[CMake] Support for Custom LANG in CMAKE (CUDA and general case)

[Łukasz Tasz]

Hi all,

>
> Other than the 'more elegant' prospect of being able to just put .cu files
> into a target, is there anything else deficient about the current FindCUDA
> macros?  All you have to do really is to use cuda_add_executable instead of
> add_executable.
>

As far as I understood the topic aim is to provide object compiled
with different language - in this case with CUDA.
But respecting dependencies that are visible on all platform. Since
*.cu files are like C++ syntax, same dependency generator from cmake
can be used.

The aim is to provide add_executable(demo main.cxx demo1.cu demo2.cu)
or  add_executable(demo main.cu demo1.cu demo2.cu),
The first example will be only partialy compiled by CUDA.


> I've iterated with Peter many times about his proposed changes, and one of
> the issues we were hoping to solve is the ability to target different output
> formats.  CUDA supports generation of not only object files, but PTX and
> CUBIN files which need to not be treated as an object file.  In addition, it
> wasn't clear how this adaptation would behave along side the existing
> FindCUDA behavior for which we have to be backward compatible with.

In this case cmake gives very flexible way of introducing new
language, just  correctly initialise all *<LANG>* variables,
But one very important thing is gone, dependencies. There is no
interface how to provide dependencies / generate dependencies for
cmake. (at least I don't know - making macro that will ccan the files
for #includes and calling add_dependencies is not a solution)

It would be really nice to have this language included, or even more
flexible solution is also welcome, to get intercafe to impement own
dependency scaner or inherit current one (C/CXX)


regards
Lukasz Tasz