fmtlib/fmt 10.0.0

on GitHub

• Replaced Grisu with a new floating-point formatting algorithm for given precision (#3262, #2750, #3269, #3276). The new algorithm is based on Dragonbox already used for the shortest representation and gives substantial performance improvement:

  • Red: new algorithm

  • Green: new algorithm with FMT_USE_FULL_CACHE_DRAGONBOX defined to 1

  • Blue: old algorithm

  Thanks @jk-jeon (Junekey Jeon).

• Replaced snprintf-based hex float formatter with an internal implementation (#3179, #3203). This removes the last usage of s(n)printf in {fmt}. Thanks @phprus (Vladislav Shchapov).

• Fixed alignment of floating-point numbers with localization (#3263, #3272). Thanks @ShawnZhong (Shawn Zhong).

• Improved C++20 module support (#3134, #3254, #3386, #3387, #3388, #3392, #3397, #3399, #3400). Thanks @laitingsheng (Tinson Lai), @Orvid (Orvid King), @DanielaE (Daniela Engert). Switched to the modules CMake library which allows building {fmt} as a C++20 module with clang:

  CXX=clang++ cmake -DFMT_MODULE=ON .
  make
  

• Made format_as work with any user-defined type and not just enums. For example (godbolt):

  #include <fmt/format.h>
  
  struct floaty_mc_floatface {
    double value;
  };
  
  auto format_as(floaty_mc_floatface f) { return f.value; }
  
  int main() {
    fmt::print("{:8}\n", floaty_mc_floatface{0.42}); // prints "    0.42"
  }

• Removed deprecated implicit conversions for enums and conversions to primitive types for compatibility with std::format and to prevent potential ODR violations. Use format_as instead.

• Added support for fill, align and width to the time point formatter (#3237, #3260, #3275). For example (godbolt):

  #include <fmt/chrono.h>
  
  int main() {
    // prints "    2023"
    fmt::print("{:>8%Y}\n", std::chrono::system_clock::now());
  }

  Thanks @ShawnZhong (Shawn Zhong).

• Implemented formatting of subseconds (#2207, #3117, #3115, #3143, #3144, #3349). For example (godbolt):

  #include <fmt/chrono.h>
  
  int main() {
    // prints 01.234567
    fmt::print("{:%S}\n", std::chrono::microseconds(1234567));
  }

  Thanks @patrickroocks (Patrick Roocks) @phprus (Vladislav Shchapov), @BRevzin (Barry Revzin).

• Added precision support to %S (#3148). Thanks @SappyJoy (Stepan Ponomaryov)

• Added support for std::utc_time (#3098, #3110). Thanks @patrickroocks (Patrick Roocks).

• Switched formatting of std::chrono::system_clock from local time to UTC for compatibility with the standard (#3199, #3230). Thanks @ned14 (Niall Douglas).

• Added support for %Ez and %Oz to chrono formatters. (#3220, #3222). Thanks @phprus (Vladislav Shchapov).

• Improved validation of format specifiers for std::chrono::duration (#3219, #3232). Thanks @ShawnZhong (Shawn Zhong).

• Fixed formatting of time points before the epoch (#3117, #3261). For example (godbolt):

  #include <fmt/chrono.h>
  
  int main() {
    auto t = std::chrono::system_clock::from_time_t(0) -
             std::chrono::milliseconds(250);
    fmt::print("{:%S}\n", t); // prints 59.750000000
  }

  Thanks @ShawnZhong (Shawn Zhong).

• Experimental: implemented glibc extension for padding seconds, minutes and hours (#2959, #3271). Thanks @ShawnZhong (Shawn Zhong).

• Added a formatter for std::exception (#2977, #3012, #3062, #3076, #3119). For example (godbolt):

  #include <fmt/std.h>
  #include <vector>
  
  int main() {
    try {
      std::vector<bool>().at(0);
    } catch(const std::exception& e) {
      fmt::print("{}", e);
    }
  }

  prints:

  vector<bool>::_M_range_check: __n (which is 0) >= this->size() (which is 0)
  

  on libstdc++. Thanks @zach2good (Zach Toogood) and @phprus (Vladislav Shchapov).

• Moved std::error_code formatter from fmt/os.h to fmt/std.h. (#3125). Thanks @phprus (Vladislav Shchapov).

• Added formatters for standard container adapters: std::priority_queue, std::queue and std::stack (#3215, #3279). For example (godbolt):

  #include <fmt/ranges.h>
  #include <stack>
  #include <vector>
  
  int main() {
    auto s = std::stack<bool, std::vector<bool>>();
    for (auto b: {true, false, true}) s.push(b);
    fmt::print("{}\n", s); // prints [true, false, true]
  }

  Thanks @ShawnZhong (Shawn Zhong).

