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base.h: _BitInt is not available when Clang is used as a host compiler for NVCC#4564

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vitaut merged 2 commits into
fmtlib:masterfrom
valgur:patch-1
Oct 6, 2025
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base.h: _BitInt is not available when Clang is used as a host compiler for NVCC#4564
vitaut merged 2 commits into
fmtlib:masterfrom
valgur:patch-1

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@valgur valgur commented Oct 4, 2025

When using NVCC with Clang as the host compiler (nvcc -ccbin=clang-17), including fmt currently fails (at least on Linux) with

include/fmt/base.h(423): error: identifier "_BitInt" is undefined
  template <int N> using bitint = _BitInt(N);

This PR disables the use of _BitInt in that case.

I was thinking it might be related to NVCC requiring the use of libstdc++ and prohibiting libc++ in most cases, but forcing libc++ with -Xcompiler=-stdlib=libc++ -D_ALLOW_UNSUPPORTED_LIBCPP did not get rid of the error.

I'm guessing it has not cropped up earlier due the use of fmt with CUDA code probably not being too common and Nvidia generally recommending GCC over Clang as the host compiler.

@vitaut vitaut merged commit b580360 into fmtlib:master Oct 6, 2025
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vitaut commented Oct 6, 2025

Merged, thanks!

netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Nov 2, 2025
# 12.1.0 - 2025-10-29

- 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.
msk pushed a commit to msk/pkgsrc that referenced this pull request May 11, 2026
# 12.1.0 - 2025-10-29

- 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.
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2 participants