If I edit a file like the following:

(defpackage :foo (:use :cl))

(in-package :foo)

...more core...

before the DEFPACKAGE has been evaluated, symbol completion doesn't work in the file -- nor does much anything.

I can't even C-c C-c the DEFPACKAGE, because that part of the file is taken to be in FOO as well.

So, two suggestions:

* If there is an IN-PACKAGE form, assume the part of the file above it is in CL-USER.

* If there is an IN-PACKAGE form, but the package doesn't exist, assume the whole file is in CL-USER.

Cheers,

-- Nikodemus