[BUG]: Investigate nvcc 12.9 segfault when building STF header unittests

[alliepiper]

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

CUDA Experimental (cudax)

Describe the bug

Several of the header unittest in CUDASTF are causing nvcc 12.9 to segfault. Eg. https://github.com/NVIDIA/cccl/actions/runs/14798607000/job/41559113597?pr=4624

The offending bit of code can be skipped by applying this patch: f419d85?diff=unified&w=1

How to Reproduce

1. Use CTK 12.9 (devcontainers added in this PR)
2. Ensure that the patch to cudax/include/cuda/experimental/__stf/internal/execution_policy.cuh above isn't applied.
3. ci/build_cudax.sh

Expected behavior

Compilation should succeed.

Reproduction link

No response

Operating System

No response

nvidia-smi output

No response

NVCC version

nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2025 NVIDIA Corporation
Built on Wed_Apr__9_19:24:57_PDT_2025
Cuda compilation tools, release 12.9, V12.9.41
Build cuda_12.9.r12.9/compiler.35813241_0

[miscco]

Did you file a nvbug against the compiler?