Invalid expression assignment is not detected by analyser

[lerno]

This code is accepted by the analyser but is not valid C.

a = argc + 1 = 1;

[bvdberg]

Indeed. We have to extend the analyses to check for these situations. What these 'situations'
are exactly I'm not sure about.

[lerno]

I have a pretty good idea, but it touches code that is affected by the open pull requests, so any fixes need to wait.