I had a small working file with a main. I added a mult-line comment at the top of the file and forgot the ending */ . Careless error on my part which ended up giving you a "no main mainfest attribute" error when I ran it, but just was thinking that if there is no compilable code in a file it could potentially generate a warning, or, if a /* comment is never terminated before end of file, that could also be a warning.