In reply to Meme.

It depends what they're actually doing. A 'producer' is the person who decides the creative and technical direction of the finished product with the product geared to their specifications. This can be anyone from the artist, to the songwriter to the manage or even an A&R who neither sings nor makes music but who just has great taste and an ear for what's hot. Producer is a separate job to songwriter though, however it is really for everyone involved to agree. That said, if you contribute neither lyric or melody then you shouldn't get 'songwriter' credit unless it is gifted to you (...like it is with Beyoncé).