lunaryorn/flycheck — pull request #86 by kwitek (2013-02-17 19:34:11+00:00)
Title: Add evaluation support in flycheck-substitute-argument

Use special symbol eval in the argument list to allow evaluation of
arbitrary form, necessary to calculate checker arguments.

I need this feature for xbuild (Mono/.Net project building) checker, that runs build for project containing file and not for source file itself.
https://github.com/kwitek/csmart/blob/master/flycheck-xbuild.el