fmt::formatted_size now works at compile time (#3026). For example (godbolt):

#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).

Fixed handling of invalid UTF-8 (#3038, #3044, #3056). Thanks @phprus (Vladislav Shchapov) and @skeeto (Christopher Wellons).

Improved Unicode support in ostream overloads of print (#2994, #3001, #3025). Thanks @dimztimz (Dimitrij Mijoski).

Fixed handling of the sign specifier in localized formatting on systems with 32-bit wchar_t (#3041).

Added support for wide streams to fmt::streamed (#2994). Thanks @phprus (Vladislav Shchapov).

Added the n specifier that disables the output of delimiters when formatting ranges (#2981, #2983). For example (godbolt):

#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).

Worked around problematic std::string_view constructors introduced in C++23 (#3030, #3050). Thanks @strega-nil-ms (nicole mazzuca).

Improve handling (exclusion) of recursive ranges (#2968, #2974). Thanks @Dani-Hub (Daniel Krügler).

Improved error reporting in format string compilation (#3055).

Improved the implementation of Dragonbox, the algorithm used for the default floating-point formatting (#2984). Thanks @jk-jeon (Junekey Jeon).

Fixed issues with floating-point formatting on exotic platforms.

Improved the implementation of chrono formatting (#3010). Thanks @phprus (Vladislav Shchapov).

Improved documentation (#2966, #3009, #3020, #3037). Thanks @mwinterb, @jcelerier (Jean-Michaël Celerier) and @remiburtin (Rémi Burtin).

Improved build configuration (#2991, #2995, #3004, #3007, #3040). Thanks @dimztimz (Dimitrij Mijoski) and @hwhsu1231 (Haowei Hsu).

Fixed various warnings and compilation issues (#2969, #2971, #2975, #2982, #2985, #2988, #3000, #3006, #3014, #3015, #3021, #3023, #3024, #3029, #3043, #3052, #3053, #3054). Thanks @h-friederich (Hannes Friederich), @dimztimz (Dimitrij Mijoski), @olupton (Olli Lupton), @bernhardmgruber (Bernhard Manfred Gruber), @phprus (Vladislav Shchapov).

Pull Requests

• Add xchar support for fmt::streamed(). by @phprus in https://github.com/fmtlib/fmt/pull/2961
• Fixed typo in changelog example by @mwinterb in https://github.com/fmtlib/fmt/pull/2966
• Exclude recursive ranges from the formatter specialization for ranges by @Dani-Hub in https://github.com/fmtlib/fmt/pull/2974
• Pointless comparison warnings by @federico-busato in https://github.com/fmtlib/fmt/pull/2971
• The n specifier for ranges. by @brevzin in https://github.com/fmtlib/fmt/pull/2981
• Fix for EDG frontend (Intel, NVHPC compilers) by @phprus in https://github.com/fmtlib/fmt/pull/2982
• Yet another simplification of Dragonbox by @jk-jeon in https://github.com/fmtlib/fmt/pull/2984
• Add additional search paths for doxygen on Windows by @hwhsu1231 in https://github.com/fmtlib/fmt/pull/2991
• Fixes IBM XLC behavior with uint128 fallback by @federico-busato in https://github.com/fmtlib/fmt/pull/2985
• Reduce filesize of the tests on MinGW by @dimztimz in https://github.com/fmtlib/fmt/pull/2995
• Improve Unicode handling when writing to an ostream on Windows by @dimztimz in https://github.com/fmtlib/fmt/pull/2994
• Add fmt:: namespace to doc by @jcelerier in https://github.com/fmtlib/fmt/pull/3009
• Range formatter by @brevzin in https://github.com/fmtlib/fmt/pull/2983
• Fix Unicode handling for ostream under Windows with libc++. by @dimztimz in https://github.com/fmtlib/fmt/pull/3001
• Improve CI on Windows, deprecate AppVeyor by @dimztimz in https://github.com/fmtlib/fmt/pull/3007
• Simplify and improve chrono formatting by @phprus in https://github.com/fmtlib/fmt/pull/3010
• Suppress unused typedef warning by @h-friederich in https://github.com/fmtlib/fmt/pull/3021
• Remove -Wl,--as-needed linker option by @phprus in https://github.com/fmtlib/fmt/pull/3024
• Use is_utf8() in print(std::ostream&, ...) by @dimztimz in https://github.com/fmtlib/fmt/pull/3025
• Constexpr formatted_size by @marksantaniello in https://github.com/fmtlib/fmt/pull/3026
• Fix testsuite on MinGW + MSVCRT by @dimztimz in https://github.com/fmtlib/fmt/pull/3029
• Fix docs by @remiburtin in https://github.com/fmtlib/fmt/pull/3037
• Prepare for deprecating FindPythonInterp module. by @hwhsu1231 in https://github.com/fmtlib/fmt/pull/3040
• nvhpc/22.3: workaround for c++17 mode by @olupton in https://github.com/fmtlib/fmt/pull/3043
• Fix decoder on broken utf8 sequences. by @phprus in https://github.com/fmtlib/fmt/pull/3044
• Disable non-type template args for nvhpc by @bernhardmgruber in https://github.com/fmtlib/fmt/pull/3053
• Disable bogus -Wstringop-overflow on GCC 11 by @phprus in https://github.com/fmtlib/fmt/pull/3054
• Fix bugs in utf8 decoder by @phprus in https://github.com/fmtlib/fmt/pull/3056

New Contributors

• @hwhsu1231 made their first contribution in https://github.com/fmtlib/fmt/pull/2991
• @dimztimz made their first contribution in https://github.com/fmtlib/fmt/pull/2995
• @h-friederich made their first contribution in https://github.com/fmtlib/fmt/pull/3021
• @marksantaniello made their first contribution in https://github.com/fmtlib/fmt/pull/3026
• @remiburtin made their first contribution in https://github.com/fmtlib/fmt/pull/3037
• @bernhardmgruber made their first contribution in https://github.com/fmtlib/fmt/pull/3053

Full Changelog: https://github.com/fmtlib/fmt/compare/9.0.0...9.1.0