42);
  

  • 🖨 Replaced snprintf fallback with a faster internal IEEE 754 float and double formatter for arbitrary precision. For example (godbolt <https://godbolt.org/z/dPhWvj>__):

  .. code:: c++

   #include <fmt/core.h>
  
   int main() {
     fmt::print("{:.500}\n", 4.9406564584124654E-324);
   }
  

  prints

  4.9406564584124654417656879286822137236505980261432476442558568250067550727020875186529983636163599237979656469544571773092665671035593979639877479601078187812630071319031140452784581716784898210368871863605699873072305000638740915356498438731247339727316961514003171538539807412623856559117102665855668676818703956031062493194527159149245532930545654440112748012970999954193198940908041656332452475714786901472678015935523861155013480352649347201937902681071074917033322268447533357208324319360923829e-324.

  • Made format_to_n and formatted_size part of the core API <https://fmt.dev/latest/api.html#core-api>__ (godbolt <https://godbolt.org/z/sPjY1K>__):

  .. code:: c++

   #include <fmt/core.h>
  
   int main() {
     char buffer[10];
     auto result = fmt::format_to_n(buffer, sizeof(buffer), "{}", 42);
   }
  

  • Added fmt::format_to_n overload with format string compilation (#1764 <https://github.com/fmtlib/fmt/issues/1764>, #1767 <https://github.com/fmtlib/fmt/pull/1767>, #1869 <https://github.com/fmtlib/fmt/pull/1869>). For example (godbolt <https://godbolt.org/z/93h86q>_):

  .. code:: c++

   #include <fmt/compile.h>
  
   int main() {
     char buffer[8];
     fmt::format_to_n(buffer, sizeof(buffer), FMT_COMPILE("{}"), 42);
   }
  

  Thanks @Kurkin (Dmitry Kurkin) <https://github.com/Kurkin>, @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>.

  • Added fmt::format_to overload that take text_style (#1593 <https://github.com/fmtlib/fmt/issues/1593>, #1842 <https://github.com/fmtlib/fmt/issues/1842>, #1843 <https://github.com/fmtlib/fmt/pull/1843>). For example (godbolt <https://godbolt.org/z/91153r>_):

  .. code:: c++

   #include <fmt/color.h>
  
   int main() {
     std::string out;
     fmt::format_to(std::back_inserter(out),
                    fmt::emphasis::bold | fg(fmt::color::red),
                    "The answer is {}.", 42);
   }
  

  Thanks @Naios (Denis Blank) <https://github.com/Naios>_.

  • Made the '#' specifier emit trailing zeros in addition to the decimal point (#1797 <https://github.com/fmtlib/fmt/issues/1797>). For example (godbolt <https://godbolt.org/z/bhdcW9>_):

  .. code:: c++

   #include <fmt/core.h>
  
   int main() {
     fmt::print("{:#.2g}", 0.5);
   }
  

  prints 0.50.

  • 🔄 Changed the default floating point format to not include .0 for consistency with std::format and std::to_chars (#1893 <https://github.com/fmtlib/fmt/issues/1893>, #1943 <https://github.com/fmtlib/fmt/issues/1943>). It is possible to get the decimal point and trailing zero with the # specifier.

  • 🛠 Fixed an issue with floating-point formatting that could result in addition of a non-significant trailing zero in rare cases e.g. 1.00e-34 instead of 1.0e-34 (#1873 <https://github.com/fmtlib/fmt/issues/1873>, #1917 <https://github.com/fmtlib/fmt/issues/1917>).

  • Made fmt::to_string fallback on ostream insertion operator if the formatter specialization is not provided (#1815 <https://github.com/fmtlib/fmt/issues/1815>, #1829 <https://github.com/fmtlib/fmt/pull/1829>). Thanks @alexezeder (Alexey Ochapov) <https://github.com/alexezeder>_.

  • ➕ Added support for the append mode to the experimental file API and improved fcntl.h detection. (#1847 <https://github.com/fmtlib/fmt/pull/1847>, #1848 <https://github.com/fmtlib/fmt/pull/1848>). Thanks @t-wiser <https://github.com/t-wiser>_.

  • 🛠 Fixed handling of types that have both an implicit conversion operator and an overloaded ostream insertion operator (#1766 <https://github.com/fmtlib/fmt/issues/1766>_).

  • 🛠 Fixed a slicing issue in an internal iterator type (#1822 <https://github.com/fmtlib/fmt/pull/1822>). Thanks @BRevzin (Barry Revzin) <https://github.com/BRevzin>.

  • 🛠 Fixed an issue in locale-specific integer formatting (#1927 <https://github.com/fmtlib/fmt/issues/1927>_).

  • 🛠 Fixed handling of exotic code unit types (#1870 <https://github.com/fmtlib/fmt/issues/1870>, #1932 <https://github.com/fmtlib/fmt/issues/1932>).

  • Improved FMT_ALWAYS_INLINE (#1878 <https://github.com/fmtlib/fmt/pull/1878>). Thanks @jk-jeon (Junekey Jeon) <https://github.com/jk-jeon>.

  • ✂ Removed dependency on windows.h (#1900 <https://github.com/fmtlib/fmt/pull/1900>). Thanks @bernd5 (Bernd Baumanns) <https://github.com/bernd5>.

  • ⚡️ Optimized counting of decimal digits on MSVC (#1890 <https://github.com/fmtlib/fmt/pull/1890>). Thanks @mwinterb <https://github.com/mwinterb>.

