[BUG]: Assertion compilation fail on Visual Studio clang

[asmelko]

Is this a duplicate?

• I confirmed there appear to be no duplicate issues for this bug and that I agree to the Code of Conduct

Type of Bug

Compile-time Error

Component

General CCCL

Describe the bug

Attempting to compile a simple CCCL file in debug mode with Visual Studio Clang fails with undeclared identifier '__assert_fail'.

In file included from test/main.cpp:1:
In file included from C:/Users/asmelko/Desktop/PhysiCore/build/llvm-debug/vcpkg_installed/x64-windows/include/cccl\cuda/std/span:54:
In file included from C:/Users/asmelko/Desktop/PhysiCore/build/llvm-debug/vcpkg_installed/x64-windows/include/cccl\cuda/std/array:42:
C:/Users/asmelko/Desktop/PhysiCore/build/llvm-debug/vcpkg_installed/x64-windows/include/cccl\cuda/std/__utility/unreachable.h:29:3: error: use of undeclared identifier '__assert_fail'
   29 |   _CCCL_ASSERT(false, "unreachable");
      |   ^
C:/Users/asmelko/Desktop/PhysiCore/build/llvm-debug/vcpkg_installed/x64-windows/include/cccl\cuda/std/__cccl/assert.h:147:45: note: expanded from macro '_CCCL_ASSERT'
  147 | #  define _CCCL_ASSERT(expression, message) _CCCL_ASSERT_HOST(expression, message)
      |                                             ^
C:/Users/asmelko/Desktop/PhysiCore/build/llvm-debug/vcpkg_installed/x64-windows/include/cccl\cuda/std/__cccl/assert.h:115:50: note: expanded from macro '_CCCL_ASSERT_HOST'
  115 | #  define _CCCL_ASSERT_HOST(expression, message) _CCCL_ASSERT_IMPL_HOST(expression, message)
      |                                                  ^
C:/Users/asmelko/Desktop/PhysiCore/build/llvm-debug/vcpkg_installed/x64-windows/include/cccl\cuda/std/__cccl/assert.h:86:18: note: expanded from macro '_CCCL_ASSERT_IMPL_HOST'
   86 |     ? (void) 0 : __assert_fail(message, __FILE__, __LINE__, __func__)
      |                  ^

How to Reproduce

1. Create a file main.cpp with the following contents:

#include <cuda/std/span>
int main() { return 0; }

2. Compile debug with Visual Studio clang:

clang -I<cccl include dir> -std=c++20 -DCCCL_ENABLE_ASSERTIONS -DTBB_USE_DEBUG main.cpp

Expected behavior

The aforementioned file should compile.

Reproduction link

No response

Operating System

Windows 11

nvidia-smi output

No response

NVCC version

clang --version
clang version 19.1.1
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\Llvm\x64\bin

Also, running on Visual Studio Community Edition 2022, 17.14.22

[github-actions]

Hi @asmelko!

Thanks for submitting this issue - the CCCL team has been notified and we'll get back to you as soon as we can!
In the mean time, feel free to add any relevant information to this issue.

[asmelko]

I am not sure whether I can rely on cccl supporting Visual Studio clang. But it seems to be working fine in the release mode, when assertions are not present.

[miscco]

clang is not officially supported on MSVC

That said we are always open to improvements such as the PR