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This fixes some implicit conversions that can cause noise when compiling other projects if conversions warnings (-Wconversion -Wsign-conversion in GCC) are enabled.

The "1" used for the bitshift is treated as int, and this causes an
implicit conversion to `UInt` when performing the logical and.
Explicitly casting the number to `UInt` avoids the warning.
Some indices in `include/fmt/base.h` are expressed as `int` types, which
causes an implicit conversion to a `size_t` when they are actually used
as index. Explicitly casting the value avoids the warning.
The number of bits is used to express the size of a buffer. Using an
`int` causes an implicit conversion warning, let's use a `size_t` which
is the right type for the job.
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Please provide a godbolt repro demonstrating the warnings.

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Please provide a godbolt repro demonstrating the warnings.

The warnings appear when fmt is included in a project with the FetchContent, which obviously needs the compilation of fmt. If the project enables the conversion warnings, they just came out.

The best way to reproduce the warnings is just enable the warnings during the compilation of fmt:

cmake -B build -DCMAKE_CXX_FLAGS="-Wconversion -Wsign-conversion"
cmake --build build -j $(nproc)

@vitaut vitaut merged commit ea985e8 into fmtlib:master May 24, 2025
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vitaut commented May 24, 2025

We mostly care about -Wall -Wextra -pedantic but these changes are simple enough (and can be further simplified) so I merged them in, thanks.