  • 👌 Improved documentation (#1772 <https://github.com/fmtlib/fmt/issues/1772>, #1775 <https://github.com/fmtlib/fmt/pull/1775>, #1792 <https://github.com/fmtlib/fmt/pull/1792>, #1838 <https://github.com/fmtlib/fmt/pull/1838>, #1888 <https://github.com/fmtlib/fmt/pull/1888>, #1918 <https://github.com/fmtlib/fmt/pull/1918>, #1939 <https://github.com/fmtlib/fmt/pull/1939>). Thanks @leolchat (Léonard Gérard) <https://github.com/leolchat>, @pepsiman (Malcolm Parsons) <https://github.com/pepsiman>, @Klaim (Joël Lamotte) <https://github.com/Klaim>, @ravijanjam (Ravi J) <https://github.com/ravijanjam>, @francesco-st <https://github.com/francesco-st>, @udnaan (Adnan) <https://github.com/udnaan>_.

  • ⬇️ Added the FMT_REDUCE_INT_INSTANTIATIONS CMake option that reduces the binary code size at the cost of some integer formatting performance. This can be useful for extremely memory-constrained embedded systems (#1778 <https://github.com/fmtlib/fmt/issues/1778>, #1781 <https://github.com/fmtlib/fmt/pull/1781>). Thanks @kammce (Khalil Estell) <https://github.com/kammce>_.

  • 👉 Added the FMT_USE_INLINE_NAMESPACES macro to control usage of inline namespaces (#1945 <https://github.com/fmtlib/fmt/pull/1945>). Thanks @darklukee <https://github.com/darklukee>.

  • 👌 Improved build configuration (#1760 <https://github.com/fmtlib/fmt/pull/1760>, #1770 <https://github.com/fmtlib/fmt/pull/1770>, #1779 <https://github.com/fmtlib/fmt/issues/1779>, #1783 <https://github.com/fmtlib/fmt/pull/1783>, #1823 <https://github.com/fmtlib/fmt/pull/1823>). Thanks @dvetutnev (Dmitriy Vetutnev) <https://github.com/dvetutnev>, @xvitaly (Vitaly Zaitsev) <https://github.com/xvitaly>, @tambry (Raul Tambre) <https://github.com/tambry>, @medithe <https://github.com/medithe>, @martinwuehrer (Martin Wührer) <https://github.com/martinwuehrer>.

  • 🛠 Fixed various warnings and compilation issues (#1790 <https://github.com/fmtlib/fmt/pull/1790>, #1802 <https://github.com/fmtlib/fmt/pull/1802>, #1808 <https://github.com/fmtlib/fmt/pull/1808>, #1810 <https://github.com/fmtlib/fmt/issues/1810>, #1811 <https://github.com/fmtlib/fmt/issues/1811>, #1812 <https://github.com/fmtlib/fmt/pull/1812>, #1814 <https://github.com/fmtlib/fmt/pull/1814>, #1816 <https://github.com/fmtlib/fmt/pull/1816>, #1817 <https://github.com/fmtlib/fmt/pull/1817>, #1818 <https://github.com/fmtlib/fmt/pull/1818>, #1825 <https://github.com/fmtlib/fmt/issues/1825>, #1836 <https://github.com/fmtlib/fmt/pull/1836>, #1855 <https://github.com/fmtlib/fmt/pull/1855>, #1856 <https://github.com/fmtlib/fmt/pull/1856>, #1860 <https://github.com/fmtlib/fmt/pull/1860>, #1877 <https://github.com/fmtlib/fmt/pull/1877>, #1879 <https://github.com/fmtlib/fmt/pull/1879>, #1880 <https://github.com/fmtlib/fmt/pull/1880>, #1896 <https://github.com/fmtlib/fmt/issues/1896>, #1897 <https://github.com/fmtlib/fmt/pull/1897>, #1898 <https://github.com/fmtlib/fmt/pull/1898>, #1904 <https://github.com/fmtlib/fmt/issues/1904>, #1908 <https://github.com/fmtlib/fmt/pull/1908>, #1911 <https://github.com/fmtlib/fmt/issues/1911>, #1912 <https://github.com/fmtlib/fmt/issues/1912>, #1928 <https://github.com/fmtlib/fmt/issues/1928>, #1929 <https://github.com/fmtlib/fmt/pull/1929>, #1935 <https://github.com/fmtlib/fmt/issues/1935>, #1937 <https://github.com/fmtlib/fmt/pull/1937>, #1942 <https://github.com/fmtlib/fmt/pull/1942>, #1949 <https://github.com/fmtlib/fmt/issues/1949>). Thanks @TheQwertiest <https://github.com/TheQwertiest>, @medithe <https://github.com/medithe>, @martinwuehrer (Martin Wührer) <https://github.com/martinwuehrer>, @n16h7hunt3r <https://github.com/n16h7hunt3r>, @Othereum (Seokjin Lee) <https://github.com/Othereum>, @gsjaardema (Greg Sjaardema) <https://github.com/gsjaardema>, @AlexanderLanin (Alexander Lanin) <https://github.com/AlexanderLanin>, @gcerretani (Giovanni Cerretani) <https://github.com/gcerretani>, @chronoxor (Ivan Shynkarenka) <https://github.com/chronoxor>, @noizefloor (Jan Schwers) <https://github.com/noizefloor>, @akohlmey (Axel Kohlmeyer) <https://github.com/akohlmey>, @jk-jeon (Junekey Jeon) <https://github.com/jk-jeon>, @rimathia <https://github.com/rimathia>, @rglarix (Riccardo Ghetta (larix)) <https://github.com/rglarix>, @moiwi <https://github.com/moiwi>, @heckad (Kazantcev Andrey) <https://github.com/heckad>, @MarcDirven <https://github.com/MarcDirven>. @BartSiwek (Bart Siwek) <https://github.com/BartSiwek>, @darklukee <https://github.com/darklukee>.

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