elint and the byte-compiler

[Emanuel Berg]

I just did `elint-directory' on my 3964 lines
of Elisp.

The only warning it found was of the type:

    In top level expression:
    mail.el:46:Warning: Setting previously unbound symbol: read-mail-command

which was found countless of times.

This sounds sort of the same as the familiar warning
from the byte-compiler:

    ~/.emacs:25:7:Warning: assignment to free variable `tramp-verbose'

which can be muted either with

    (require 'tramp)

or

    (defvar tramp-verbose)

Questions:

Is there a difference between an unbound symbol and
a free variable? No? If so, why does the byte-compiler
react to some, but not nearly as many as elint? Is it
because the byte-compiler considers to context whereas
elint only the individual file? Is there any sense
muting the elint warnings as well with the same
method(s)? And what method is prefered, to `require'
or do the `defvar' hack? As for me, I'm fine loading
things when I need them first time (and then have them
loaded) only then if I set the variable before that,
is there a danger what is loaded will in it's own init
process write over what I already set?

-- 
underground experts united
http://user.it.uu.se/~embe8573