CUDA: forward unknown flags to host compiler when possible.

Starting with CUDA 10.2 the nvcc compiler has gained support
to automatically forward unknown flags to the host compiler.

This behavior is highly desired as projcts that mix CUDA, C, C++
run into situation where flags such as `-pthread` which aren't
supported by nvcc, are being applied to all source files and
therefore break CUDA compilation.

3 files changed, 29 insertions, 28 deletions

diff --git a/Modules/CMakeCUDAInformation.cmake b/Modules/CMakeCUDAInformation.cmake
index b0d80d1..e140808 100644
--- a/Modules/CMakeCUDAInformation.cmake
+++ b/Modules/CMakeCUDAInformation.cmake
@@ -93,9 +93,7 @@ include(CMakeCommonLanguageInclude)
 # CMAKE_CUDA_LINK_EXECUTABLE
 
 if(CMAKE_CUDA_HOST_COMPILER)
-  set(CMAKE_CUDA_HOST_FLAGS "-ccbin=<CMAKE_CUDA_HOST_COMPILER>")
-else()
-  set(CMAKE_CUDA_HOST_FLAGS "")
+  string(APPEND _CMAKE_CUDA_EXTRA_FLAGS " -ccbin=<CMAKE_CUDA_HOST_COMPILER>")
 endif()
 
 set(__IMPLICT_LINKS )
@@ -135,24 +133,24 @@ endif()
 #Specify how to compile when ptx has been requested
 if(NOT CMAKE_CUDA_COMPILE_PTX_COMPILATION)
   set(CMAKE_CUDA_COMPILE_PTX_COMPILATION
-    "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -ptx <SOURCE> -o <OBJECT>")
+    "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -ptx <SOURCE> -o <OBJECT>")
 endif()
 
 #Specify how to compile when separable compilation has been requested
 if(NOT CMAKE_CUDA_COMPILE_SEPARABLE_COMPILATION)
   set(CMAKE_CUDA_COMPILE_SEPARABLE_COMPILATION
-    "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -dc <SOURCE> -o <OBJECT>")
+    "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -dc <SOURCE> -o <OBJECT>")
 endif()
 
 #Specify how to compile when whole compilation has been requested
 if(NOT CMAKE_CUDA_COMPILE_WHOLE_COMPILATION)
   set(CMAKE_CUDA_COMPILE_WHOLE_COMPILATION
-    "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -c <SOURCE> -o <OBJECT>")
+    "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -c <SOURCE> -o <OBJECT>")
 endif()
 
 if(CMAKE_GENERATOR STREQUAL "Ninja")
   set(CMAKE_CUDA_COMPILE_DEPENDENCY_DETECTION
-    "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -M <SOURCE> -MT <OBJECT> -o $DEP_FILE")
+    "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -M <SOURCE> -MT <OBJECT> -o $DEP_FILE")
   #The Ninja generator uses the make file dependency files to determine what
   #files need to be recompiled. Unfortunately, nvcc doesn't support building
   #a source file and generating the dependencies of said file in a single
@@ -171,13 +169,6 @@ if(NOT CMAKE_CUDA_LINK_EXECUTABLE)
     "<CMAKE_CUDA_HOST_LINK_LAUNCHER> <LINK_FLAGS> <OBJECTS> -o <TARGET> <LINK_LIBRARIES>${__IMPLICT_LINKS}")
 endif()
 
-if( CMAKE_CUDA_COMPILER_ID STREQUAL "NVIDIA" AND
-    CMAKE_CUDA_COMPILER_VERSION VERSION_GREATER_EQUAL "8.0.0")
-  set(_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS "-Wno-deprecated-gpu-targets")
-else()
-  set(_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS "")
-endif()
-
 # Add implicit host link directories that contain device libraries
 # to the device link line.
 set(__IMPLICT_DLINK_DIRS ${CMAKE_CUDA_IMPLICIT_LINK_DIRECTORIES})
@@ -192,14 +183,15 @@ foreach(dir ${__IMPLICT_DLINK_DIRS})
 endforeach()
 unset(__IMPLICT_DLINK_DIRS)
 
+
 #These are used when linking relocatable (dc) cuda code
 if(NOT CMAKE_CUDA_DEVICE_LINK_LIBRARY)
   set(CMAKE_CUDA_DEVICE_LINK_LIBRARY
-    "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <LANGUAGE_COMPILE_FLAGS> ${CMAKE_CUDA_COMPILE_OPTIONS_PIC} ${_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS} -shared -dlink <OBJECTS> -o <TARGET> <LINK_LIBRARIES>${__IMPLICT_DLINK_FLAGS}")
+    "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <LANGUAGE_COMPILE_FLAGS> ${CMAKE_CUDA_COMPILE_OPTIONS_PIC} ${_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS} -shared -dlink <OBJECTS> -o <TARGET> <LINK_LIBRARIES>${__IMPLICT_DLINK_FLAGS}")
 endif()
 if(NOT CMAKE_CUDA_DEVICE_LINK_EXECUTABLE)
   set(CMAKE_CUDA_DEVICE_LINK_EXECUTABLE
-    "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <FLAGS> ${CMAKE_CUDA_COMPILE_OPTIONS_PIC} ${_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS} -shared -dlink <OBJECTS> -o <TARGET> <LINK_LIBRARIES>${__IMPLICT_DLINK_FLAGS}")
+    "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <FLAGS> ${CMAKE_CUDA_COMPILE_OPTIONS_PIC} ${_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS} -shared -dlink <OBJECTS> -o <TARGET> <LINK_LIBRARIES>${__IMPLICT_DLINK_FLAGS}")
 endif()
 
 unset(_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS)
diff --git a/Modules/Compiler/NVIDIA-CUDA.cmake b/Modules/Compiler/NVIDIA-CUDA.cmake
index b59deda..2400a9d 100644
--- a/Modules/Compiler/NVIDIA-CUDA.cmake
+++ b/Modules/Compiler/NVIDIA-CUDA.cmake
@@ -2,6 +2,22 @@ set(CMAKE_CUDA_COMPILER_HAS_DEVICE_LINK_PHASE True)
 set(CMAKE_CUDA_VERBOSE_FLAG "-v")
 set(CMAKE_CUDA_VERBOSE_COMPILE_FLAG "-Xcompiler=-v")
 
