VCL usability: missing import gives standard error.

[lkarsten]

Issue: When writing VCL that is using a vmod, and the vmod isn't imported, the error message is vague.

Expected: A clear error message. This generic parse error looks the same as when you have non-breaking space, missing a closing bracket, and probably other syntax issues in your VCL. Not user friendly.

Suggested: "Are you missing an import?" or "You may need import cookie;"

$ ~/work/Varnish-Cache/bin/varnishd/varnishd -C -f `pwd`/foo.com.vcl
Message from VCC-compiler:
Expected an action, 'if', '{' or '}'
('/[[CUT]]/var/foo.com.vcl' Line 24 Pos 9)
        cookie.parse(req.http.cookie);
--------############------------------

Running VCC-compiler fail

git master.

[Dridi]

You may also get this generic error message for objects, for example if you comment out a new xxx = vmod.constructor() statement and forget to comment out an xxx.call() somewhere.

[nigoroll]

I'd just add (e.g. function, method call) after "action"

[fgsch]

What about prefixing it with unknown identifier "cookie" or something along those lines so it's easier to spot?