[CMake] Building a Version Header

[Clark Gaebel]

I would like to generate file that looks something like this:

    // version.h
    #define VERSION "v0.1-345-ga77ede8"

where the version string is the result of running "git describe --tags
--dirty". How can I auto-generate this file, include it in my project,
and have it regenerate as a pre-build event?

-- 
Regards,
-Clark