• Added a formatter for std::optional to fmt/std.h. Thanks @tom-huntington.

• Fixed formatting of valueless by exception variants (#3347). Thanks @TheOmegaCarrot.

• Made fmt::ptr accept unique_ptr with a custom deleter (#3177). Thanks @hmbj (Hans-Martin B. Jensen).

• Fixed formatting of noncopyable ranges and nested ranges of chars (#3158 #3286, #3290). Thanks @BRevzin (Barry Revzin).

• Fixed issues with formatting of paths and ranges of paths (#3319, #3321 #3322). Thanks @phprus (Vladislav Shchapov).

• Improved handling of invalid Unicode in paths.

• Enabled compile-time checks on Apple clang 14 and later (#3331). Thanks @cloyce (Cloyce D. Spradling).

• Improved compile-time checks of named arguments (#3105, #3214). Thanks @rbrich (Radek Brich).

• Fixed formatting when both alignment and 0 are given (#3236, #3248). Thanks @ShawnZhong (Shawn Zhong).

• Improved Unicode support in the experimental file API on Windows (#3234, #3293). Thanks @Fros1er (Froster).

• Unified UTF transcoding (#3416). Thanks @phprus (Vladislav Shchapov).

• Added support for UTF-8 digit separators via an experimental locale facet (#1861). For example (godbolt):

  auto loc = std::locale(
    std::locale(), new fmt::format_facet<std::locale>("’"));
  auto s = fmt::format(loc, "{:L}", 1000);

  where ’ is U+2019 used as a digit separator in the de_CH locale.

• Added an overload of formatted_size that takes a locale (#3084, #3087). Thanks @gerboengels.

• Removed the deprecated FMT_DEPRECATED_OSTREAM.

• Fixed a UB when using a null std::string_view with fmt::to_string or format string compilation (#3241, #3244). Thanks @phprus (Vladislav Shchapov).

• Added starts_with to the fallback string_view implementation (#3080). Thanks @phprus (Vladislav Shchapov).

• Added fmt::basic_format_string::get() for compatibility with basic_format_string (#3111). Thanks @huangqinjin.

• Added println for compatibility with C++23 (#3267). Thanks @ShawnZhong (Shawn Zhong).

• Renamed the FMT_EXPORT macro for shared library usage to FMT_LIB_EXPORT.

• Improved documentation (#3108, #3169, #3243). #3404). Thanks @Cleroth and @Vertexwahn.

• Improved build configuration and tests (#3118, #3120, #3188, #3189, #3198, #3205, #3207, #3210, #3240, #3256, #3264, #3299, #3302, #3312, #3317, #3328, #3333, #3369, #3373, #3395, #3406, #3411). Thanks @dimztimz (Dimitrij Mijoski), @phprus (Vladislav Shchapov), @DavidKorczynski, @ChrisThrasher (Chris Thrasher), @FrancoisCarouge (François Carouge), @kennyweiss (Kenny Weiss), @luzpaz, @codeinred (Alecto Irene Perez), @Mixaill (Mikhail Paulyshka), @joycebrum (Joyce), @kevinhwang (Kevin Hwang), @Vertexwahn.

• Fixed a regression in handling empty format specifiers after a colon ({:}) (#3086). Thanks @oxidase (Michael Krasnyk).

• Worked around a broken implementation of std::is_constant_evaluated in some versions of libstdc++ on clang (#3247, #3281). Thanks @phprus (Vladislav Shchapov).

• Fixed formatting of volatile variables (#3068).

• Fixed various warnings and compilation issues (#3057, #3066, #3072, #3082, #3091, #3092, #3093, #3095, #3096, #3097, #3128, #3129, #3137, #3139, #3140, #3142, #3149, #3150, #3154, #3163, #3178, #3184, #3196, #3204, #3206, #3208, #3213, #3216, #3224, #3226, #3228, #3229, #3259, #3274, #3287, #3288, #3292, #3295, #3296, #3298, #3325, #3326, #3334, #3342, #3343, #3351, #3352, #3362, #3365, #3366, #3374, #3377, #3378, #3381, #3398, #3413, #3415). Thanks @phprus (Vladislav Shchapov), @gsjaardema (Greg Sjaardema), @NewbieOrange, @EngineLessCC (VivyaCC), @asmaloney (Andy Maloney), @HazardyKnusperkeks (Björn Schäpers), @sergiud (Sergiu Deitsch), @Youw (Ihor Dutchak), @thesmurph, @czudziakm (Maksymilian Czudziak), @Roman-Koshelev, @chronoxor (Ivan Shynkarenka), @ShawnZhong (Shawn Zhong), @russelltg (Russell Greene), @glebm (Gleb Mazovetskiy), @tmartin-gh, @Zhaojun-Liu (June Liu), @louiswins (Louis Wilson), @mogemimi.

