The MSVC CUDA build customizations before CUDA 9 would not explicitly
add the -x cu option when building. This caused .cpp and .c files
invoked with CudaCompile to be compiled as host code and not
cuda. Now when we detect CUDA < 9 we will explicitly add this
option to correct this bug.
The set of compile flags used for a target's C and C++ sources is based
on the linker language. By default this is always the C++ flags if any
C++ sources appear in the target, and otherwise the C flags. Therefore
we can define the `COMPILE_LANGUAGE` generator expression in
`INCLUDE_DIRECTORIES` to match the selected language.
This is not exactly the same as for other generators, but is the best VS
and Xcode can do. It is also sufficient for many use cases since the
set of include directories for C and C++ is frequently similar but may
be distinct from those for other languages like CUDA.
Fixes: #17435
The set of compile flags used for a target's C and C++ sources is based
on the linker language. By default this is always the C++ flags if any
C++ sources appear in the target, and otherwise the C flags. Therefore
we can define the `COMPILE_LANGUAGE` generator expression in
`COMPILE_DEFINITIONS` to match the selected language.
This is not exactly the same as for other generators, but is the best VS
and Xcode can do. It is also sufficient for many use cases since the
set of definitions for C and C++ is frequently similar but may be
distinct from those for other languages like CUDA.
Issue: #17435
Since commit v3.9.0-rc4~3^2~1 (VS: Fix target_compile_options for CUDA,
2017-06-21), the evaluation of `COMPILE_LANGUAGE` receives the proper
language. The set of compile flags used for a target's C and C++
sources is based on the linker language. By default this is always the
C++ flags if any C++ sources appear in the target, and otherwise the C
flags. Therefore we can define the `COMPILE_LANGUAGE` generator
expression in `COMPILE_OPTIONS` to match the selected language.
This is not exactly the same as for other generators, but is the best VS
can do. It is also sufficient for many use cases since the set of
allowed flags for C and C++ is almost the same in Visual Studio.
Furthermore, since the VS generator moves many of the flags to
declarative `.vcxproj` elements, it will automatically avoid passing
C++ flags for C sources.
Issue: #17435
Fix the VS generator to honor `COMPILE_OPTIONS` for CUDA. The exclusion
added by commit v3.9.0-rc1~431^2~7 (VS: Do not pass CUDA compile options
to C compiler, 2017-03-07) was correct but we need additional logic to
pass the CUDA compile options to the CUDA compiler. Also we should
still pass the CXX or C options to MSVC (ClCompile) when those languages
are enabled even if the link language is CUDA.
CUDA 8.0 MSBuild rules do not pass `-x cu` to nvcc and so cannot support
a custom file extension. Fix our test for this to use a `.cu` extension
instead.
