Build failure in cublaslt_gemm.cu: "cuda" is ambiguous

[XueSongTap]

Describe the bug

Building Transformer Engine from source fails during CUDA compilation with:

transformer_engine/common/gemm/cublaslt_gemm.cu(936): error: "cuda" is ambiguous

  /mnt/cfs/dev/TransformerEngine/transformer_engine/common/gemm/cublaslt_gemm.cu(936): error: "cuda" is ambiguous
      do { if (!(cuda::cublas_version() >= 120205 && cuda::cublas_version() < 130000)) { do { throw ::std::runtime_error(::transformer_engine::concat_strings( "/mnt/cfs/dev/TransformerEngine/transformer_engine/common/gemm/cublaslt_gemm.cu" ":", 936, " in function ", __func__, ": ", ::transformer_engine::concat_strings("Assertion failed: " "cuda::cublas_version() >= 120205 && cuda::cublas_version() < 130000" ". ", ::transformer_engine::concat_strings("Atomic GEMM requires cuBLAS version >=12.2.5 and <13.0.0, but run-time cuBLAS version is ", cuda::cublas_version())))); } while (false); } } while (false)

The failure happens in nvte_cublas_atomic_gemm when compiling the runtime version check that calls cuda::cublas_version().

Steps/Code to reproduce bug

1. Clone Transformer Engine.

2. Build/install from source in editable mode:

export NVTE_FRAMEWORK=pytorch
pip install --no-build-isolation -v -e .

3. Build fails with:

.../transformer_engine/common/gemm/cublaslt_gemm.cu(936): error: "cuda" is ambiguous
do { if (!(cuda::cublas_version() >= 120205 && cuda::cublas_version() < 130000)) { ...

Expected behavior

building success

Environment overview (please complete the following information)

Environment details

• PyTorch version: 2.7.1
• Python version: 3.12
• Transformer Engine version: b9f4013
• CUDA version: cuda_12.9.r12.9
• CUDNN version: 9.16.0

Device details

• GPU model: A800

Additional context

This appears to be a namespace collision in this translation unit: both transformer_engine::cuda and global ::cuda can be visible, so unqualified cuda::cublas_version() becomes ambiguous in some toolchains/environments.

works fine with v2.11

maybe related ：#2631

[pggPL]

Hi, we fixed this error in c3769cb .