Optimized the default floating point formatting (https://github.com/fmtlib/fmt/issues/3675, https://github.com/fmtlib/fmt/issues/4516). In particular, formatting a double with format string compilation into a stack allocated buffer is more than 60% faster in version 12.0 compared to 11.2 according to dtoa-benchmark:

Function  Time (ns)  Speedup
fmt11        34.471    1.00x
fmt12        21.000    1.64x

Added constexpr support to fmt::format. For example:

#include <fmt/compile.h>

using namespace fmt::literals;
std::string s = fmt::format(""_cf, 42);

now works at compile time provided that std::string supports constexpr (https://github.com/fmtlib/fmt/issues/3403, https://github.com/fmtlib/fmt/pull/4456). Thanks @msvetkin.

Added FMT_STATIC_FORMAT that allows formatting into a string of the exact required size at compile time.

For example:

#include <fmt/compile.h>

constexpr auto s = FMT_STATIC_FORMAT("{}", 42);

compiles to just

__ZL1s:
      .asciiz "42"

It can be accessed as a C string with s.c_str() or as a string view with s.str().

Improved C++20 module support (https://github.com/fmtlib/fmt/pull/4451, https://github.com/fmtlib/fmt/pull/4459, https://github.com/fmtlib/fmt/pull/4476, https://github.com/fmtlib/fmt/pull/4488, https://github.com/fmtlib/fmt/issues/4491, https://github.com/fmtlib/fmt/pull/4495). Thanks @arBmind, @tkhyn, @Mishura4, @anonymouspc and @autoantwort.

Switched to using estimated display width in precision. For example:

fmt::print("|{:.4}|\n|1234|\n", "🐱🐱🐱");

prints

because 🐱 has an estimated width of 2 (https://github.com/fmtlib/fmt/issues/4272, https://github.com/fmtlib/fmt/pull/4443, https://github.com/fmtlib/fmt/pull/4475). Thanks @nikhilreddydev and @localspook.

Fix interaction between debug presentation, precision, and width for strings (https://github.com/fmtlib/fmt/pull/4478). Thanks @localspook.

Implemented allocator propagation on basic_memory_buffer move (https://github.com/fmtlib/fmt/issues/4487, https://github.com/fmtlib/fmt/pull/4490). Thanks @toprakmurat.

Fixed an ambiguity between std::reference_wrapper<T> and format_as formatters (https://github.com/fmtlib/fmt/issues/4424, https://github.com/fmtlib/fmt/pull/4434). Thanks @jeremy-rifkin.

Removed the following deprecated APIs:

• has_formatter: use is_formattable instead,
• basic_format_args::parse_context_type, basic_format_args::formatter_type and similar aliases in context types,
• wide stream overload of fmt::printf,
• wide stream overloads of fmt::print that take text styles,
• is_*char traits, - fmt::localtime.

Deprecated wide overloads of fmt::fprintf and fmt::sprintf.

Improved diagnostics for the incorrect usage of fmt::ptr (https://github.com/fmtlib/fmt/pull/4453). Thanks @TobiSchluter.

Made handling of ANSI escape sequences more efficient (https://github.com/fmtlib/fmt/pull/4511, https://github.com/fmtlib/fmt/pull/4528). Thanks @localspook and @Anas-Hamdane.

Fixed a buffer overflow on all emphasis flags set (https://github.com/fmtlib/fmt/pull/4498). Thanks @dominicpoeschko.

Fixed an integer overflow for precision close to the max int value.

Fixed compatibility with WASI (https://github.com/fmtlib/fmt/issues/4496, https://github.com/fmtlib/fmt/pull/4497). Thanks @whitequark.

Fixed back_insert_iterator detection, preventing a fallback on slower path that handles arbitrary iterators (https://github.com/fmtlib/fmt/issues/4454).

Fixed handling of invalid glibc FILE buffers (https://github.com/fmtlib/fmt/issues/4469).

Added wchar_t support to the std::byte formatter (https://github.com/fmtlib/fmt/issues/4479, https://github.com/fmtlib/fmt/pull/4480). Thanks @phprus.

Changed component prefix from fmt- to fmt_ for compatibility with NSIS/CPack on Windows, e.g. fmt-doc changed to fmt_doc (https://github.com/fmtlib/fmt/issues/4441, https://github.com/fmtlib/fmt/pull/4442). Thanks @n-stein.

Added the FMT_CUSTOM_ASSERT_FAIL macro to simplify providing a custom fmt::assert_fail implementation (https://github.com/fmtlib/fmt/pull/4505). Thanks @HazardyKnusperkeks.

Switched to FMT_THROW on reporting format errors so that it can be overriden by users when exceptions are disabled (https://github.com/fmtlib/fmt/pull/4521). Thanks @HazardyKnusperkeks.

Improved master project detection and disabled install targets when using {fmt} as a subproject by default (https://github.com/fmtlib/fmt/pull/4536). Thanks @crueter.

Made various code improvements (https://github.com/fmtlib/fmt/pull/4445, https://github.com/fmtlib/fmt/pull/4448, https://github.com/fmtlib/fmt/pull/4473, https://github.com/fmtlib/fmt/pull/4522). Thanks @localspook, @tchaikov and @way4sahil.

Added Conan instructions to the docs (https://github.com/fmtlib/fmt/pull/4537). Thanks @uilianries.

Removed Bazel files to avoid issues with downstream packaging (https://github.com/fmtlib/fmt/pull/4530). Thanks @mering.

Added more entries for generated files to .gitignore (https://github.com/fmtlib/fmt/pull/4355, https://github.com/fmtlib/fmt/pull/4512). Thanks @dinomight and @localspook.

Fixed various warnings and compilation issues (https://github.com/fmtlib/fmt/pull/4447, https://github.com/fmtlib/fmt/issues/4470, https://github.com/fmtlib/fmt/pull/4474, https://github.com/fmtlib/fmt/pull/4477, https://github.com/fmtlib/fmt/pull/4471, https://github.com/fmtlib/fmt/pull/4483, https://github.com/fmtlib/fmt/pull/4515, https://github.com/fmtlib/fmt/issues/4533, https://github.com/fmtlib/fmt/pull/4534). Thanks @dodomorandi, @localspook, @remyjette, @Tomek-Stolarczyk, @Mishura4, @mattiasljungstrom and @FatihBAKIR.