Adding CUDA NVCC build (#365)

* Adding CUDA build

* Filter NVCC warning

* Constexpr reword

.github/workflows/tests.yml

@@ -22,3 +22,20 @@ jobs:
         path: ~/.cache/pre-commit
         key: pre-commit|${{ env.PY }}|${{ hashFiles('.pre-commit-config.yaml') }}
     - uses: pre-commit/action@v1.0.0
+
+  cuda-build:
+    name: CUDA build only
+    runs-on: ubuntu-latest
+    container: nvidia/cuda:10.2-devel-ubuntu18.04
+    steps:
+      - uses: actions/checkout@v1
+        with:
+          submodules: true
+      - name: Add wget
+        run: apt-get update && apt-get install -y wget
+      - name: Install Modern CMake
+        run: wget -qO- "https://cmake.org/files/v3.16/cmake-3.16.0-Linux-x86_64.tar.gz" | tar --strip-components=1 -xz -C /usr/local
+      - name: Configure
+        run: cmake -S . -B build -DCLI11_CUDA_TESTS=ON
+      - name: Build
+        run: cmake --build build

CMakeLists.txt

@@ -45,6 +45,14 @@ if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
     set(CMAKE_CXX_EXTENSIONS OFF)
     set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
+    option(CLI11_CUDA_TESTS "Build the tests with NVCC to check for warnings there - requires CMake 3.9+")
+    if(CLI11_CUDA_TESTS)
+        enable_language(CUDA)
+
+        # Print out warning and error numbers
+        set(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} -Xcudafe --display_error_number")
+    endif()
+
     option(CLI11_WARNINGS_AS_ERRORS "Turn all warnings into errors (for CI)")
 
     # Be moderately paranoid with flags

include/CLI/TypeTools.hpp

@@ -140,7 +140,17 @@ struct pair_adaptor<
 // check for constructibility from a specific type and copy assignable used in the parse detection
 template <typename T, typename C> class is_direct_constructible {
     template <typename TT, typename CC>
-    static auto test(int, std::true_type) -> decltype(TT{std::declval<CC>()}, std::is_move_assignable<TT>());
+    static auto test(int, std::true_type) -> decltype(
+// NVCC warns about narrowing conversions here
+#ifdef __CUDACC__
+#pragma diag_suppress 2361
+#endif
+        TT { std::declval<CC>() }
+#ifdef __CUDACC__
+#pragma diag_default 2361
+#endif
+        ,
+        std::is_move_assignable<TT>());
 
     template <typename TT, typename CC> static auto test(int, std::false_type) -> std::false_type;
 

tests/CMakeLists.txt

@@ -52,10 +52,20 @@ set(CLI11_MULTIONLY_TESTS
 include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 
 foreach(T ${CLI11_TESTS})
+    if(CLI11_CUDA_TESTS)
+        set_property(
+            SOURCE ${T}.cpp
+            PROPERTY
+            LANGUAGE CUDA
+        )
+    endif()
 
     add_executable(${T} ${T}.cpp ${CLI11_headers})
     add_sanitizers(${T})
-    target_link_libraries(${T} PUBLIC CLI11 CLI11_warnings)
+    target_link_libraries(${T} PUBLIC CLI11)
+    if(NOT CLI11_CUDA_TESTS)
+        target_link_libraries(${T} PUBLIC CLI11_warnings)
+    endif()
     add_gtest(${T})
 
     if(CLI11_SINGLE_FILE AND CLI11_SINGLE_FILE_TESTS)

tests/SetTest.cpp

@@ -306,7 +306,7 @@ TEST_F(TApp, SimiShortcutSets) {
 }
 
 TEST_F(TApp, SetFromCharStarArrayVector) {
-    constexpr const char *names[] = {"one", "two", "three"};
+    constexpr const char *names[3]{"one", "two", "three"};
     std::string value;
     auto opt = app.add_option("-s,--set", value)
                    ->check(CLI::IsMember{std::vector<std::string>(std::begin(names), std::end(names))});