compiler-errorscudanvcccompiler-bug

Why is NVCC more strict with constexpr than non-constexpr host functions?

Consider the following code:

constexpr __host__   void foo() {  }

__global__ void baz()
{
    if constexpr(1==2) { foo(); }
}

this fails to compile with CUDA 11.3.1's NVCC. However, if I remove the constexpr from foo() - it does compile.

How come? Is this a bug?

Solution

  • This was an NVCC bug, as of CUDA 11.3.1, filed as:

    https://developer.nvidia.com/nvidia_bug/3328502

    (it's difficult to access their bug tracking system, try going through https://developer.nvidia.com first to login, then look at your bugs, then replace the bug number.)

    It was fixed at some point before CUDA 12.0.