Fix clang / nvcc CI build

CMakeLists.txt

@@ -19,6 +19,23 @@ else()
   set(THRUST_TOPLEVEL_PROJECT OFF)
 endif()
 
+## thrust_fix_clang_nvcc_build_for 
+#
+# Modifies the given target to include a fix for the clang host compiler case.
+# The fix consists of force-including a header into each compilation unit.
+#
+function(thrust_fix_clang_nvcc_build_for target)
+  if (UNIX)
+    # Path to the header containing the fix for clang + nvcc < 11.6. For more info,
+    # check the content of this header.
+    set(clang_fix_header_path "${CMAKE_CURRENT_FUNCTION_LIST_DIR}/testing/fix_clang_nvcc_11.5.h")
+
+    # Only affects host compiler
+    target_compile_options(${target} PRIVATE 
+        $<$<COMPILE_LANGUAGE:CUDA>:-include"${clang_fix_header_path}">)
+  endif()
+endfunction()
+
 # This must be done before any languages are enabled:
 if (THRUST_TOPLEVEL_PROJECT)
   include(cmake/ThrustCompilerHacks.cmake)

cmake/ThrustHeaderTesting.cmake

@@ -133,6 +133,8 @@ foreach(thrust_target IN LISTS THRUST_TARGETS)
     )
   endif()
 
+  thrust_fix_clang_nvcc_build_for(${headertest_target})
+
   add_dependencies(thrust.all.headers ${headertest_target})
   add_dependencies(${config_prefix}.all ${headertest_target})
 endforeach()

examples/CMakeLists.txt

@@ -95,6 +95,7 @@ function(thrust_add_example target_name_var example_name example_src thrust_targ
   target_link_libraries(${example_target} ${thrust_target})
   target_include_directories(${example_target} PRIVATE "${Thrust_SOURCE_DIR}/examples")
   thrust_clone_target_properties(${example_target} ${thrust_target})
+  thrust_fix_clang_nvcc_build_for(${example_target})
 
   # Add to the active configuration's meta target
   add_dependencies(${config_meta_target} ${example_target})

internal/benchmark/CMakeLists.txt

@@ -23,6 +23,7 @@ foreach(thrust_target IN LISTS THRUST_TARGETS)
   target_link_libraries(${bench_target} PRIVATE ${thrust_target})
   target_include_directories(${bench_target} PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}")
   thrust_clone_target_properties(${bench_target} ${thrust_target})
+  thrust_fix_clang_nvcc_build_for(${bench_target})
 
   add_dependencies(thrust.all.bench ${bench_target})
   add_dependencies(${config_prefix}.all ${bench_target})

testing/CMakeLists.txt

@@ -87,6 +87,8 @@ function(thrust_add_test target_name_var test_name test_src thrust_target)
     target_compile_definitions(${test_target} PRIVATE THRUST_TEST_DEVICE_SIDE)
   endif()
 
+  thrust_fix_clang_nvcc_build_for(${test_target})
+
   # Add to the active configuration's meta target
   add_dependencies(${config_meta_target} ${test_target})
 

testing/cuda/copy_if.cu

@@ -3,7 +3,6 @@
 #include <thrust/sequence.h>
 #include <thrust/execution_policy.h>
 
-
 template<typename T>
 struct is_even
 {

testing/cuda/stream_per_thread.cmake

@@ -4,6 +4,8 @@ set_target_properties(${test_target} PROPERTIES
     $<$<AND:$<COMPILE_LANGUAGE:CUDA>,$<CUDA_COMPILER_ID:NVIDIA>>:--default-stream=per-thread>
 )
 
+thrust_fix_clang_nvcc_build_for(${test_target})
+
 # NVC++ does not have an equivalent option, and will always
 # use the global stream by default.
 if (CMAKE_CUDA_COMPILER_ID STREQUAL "Feta")

testing/fix_clang_nvcc_11.5.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#if defined(__NVCC__) && defined(__clang__) && __CUDACC_VER_MAJOR__ == 11 &&                       \
+    __CUDACC_VER_MINOR__ <= 5
+
+#if defined(__NVCC_DIAG_PRAGMA_SUPPORT__)
+#  pragma nv_diag_suppress 3171
+#else
+#  pragma diag_suppress 3171
+#endif
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wkeyword-compat"
+
+// Clang has a builtin called `__is_signed`. Unfortunately, libstdc++ headers
+// use this name as an identifier. Clang has a workaround for that, it checks 
+// if `__is_signed` is `const static bool` as in libstdc++ headers and if so,
+// disables the intrinsic for the rest of the TU:
+// https://github.com/llvm/llvm-project/blob/f49b6afc231242dfee027d5da69734836097cd43/clang/lib/Parse/ParseDecl.cpp#L3552-L3566
+const static bool __is_signed = false;
+
+#pragma clang diagnostic pop
+#endif // defined(__NVCC__) && defined(__clang__) && __CUDACC_VER_MAJOR__ == 11 &&
+       //   __CUDACC_VER_MINOR__ <= 5

testing/unittest/CMakeLists.txt

@@ -18,4 +18,7 @@ foreach(thrust_target IN LISTS THRUST_TARGETS)
   target_link_libraries(${framework_target} PUBLIC ${thrust_target})
   target_include_directories(${framework_target} PRIVATE "${Thrust_SOURCE_DIR}/testing")
   thrust_clone_target_properties(${framework_target} ${thrust_target})
+
+  thrust_fix_clang_nvcc_build_for(${framework_target})
+
 endforeach()