Added the s specifier for std::error_code. It allows formatting an error message as a string. For example:

#include <fmt/std.h>

int main() {
  auto ec = std::make_error_code(std::errc::no_such_file_or_directory);
  fmt::print("{:s}\n", ec);
}

prints

No such file or directory

(The actual message is platform-specific.)

Fixed formatting of std::chrono::local_time and tm (https://github.com/fmtlib/fmt/issues/3815, https://github.com/fmtlib/fmt/issues/4350). For example (godbolt):

#include <fmt/chrono.h>

int main() {
  std::chrono::zoned_time zt(
    std::chrono::current_zone(),
    std::chrono::system_clock::now());
  fmt::print("{}", zt.get_local_time());
}

is now formatted consistenly across platforms.

Added diagnostics for cases when timezone information is not available. For example:

fmt::print("{:Z}", std::chrono::local_seconds());

now gives a compile-time error.

Deprecated fmt::localtime in favor of std::localtime.

Fixed compilation with GCC 15 and C++20 modules enabled (https://github.com/fmtlib/fmt/pull/4347). Thanks @tkhyn.

Fixed handling of named arguments in format specs (https://github.com/fmtlib/fmt/issues/4360, https://github.com/fmtlib/fmt/pull/4361). Thanks @dinomight.

Added error reporting for duplicate named arguments (https://github.com/fmtlib/fmt/pull/4367). Thanks @dinomight.

Fixed formatting of long with FMT_BUILTIN_TYPES=0 (https://github.com/fmtlib/fmt/issues/4375, https://github.com/fmtlib/fmt/issues/4394).

Optimized text_style using bit packing (https://github.com/fmtlib/fmt/pull/4363). Thanks @LocalSpook.

Added support for incomplete types (https://github.com/fmtlib/fmt/issues/3180, https://github.com/fmtlib/fmt/pull/4383). Thanks @LocalSpook.

Fixed a flush issue in fmt::print when using libstdc++ (https://github.com/fmtlib/fmt/issues/4398).

Fixed fmt::println usage with FMT_ENFORCE_COMPILE_STRING and legacy compile-time checks (https://github.com/fmtlib/fmt/pull/4407). Thanks @madmaxoft.

Removed legacy header fmt/core.h from docs (https://github.com/fmtlib/fmt/pull/4421, https://github.com/fmtlib/fmt/pull/4422). Thanks @krzysztofkortas.

Worked around limitations of __builtin_strlen during constant evaluation (https://github.com/fmtlib/fmt/issues/4423, https://github.com/fmtlib/fmt/pull/4429). Thanks @BRevzin.

Worked around a bug in MSVC v141 (https://github.com/fmtlib/fmt/issues/4412, https://github.com/fmtlib/fmt/pull/4413). Thanks @hirohira9119.

Removed the fmt_detail namespace (https://github.com/fmtlib/fmt/issues/4324).

Removed specializations of std::is_floating_point in tests (https://github.com/fmtlib/fmt/issues/4417).

Fixed a CMake error when setting CMAKE_MODULE_PATH in the pedantic mode (https://github.com/fmtlib/fmt/pull/4426). Thanks @rlalik.

Updated the Bazel config (https://github.com/fmtlib/fmt/pull/4400). Thanks @Vertexwahn.