@dodomorandi dodomorandi deleted the avoid-implicit-conversion branch May 24, 2025 16:28
mtremer pushed a commit to ipfire/ipfire-2.x that referenced this pull request Nov 6, 2025
- Update from version 11.2.0 to 12.1.0
- Update of rootfile
- so-bump so mpd requires shipping
- Changelog
    12.1.0
	- Optimized `buffer::append`, resulting in up to ~16% improvement on spdlog
	  benchmarks (fmtlib/fmt#4541). Thanks @fyrsta7.
	- Worked around an ABI incompatibility in `std::locale_ref` between clang and
	  gcc (fmtlib/fmt#4573).
	- Made `std::variant` and `std::expected` formatters work with `format_as`
	  (fmtlib/fmt#4574,
	  fmtlib/fmt#4575). Thanks @phprus.
	- Made `fmt::join<string_view>` work with C++ modules
	  (fmtlib/fmt#4379,
	  fmtlib/fmt#4577). Thanks @Arghnews.
	- Exported `fmt::is_compiled_string` and `operator""_cf` from the module
	  (fmtlib/fmt#4544). Thanks @CrackedMatter.
	- Fixed a compatibility issue with C++ modules in clang
	  (fmtlib/fmt#4548). Thanks @tsarn.
	- Added support for cv-qualified types to the `std::optional` formatter
	  (fmtlib/fmt#4561,
	  fmtlib/fmt#4562). Thanks @OleksandrKvl.
	- Added demangling support (used in exception and `std::type_info` formatters)
	  for libc++ and clang-cl
	  (fmtlib/fmt#4542,
	  fmtlib/fmt#4560,
	  fmtlib/fmt#4568,
	  fmtlib/fmt#4571).
	  Thanks @FatihBAKIR and @rohitsutreja.
	- Switched to global `malloc`/`free` to enable allocator customization
	  (fmtlib/fmt#4569,
	  fmtlib/fmt#4570). Thanks @rohitsutreja.
	- Made the `FMT_USE_CONSTEVAL` macro configurable by users
	  (fmtlib/fmt#4546). Thanks @SnapperTT.
	- Fixed compilation with locales disabled in the header-only mode
	  (fmtlib/fmt#4550).
	- Fixed compilation with clang 21 and `-std=c++20`
	  (fmtlib/fmt#4552).
	- Fixed a dynamic linking issue with clang-cl
	  (fmtlib/fmt#4576,
	  fmtlib/fmt#4584). Thanks @FatihBAKIR.
	- Fixed a warning suppression leakage on gcc
	  (fmtlib/fmt#4588). Thanks @ZedThree.
	- Made more internal color APIs `constexpr`
	  (fmtlib/fmt#4581). Thanks @ishani.
	- Fixed compatibility with clang as a host compiler for NVCC
	  (fmtlib/fmt#4564). Thanks @valgur.
	- Fixed various warnings and lint issues
	  (fmtlib/fmt#4565,
	  fmtlib/fmt#4572,
	  fmtlib/fmt#4557).
	  Thanks @LiangHuDream and @teruyamato0731.
	- Improved documentation
	  (fmtlib/fmt#4549,
	  fmtlib/fmt#4551,
	  fmtlib/fmt#4566,
	  fmtlib/fmt#4567,
	  fmtlib/fmt#4578,).
	  Thanks @teruyamato0731, @petersteneteg and @zimmerman-dev.
    12.0.0
	- Optimized the default floating point formatting
	  (fmtlib/fmt#3675,
	  fmtlib/fmt#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](https://github.com/fmtlib/dtoa-benchmark):
	  ```
	  Function  Time (ns)  Speedup
	  fmt11        34.471    1.00x
	  fmt12        21.000    1.64x
	  ```
	  <img width="766" height="609" src="https://github.com/user-attachments/assets/d7d768ad-7543-468c-b0bb-449abf73b31b" />
	- Added `constexpr` support to `fmt::format`. For example:
	  ```c++
	  #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`
	  (fmtlib/fmt#3403,
	  fmtlib/fmt#4456). Thanks @msvetkin.
	- Added `FMT_STATIC_FORMAT` that allows formatting into a string of the exact
	  required size at compile time.
	  For example:
	  ```c++
	  #include <fmt/compile.h>
	  constexpr auto s = FMT_STATIC_FORMAT("{}", 42);
	  ```
	  compiles to just
	  ```s
	  __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
	  (fmtlib/fmt#4451,
	  fmtlib/fmt#4459,
	  fmtlib/fmt#4476,
	  fmtlib/fmt#4488,
	  fmtlib/fmt#4491,
	  fmtlib/fmt#4495).
	  Thanks @arBmind, @tkhyn, @Mishura4, @anonymouspc and @autoantwort.
	- Switched to using estimated display width in precision. For example:
	  ```c++
	  fmt::print("|{:.4}|\n|1234|\n", "🐱🐱🐱");
	  ```
	  prints
	  ![](https://github.com/user-attachments/assets/6c4446b3-13eb-43b9-b74a-b4543540ad6a)
	  because `🐱` has an estimated width of 2
	  (fmtlib/fmt#4272,
	  fmtlib/fmt#4443,
	  fmtlib/fmt#4475).
	  Thanks @nikhilreddydev and @localspook.
	- Fix interaction between debug presentation, precision, and width for strings
	  (fmtlib/fmt#4478). Thanks @localspook.
	- Implemented allocator propagation on `basic_memory_buffer` move
	  (fmtlib/fmt#4487,
	  fmtlib/fmt#4490). Thanks @toprakmurat.
	- Fixed an ambiguity between `std::reference_wrapper<T>` and `format_as`
	  formatters (fmtlib/fmt#4424,
	  fmtlib/fmt#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`
	  (fmtlib/fmt#4453). Thanks @TobiSchluter.
	- Made handling of ANSI escape sequences more efficient
	  (fmtlib/fmt#4511,
	  fmtlib/fmt#4528).
	  Thanks @localspook and @Anas-Hamdane.
	- Fixed a buffer overflow on all emphasis flags set
	  (fmtlib/fmt#4498). Thanks @dominicpoeschko.
	- Fixed an integer overflow for precision close to the max `int` value.
	- Fixed compatibility with WASI (fmtlib/fmt#4496,
	  fmtlib/fmt#4497). Thanks @whitequark.
	- Fixed `back_insert_iterator` detection, preventing a fallback on slower path
	  that handles arbitrary iterators (fmtlib/fmt#4454).
	- Fixed handling of invalid glibc `FILE` buffers
	  (fmtlib/fmt#4469).
	- Added `wchar_t` support to the `std::byte` formatter
	  (fmtlib/fmt#4479,
	  fmtlib/fmt#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`
	  (fmtlib/fmt#4441,
	  fmtlib/fmt#4442). Thanks @n-stein.
	- Added the `FMT_CUSTOM_ASSERT_FAIL` macro to simplify providing a custom
	  `fmt::assert_fail` implementation (fmtlib/fmt#4505).
	  Thanks @HazardyKnusperkeks.
	- Switched to `FMT_THROW` on reporting format errors so that it can be
	  overriden by users when exceptions are disabled
	  (fmtlib/fmt#4521). Thanks @HazardyKnusperkeks.
	- Improved master project detection and disabled install targets when using
	  {fmt} as a subproject by default (fmtlib/fmt#4536).
	  Thanks @crueter.
	- Made various code improvements
	  (fmtlib/fmt#4445,
	  fmtlib/fmt#4448,
	  fmtlib/fmt#4473,
	  fmtlib/fmt#4522).
	  Thanks @localspook, @tchaikov and @way4sahil.
	- Added Conan instructions to the docs
	  (fmtlib/fmt#4537). Thanks @uilianries.
	- Removed Bazel files to avoid issues with downstream packaging
	  (fmtlib/fmt#4530). Thanks @mering.
	- Added more entries for generated files to `.gitignore`
	  (fmtlib/fmt#4355,
	  fmtlib/fmt#4512).
	  Thanks @dinomight and @localspook.
	- Fixed various warnings and compilation issues
	  (fmtlib/fmt#4447,
	  fmtlib/fmt#4470,
	  fmtlib/fmt#4474,
	  fmtlib/fmt#4477,
	  fmtlib/fmt#4471,
	  fmtlib/fmt#4483,
	  fmtlib/fmt#4515,
	  fmtlib/fmt#4533,
	  fmtlib/fmt#4534).
	  Thanks @dodomorandi, @localspook, @remyjette, @Tomek-Stolarczyk, @Mishura4,
	  @mattiasljungstrom and @FatihBAKIR.

Signed-off-by: Adolf Belka <[email protected]>
Signed-off-by: Michael Tremer <[email protected]>
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2 participants