Re: Bugs in newly added completion capabilities.

[Richard M. Stallman]

    I don't like the idea of adding "" at the beginning of a completion table.
    Here I have a good reason, which is that it changes the behavior:

       (try-completion "" '("aaa" "aab" "aac"))  => "aa"
       (try-completion "" '("" "aaa" "aab" "aac"))  => ""

Oops.  I suggested adding "" because I thought it would not change
the results.  Since that is not true, adding "" is not a solution.

The only real solution would be to add a first element that's neither
a symbol nor a string, nor a cons cell whose car is a symbol or a
string.  Such as 0 or [].  That is sort of ugly.  It would be cleaner
to say that lists of symbols can't be used at all.  As you've said,
that would be no great loss.

Let's recall how this came up: as a side effect of the change to allow
symbols as the car of cons cells in an alist.  We could allow symbols
when they come from the car of an element, and not allow them when
they don't come from there.

Any objections?