[BUG]: thrust/execution_policy.h is not safe to include when compiling with a host compiler

[vyasr]

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

Thrust

Describe the bug

This issue is an extension of #3483. If, given the same example from that issue, the CUDA runtime headers are available, then compilation proceeds further but fails with this traceback

-- Build files have been written to: /home/vyasr/local/cccl/examples/basic/build
[ 50%] Building CXX object CMakeFiles/example_project.dir/example.cpp.o
In file included from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/cub/../../../cub/cub/detail/launcher/cuda_runtime.cuh:15,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/cub/../../../cub/cub/util_device.cuh:728,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/cuda/detail/util.h:41,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/cuda/detail/malloc_and_free.h:36,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/detail/adl/malloc_and_free.h:50,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/detail/generic/memory.inl:32,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/detail/generic/memory.h:70,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/detail/reference.h:38,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/memory.h:35,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/detail/allocator/temporary_allocator.h:31,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/detail/temporary_array.h:46,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/cuda/detail/internal/copy_cross_system.h:47,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/cuda/detail/copy.h:79,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/detail/adl/copy.h:50,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/detail/copy.inl:29,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/detail/copy.h:72,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/detail/sequential/merge.inl:28,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/detail/sequential/merge.h:81,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/cpp/detail/merge.h:30,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/cpp/execution_policy.h:59,
                 from /home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/execution_policy.h:40,
                 from /home/vyasr/local/cccl/examples/basic/example.cpp:1:
/home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/cuda/detail/core/triple_chevron_launch.h: In member function ‘cudaError_t thr
ust::THRUST_300000_SM___CUDA_ARCH_LIST___NS::cuda_cub::launcher::triple_chevron::doit_host(K, const Args& ...) const’:
/home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/cuda/detail/core/triple_chevron_launch.h:112:10: error: expected primary-expr
ession before ‘<’ token
  112 |       k<<<grid, block, shared_mem, stream>>>(args...);
      |          ^
/home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/cuda/detail/core/triple_chevron_launch.h:112:44: error: expected primary-expr
ession before ‘>’ token
  112 |       k<<<grid, block, shared_mem, stream>>>(args...);
      |                                            ^
/home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/cuda/detail/core/triple_chevron_launch.h:112:50: error: expected ‘)’ before ‘
...’ token
  112 |       k<<<grid, block, shared_mem, stream>>>(args...);
      |                                                  ^~~
/home/vyasr/local/cccl/examples/basic/build/_deps/cccl-src/lib/cmake/thrust/../../../thrust/thrust/system/cuda/detail/core/triple_chevron_launch.h:112:45: note: to match this ‘(’
  112 |       k<<<grid, block, shared_mem, stream>>>(args...);
      |                                             ^
gmake[2]: *** [CMakeFiles/example_project.dir/build.make:76: CMakeFiles/example_project.dir/example.cpp.o] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:179: CMakeFiles/example_project.dir/all] Error 2

How to Reproduce

Using this CMake (the same as #3483 except that now we use FindCUDAToolkit and link to cudart)

cmake_minimum_required(VERSION 3.26.1 FATAL_ERROR)
project(ExecutionPolicyError CXX)
file(DOWNLOAD
        https://github.com/cpm-cmake/CPM.cmake/releases/download/v0.40.2/CPM.cmake
    ${CMAKE_CURRENT_BINARY_DIR}/CPM.cmake LOG download_log)
include(${CMAKE_CURRENT_BINARY_DIR}/CPM.cmake)
CPMAddPackage(
    NAME CCCL
    GITHUB_REPOSITORY nvidia/cccl
    GIT_TAG main
)
find_package(CUDAToolkit REQUIRED)
add_executable(example_project example.cpp)
target_link_libraries(example_project PRIVATE CCCL::CCCL CUDA::cudart)

and this C++ file (same as #3483)

#include <thrust/execution_policy.h>

we observe the above compilation error.

Expected behavior

I expect this to compile successfully.

Reproduction link

No response

Operating System

Ubuntu 24.04

nvidia-smi output

N/A (not compiling for the GPU)

NVCC version

N/A (not compiling with nvcc)

[vyasr]

#3378 by @caugonnet is a potential fix for this issue.