Pull Requests

• Added workarounds for compilers with EDG frontend (LCC and Nvidia) by @phprus in #3057
• Fix compilation error with gcc-7.2.0 by @gsjaardema in #3066
• Add formatter for std::exception by @zach2good in #3062
• Simplify is_variant_like_ check, fix compile error before GCC 11 by @NewbieOrange in #3072
• Add starts_with to fmt::basic_string_view. by @phprus in #3080
• Fix intellisense on Windows by @EngineLessCC in #3082
• Add locale overload for formatted_size (#3084) by @gerboengels in #3087
• Add class name output to formatter for std::exception by @phprus in #3076
• Fix compilation with FMT_ENFORCE_COMPILE_STRING and FMT_WERROR by @asmaloney in #3091
• Fix build error on GCC-9 by @phprus in #3093
• fix gcc <= 7.1 compile errors by @sergiud in #3097
• Fix warnings by @HazardyKnusperkeks in #3095
• Add basic_format_string::get() by @huangqinjin in #3111
• Update CI to Ubuntu 20.04 and to newer versions of actions by @dimztimz in #3118
• Support formatting of time_point with utc_clock by @patrickroocks in #3110
• Set CMAKE_RUNTIME_OUTPUT_DIRECTORY relative to CMAKE_CURRENT_BINARY_DIR by @phprus in #3120
• Normalization of stdlib inline namespace names by @phprus in #3119
• Move formatterstd::error_code from fmt/os.h to fmt/std.h by @phprus in #3125
• Fix broken condition by @phprus in #3129
• Fix options for C++20 experimental module in CMake by @laitingsheng in #3134
• Avoid using uint as a type name by @Youw in #3137
• Support formatting of subseconds by @patrickroocks in #3115
• Remove duplicate template parameter. by @phprus in #3142
• Fix overflow error by @phprus in #3143
• Remove duplicate implementation by @phprus in #3144
• Mention MariaDB amongst the projects that use fmt by @federico-razzoli in #3145
• Fix warning: conditional expression is constant. by @phprus in #3150
• Add locale getter in tm_writer by @SappyJoy in #3147
• fmt::ostream - aggregate buffer instead of inheriting it by @Youw in #3139
• Fixing formatting of range of range of char. by @brevzin in #3158
• Add precision modifier for seconds in chrono format by @SappyJoy in #3148
• Replace format with FMT_STRING. by @phprus in #3162
• Format unique_ptr with custom deleter by @hmbj in #3177
• This skips the scan-test if strptime isn't defined. by @thesmurph in #3184
• Improve CI by @phprus in #3188
• Fix warnings for compilers with EDG frontend by @phprus in #3196
• Replacing snprintf-based hex float formatter with internal implementation by @phprus in #3179
• CI linux: add CIFuzz Github action by @DavidKorczynski in #3198
• Rename leading_v -> leading_xdigit by @phprus in #3203
• Use target_compile_features to specify C++ standard requirement by @ChrisThrasher in #3205
• Skip only strptime dependent test in scan-test by @phprus in #3206
• Remove workaround for GTest bug by @phprus in #3207
• Bump tested CMake version to 3.25 by @phprus in #3210
• Add countl_zero function by @phprus in #3216
• fix #3105 - Compile-time error when mixing named argument with automatic indexing by @rbrich in #3214
• Implement %Ez, %Oz for chrono formatter by @phprus in #3222
• Fix for issue #3228 by @phprus in #3229
• Check chrono spec starts with % by @ShawnZhong in #3232
• small typo in syntax.rst by @Cleroth in #3243
• Fix for issue #3241 by @phprus in #3244
• Ignore 0 character when align is present by @ShawnZhong in #3248
• Remove empty semicolon by @ShawnZhong in #3249
• Improve timezone tests by @phprus in #3240
• Fix build with MSVC C++20 modules by @Orvid in #3254
• Support fill, align & width for time point by @ShawnZhong in #3260
• Fix standard default installation target presence by @FrancoisCarouge in #3264
• Fix negative subsec for time_point by @ShawnZhong in #3261
• Bugfix for fmt::printf on Power9 architecture with the XL compiler by @kennyweiss in #3256
• Implement a new formatting algorithm for small given precision by @jk-jeon in #3269
• Fix localized format for float-point numbers by @ShawnZhong in #3272
• Fix spec "{:}" for time point by @ShawnZhong in #3275
• Refactor countl_zero fallback by @jk-jeon in #3276
• Workaround for incompatibility between libstdc++ consteval-based std::is_constant_evaluated() implementation and clang-14 by @phprus in #3281
• Implement println by @ShawnZhong in #3267
• Visual Studio 2022: fmt/format-inl.h(1145,60): warning C4310: cast truncates constant value #3287 by @chronoxor in #3288
• Allowing formatting non-copyable ranges. by @brevzin in #3290
• Fix errors setting of FMT_USE_FLOAT128 by @Roman-Koshelev in #3259
• Implement glibc ext for sec, min, and hour by @ShawnZhong in #3271
• Add formatters for container adapters by @ShawnZhong in #3279
• Fix OpenBSD build error by @ShawnZhong in #3295
• Add ubuntu mirrors by @phprus in #3302
• change sopen_s to wsopen_s (#3234) by @Fros1er in #3293
• Fix various typos by @luzpaz in #3312
• Add Optional Support by @tom-huntington in #3303
• Fix for issue #3325 by @phprus in #3326
• chore: set permission to cifuzz.yml by @joycebrum in #3328
• Enable consteval for Xcode 14 and later by @cloyce in #3331
• Fix for issue #3319. by @phprus in #3321
• Cleanup dead variable by @ShawnZhong in #3338
• write_floating_seconds: Fall back to ::round by @glebm in #3343
• Fix CUDA nvcc warning by @tmartin-gh in #3352
• fix case of variant which is valueless by exception by @TheOmegaCarrot in #3347
• %T is %H:%M:%S by @brevzin in #3349
• Force use a signed char (On ARM char is unsigned by default) by @phprus in #3362
• Workaround a double-double hexfloat format by @phprus in #3366
• fix compilation for MS-DOS by @Mixaill in #3369
• ranges: Fix extra semi by @HazardyKnusperkeks in #3374
• Fix error C2668 on msvc by @Zhaojun-Liu in #3378
• fix and improve module by @DanielaE in #3386
• Feature/remove obsolete workarounds by @DanielaE in #3388
• Update tests to use recommended MOCK_METHOD by @kevinhwang in #3395
• Fix MSVC C4365 warning (signed/unsigned mismatch) on 32-bit Windows by @louiswins in #3398
• names declared to be exported at the point of introduction into a nam… by @DanielaE in #3392
• Feature/attach to gmf by @DanielaE in #3387
• Name vfprintf clashes with the identically named declaration in 'st… by @DanielaE in #3400
• Remove myself from maintainer list by @foonathan in #3402
• Fix spelling by @Vertexwahn in #3404
• Bazel support by @Vertexwahn in #3406
• Remove .bazelrc mention from Bazel related readme by @Vertexwahn in #3411
• towards better module testing by @DanielaE in #3397
• Add FMT_STRING for format_to() call with clang-cl by @mogemimi in #3413
• modules missing pieces by @DanielaE in #3399
• Unification utf16/utf32 to utf8 conversion by @phprus in #3416

