Re: emacs-lisp-mode highlights incorrectly defmacros/defuns’ arglists

[Garreau\, Alexandre]

On 2018-10-16 at 18:35, Alan Mackenzie wrote:
> On Tue, Oct 16, 2018 at 19:49:53 +0200, Garreau, Alexandre wrote:
>> At least *someone* must have *seen* this:
>> #+BEGIN_SRC elisp
>> (defmacro unless (cond &rest body)
>>   "If COND yields nil, do BODY, else return nil.
>> When COND yields nil, eval BODY forms sequentially and return
>> value of last one, or nil if there are none.
>
>> \(fn COND BODY...)"
>>   (declare (indent 1) (debug t))
>>   (cons 'if (cons cond (cons nil body))))
>> #+END_SRC
>
> You surely are conscious of the fact that `cond' is a special form?

I am, yet from the time it’s used as either a variable, or a macro arg,
normally that shouldn’t cause any issue… otherwise what’s the point of a
lisp-2, with 2 whole different namespaces?

> To use it as an argument name is asking for trouble, surely.

Still Emacs seems to use it extensively to mean “form evaluating to a
boolean” (different from “test” which is a function returning a
boolean), this nicely and understandably have the same as the most
primitive, old and handy special form taking those as arguments.

This exemple was an excerpt of subr.el.  And I noticed there that there
were many others.  As a probably quite old convention, this must trace
back to long ago so it must be disseminated all around emacs’ source
code.

Do you have any so better name to suggest for replacing the symbol
“cond” used as a variable everywhere in emacs’ source code?  because
otherwise I feel like it’s the fontification who’s wrong here.

> The font locking in emacs-lisp-mode appears not to be too
> sophisticated.  But it is fast.
>
>> Wouldn’t there be a way to turn off these highlightings in such
>> places of known old and fixed macro calls?
>
> There might well be, but it would slow fontification down, somewhat.
> I suspect that changing "cond" to something less contentious will get
> the result you want.

That much? Emacs source code using “cond” extensively, I’ve thought this
would be a must-have feature.  This always bugged me and I just re-saw
it so I thought about talking about it.