Parse language field in YAML

[robertodr]

Parse language field in YAML to generate project(<PROJECT_NAME <PROJECT_LANGUAGE>) in CMakeLists.txt

Why? Delayed enabling of languages within the cc.cmake, cxx.cmake and fc.cmake causes CMake to load C and C++ as default languages for a project. This is in principle unnecessary for a project that only needs one language. The "only one language" behavior can be enforced by setting the language when declaring the project.

Questions

• [x] This line uses a ternary if to check whether a list of languages or a single language was given. It might not be exactly the most readable piece of code.

• [x] The enable_language in cc.cmake, cxx.cmake and fc.cmake is probably redundant.

• [x] Ready to go

[bast]

Interesting. I did not know there was a difference between declaring a language with project or enable_language. I liked that the language was defined in one place and this is now lost but I think your suggestion is better although one could now declare Fortran in the YAML and then include C via the module.

The ternary is a bit terse but I can then expand it and add a comment.

Indeed the enable_language is now redundant.

Do the broken tests have anything to do with this PR? You mentioned over coffee that this might need more testing or was this something else?

[robertodr]

I did not know either. It came as a big surprise that for a Fortran-only project both the C and C++ compiler were searched for before the Fortran compiler. I think this need documenting inside Autocmake, i.e. that the language is set in the YAML file and in a module. If you don't have time writing docs, hold off merging until I can.

By the way, the language field in the YAML is now compulsory.

[robertodr]

The fc_omp test is broken, as it seems CMake checks for the C OpenMP flag even though the language is not defined. I am puzzled by the fact that the if(DEFINED CMAKE_<LANG>_COMPILER_ID) checks are in place and should avoid these scenarios...

[bast]

I cannot reproduce the problem locally. I will check whether this is linked to the CMake version.

[bast]

Can you please update your branch with latest changes on upstream master? Now testing CMake 3.8.0 instead of an arcane 2.8. Hopefully this will resolve the problem.

[robertodr]

Apologies for slow response. Fortran tests cases are failing Mac OS X.

[bast]

No problem - if somebody is slow then it's me. Just for my reference saving your good suggestion: "Try using a layer xcode image 7.3".

[robertodr]

And it worked! I think you can ignore the older XCode version on Travis. I will rebase and squash some of the commits so you get a cleaner history.

[bast]

Awesome! Thank you so much for this important change and also for your patience with this.