Re: all-completions broken in 20.7.1?

[Richard Stallman <rms@gnu.org>]

    all-completions function returns scarry things: i started a naked emacs 
    with -q option, then just evaled (all-completions "" [foo] nil), result is:

The second argument should be an alist or an obarray or a function.
[foo] is not valid as any of those.


    Today, if I eval (using C-j) the following in *scratch*, I get:

	    ?S       => 83
	    ?SPC     => 83

I think this simply fails to notice that there were junk letters `PC'
after the expression that it read.

	    '(?SPC)  => (83 PC)

    but if I do
	    M-: ? S P C RET
    I get
	    list: Trailing garbage following expression

    so the current character syntax really is pretty obscure.

That does check for junk that it did not read.
The difference in behavior is simply that.

Since it is not reasonable practice to use a character constant
followed by a symbol and not put a space between, I think it would be
ok to define something like ?SPC.  But I am not sure we need to do
this.  If we do it, we should first release an Emacs version where
it is an error to write ?<LETTER><LETTER>.