New Contributors

• @zach2good made their first contribution in #3062
• @NewbieOrange made their first contribution in #3072
• @EngineLessCC made their first contribution in #3082
• @gerboengels made their first contribution in #3087
• @asmaloney made their first contribution in #3091
• @huangqinjin made their first contribution in #3111
• @patrickroocks made their first contribution in #3110
• @laitingsheng made their first contribution in #3134
• @Youw made their first contribution in #3137
• @federico-razzoli made their first contribution in #3145
• @SappyJoy made their first contribution in #3147
• @hmbj made their first contribution in #3177
• @thesmurph made their first contribution in #3184
• @DavidKorczynski made their first contribution in #3198
• @ChrisThrasher made their first contribution in #3205
• @rbrich made their first contribution in #3214
• @ShawnZhong made their first contribution in #3232
• @Cleroth made their first contribution in #3243
• @Orvid made their first contribution in #3254
• @FrancoisCarouge made their first contribution in #3264
• @kennyweiss made their first contribution in #3256
• @Fros1er made their first contribution in #3293
• @luzpaz made their first contribution in #3312
• @tom-huntington made their first contribution in #3303
• @joycebrum made their first contribution in #3328
• @cloyce made their first contribution in #3331
• @glebm made their first contribution in #3343
• @tmartin-gh made their first contribution in #3352
• @TheOmegaCarrot made their first contribution in #3347
• @Mixaill made their first contribution in #3369
• @Zhaojun-Liu made their first contribution in #3378
• @kevinhwang made their first contribution in #3395
• @louiswins made their first contribution in #3398
• @mogemimi made their first contribution in #3413

Full Changelog: 9.1.0...10.0.0