Include clang system include dir

[ysbaddaden]

I failed to convert a C header with a reference to limits.h, because it eventually #include_next the compiler's own limits.h which can't be found.

I think crystal_lib should add this folder automatically to it's search path. The default place, as per the clang tooling documentation, is $(dirname $(which clang-3.5))/../lib/clang/3.5/include but different Linux distributions are putting them in different locations. See https://github.com/Rip-Rip/clang_complete/blob/master/plugin/libclang.py#L28 for example.

[luislavena]

@ysbaddaden could output from clang -print-search-dirs be used?

[ysbaddaden]

I found a solution: calling cc -E - -v </dev/null will print some informations about local paths, most notably the system include paths to search in order (and the default library paths, too).

It works perfectly on Ubuntu Linux with either GCC or clang.