nDmitry/grunt-autoprefixer — pull request #42 by shakyShane (2014-04-26 14:20:24+00:00)
Title: Added a warning if no source files were found. Stops silent failure.

Filtering over `f.src` when the array length is `0` causes silent failure of this task.

Grunt already ensures that you only have access to existing files in `this.files`, so a simple simple check on the length of `f.src` is enough here to give useful feedback to a user.