[test-suite] Check that we can use std::shared_future from CUDA host code.

[jlebar]

Summary

This checks for the clang bug fixed in https://reviews.llvm.org/D24407.

[tra]

LGTM

test-suite/trunk/External/CUDA/CMakeLists.txt

macro(create_one_local_test Name FileGlob)
   endif()
   list(APPEND VARIANT_CUDA_TESTS ${_target})
 endmacro()
 
 # Create targets for CUDA tests that are part of the test suite.
 macro(create_local_cuda_tests VariantSuffix)
   create_one_local_test(axpy axpy.cu)
   create_one_local_test(empty empty.cu)
+  create_one_local_test(future future.cu)
 endmacro()
 
 macro(thrust_make_test_name TestName TestSourcePath)
   string(REPLACE "${THRUST_PATH}/testing/" "" _tmp ${TestSourcePath})
   string(REPLACE "/" "-" _tmp ${_tmp})
   string(REPLACE "<" "_" _tmp ${_tmp})
   string(REPLACE ">" "_" _tmp ${_tmp})
   string(REGEX REPLACE "\.(cpp|cu)$" "" _tmp ${_tmp})

test-suite/trunk/External/CUDA/future.cu

+// Make sure that we can compile CUDA files that include <future> and use
+// std::shared_future.
+//
+// At one point in time this didn't work because clang defined different values
+// for __GCC_ATOMIC_INT_LOCK_FREE on host and device.  This caused libstdc++
+// not to define std::shared_future when compiling for device, resulting in
+// compile errors (even though we only use std::shared_future in host code).
+
+#if __cplusplus >= 201103L
+#include <future>
+
+void foo() {
+  std::shared_future<int> x;
+}
+#else
+#warning Skipping test because not compiled in C++11 mode.
+#endif
+
+int main() {
+  return 0;
+}