llvm-project

e719e93d - [CUDA][HIP] Fix CTAD for host/device constructors (#168711)

[CUDA][HIP] Fix CTAD for host/device constructors (#168711) Clang currently does not allow using CTAD in CUDA/HIP device functions since deduction guides are treated as host-only. This patch fixes that by treating deduction guides as host+device. The rationale is that deduction guides do not actually generate code in IR, and there is an existing check for device/host correctness for constructors. The patch also suppresses duplicate implicit deduction guides from host/device constructors with identical signatures and constraints to prevent ambiguity. For CUDA/HIP, deduction guides are now always implicitly enabled for both host and device, which matches nvcc's effective behavior. Unlike nvcc, which silently ignores explicit CUDA/HIP target attributes on deduction guides, Clang diagnoses such attributes as errors to keep the syntax clean and avoid confusion. This ensures CTAD works correctly in CUDA/HIP for constructors with different target attributes and provides clearer diagnostics when users attempt to annotate deduction guides with CUDA/HIP target attributes. Example: ``` #include <tuple> __host__ __device__ void func() { std::tuple<int, int> t = std::tuple(1, 1); } ``` This compiles with nvcc but fails with clang for CUDA/HIP without this fix. Reference: https://godbolt.org/z/WhT1GrhWE Fixes: https://github.com/ROCm/ROCm/issues/5646 Fixes: https://github.com/llvm/llvm-project/issues/146646