+if (NOT CMAKE_CUDA_COMPILER_VERSION VERSION_LESS 10.2)
+  # The -forward-unknown-to-host-compiler flag was only
+  # added to nvcc in 10.2 so before that we had no good
+  # way to invoke the CUDA compiler and propagate unknown
+  # flags such as -pthread to the host compiler
+  set(_CMAKE_CUDA_EXTRA_FLAGS "-forward-unknown-to-host-compiler")
+else()
+  set(_CMAKE_CUDA_EXTRA_FLAGS "")
+endif()
+
+if(CMAKE_CUDA_COMPILER_VERSION VERSION_GREATER_EQUAL "8.0.0")
+  set(_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS "-Wno-deprecated-gpu-targets")
+else()
+  set(_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS "")
+endif()
+
 if(NOT "x${CMAKE_CUDA_SIMULATE_ID}" STREQUAL "xMSVC")
   set(CMAKE_CUDA_COMPILE_OPTIONS_PIE -Xcompiler=-fPIE)
   set(CMAKE_CUDA_COMPILE_OPTIONS_PIC -Xcompiler=-fPIC)
diff --git a/Modules/Platform/Windows-NVIDIA-CUDA.cmake b/Modules/Platform/Windows-NVIDIA-CUDA.cmake
index 94d77b9..30b5aa9 100644
--- a/Modules/Platform/Windows-NVIDIA-CUDA.cmake
+++ b/Modules/Platform/Windows-NVIDIA-CUDA.cmake
@@ -1,11 +1,11 @@
 include(Platform/Windows-MSVC)
 
 set(CMAKE_CUDA_COMPILE_PTX_COMPILATION
-  "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -ptx <SOURCE> -o <OBJECT> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS")
+  "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -ptx <SOURCE> -o <OBJECT> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS")
 set(CMAKE_CUDA_COMPILE_SEPARABLE_COMPILATION
-  "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -dc <SOURCE> -o <OBJECT> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS")
+  "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -dc <SOURCE> -o <OBJECT> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS")
 set(CMAKE_CUDA_COMPILE_WHOLE_COMPILATION
-  "<CMAKE_CUDA_COMPILER> ${CMAKE_CUDA_HOST_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -c <SOURCE> -o <OBJECT> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS")
+  "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <DEFINES> <INCLUDES> <FLAGS> -x cu -c <SOURCE> -o <OBJECT> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS")
 
 set(__IMPLICT_LINKS )
 foreach(dir ${CMAKE_CUDA_HOST_IMPLICIT_LINK_DIRECTORIES})
@@ -30,11 +30,6 @@ set(CMAKE_CUDA_LINK_EXECUTABLE
 unset(_CMAKE_VS_LINK_EXE)
 unset(_CMAKE_VS_LINK_EXE)
 
-if(CMAKE_CUDA_COMPILER_VERSION VERSION_GREATER_EQUAL "8.0.0")
-  set(_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS "-Wno-deprecated-gpu-targets")
-else()
-  set(_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS "")
-endif()
 
 # Add implicit host link directories that contain device libraries
 # to the device link line.
@@ -51,11 +46,9 @@ endforeach()
 unset(__IMPLICT_DLINK_DIRS)
 
 set(CMAKE_CUDA_DEVICE_LINK_LIBRARY
-  "<CMAKE_CUDA_COMPILER> <LANGUAGE_COMPILE_FLAGS> ${_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS} -shared -dlink <OBJECTS> -o <TARGET> <LINK_LIBRARIES> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS${__IMPLICT_DLINK_FLAGS}")
+  "<CMAKE_CUDA_COMPILER> ${_CMAKE_CUDA_EXTRA_FLAGS} <LANGUAGE_COMPILE_FLAGS> ${_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS} -shared -dlink <OBJECTS> -o <TARGET> <LINK_LIBRARIES> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS${__IMPLICT_DLINK_FLAGS}")
 set(CMAKE_CUDA_DEVICE_LINK_EXECUTABLE
-  "<CMAKE_CUDA_COMPILER> <FLAGS> ${_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS} -shared -dlink <OBJECTS> -o <TARGET> <LINK_LIBRARIES> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS${__IMPLICT_DLINK_FLAGS}")
-
-unset(_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS)
+  "<CMAKE_CUDA_COMPILER>  ${_CMAKE_CUDA_EXTRA_FLAGS} <FLAGS> ${_CMAKE_CUDA_EXTRA_DEVICE_LINK_FLAGS} -shared -dlink <OBJECTS> -o <TARGET> <LINK_LIBRARIES> -Xcompiler=-Fd<TARGET_COMPILE_PDB>,-FS${__IMPLICT_DLINK_FLAGS}")
 unset(__IMPLICT_DLINK_FLAGS)
 
 string(REPLACE "/D" "-D" _PLATFORM_DEFINES_CUDA "${_PLATFORM_DEFINES}${_PLATFORM_DEFINES_CXX}")