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bug#69108: false-positive warning "variable ‘_’ not left unused" in if-l
From: |
Michael Heerdegen |
Subject: |
bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let |
Date: |
Sat, 17 Feb 2024 23:02:07 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) |
Eli Zaretskii <eliz@gnu.org> writes:
> > Cc: 69108@debbugs.gnu.org
> > Date: Sat, 17 Feb 2024 01:28:55 +0100
> > From: Michael Heerdegen via "Bug reports for GNU Emacs,
> > the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> >
> > --- a/lisp/subr.el
> > +++ b/lisp/subr.el
> > @@ -2575,12 +2575,12 @@ delay-mode-hooks
> > (defun internal--build-binding (binding prev-var)
> > "Check and build a single BINDING with PREV-VAR."
> > (setq binding
> > - (cond
> > - ((symbolp binding)
> > + (pcase binding
> > + ((pred symbolp)
> > (list binding binding))
> > - ((null (cdr binding))
> > - (list (make-symbol "s") (car binding)))
> > - (t binding)))
> > + ((or `(,test) `(_ ,test))
> > + (list (make-symbol "s") test))
> > + (_ binding)))
>
> Thanks, but can we please leave this as 'cond', instead of converting
> it to a 'pcase'? It doesn't seem to be justified here, and even less
> so since you need to rewrite all the existing conditions.
Oh no.
If I don't rewrite this with `pcase', we would either artificially split
this case:
((or `(,test) `(_ ,test))
(list (make-symbol "s") test))
into two separate `cond' branches, or we had to merge them into a one branch
like this:
((or (null (cdr binding))
(eq '_ (car binding)))
(list (make-symbol "s")
(if (null (cdr binding))
(car binding)
(cadr binding))))
repeating a test. Is this what you prefer?
We could also move the test for _ to the beginning, destroying the logic
of the code. All of those alternatives seems worse wrt readability.
Please to everyone: let's avoid a new discussion about `pcase'. Please,
not again.
> > [My doc tweaks]
> This hunk seems to be unrelated?
Yes, I can make it a separate commit it drop it entirely if you prefer.
> And it is not necessarily for the better, IMO, at least not all of it
> (replaces active tense with passive, refills text that doesn't need
> refilling, and other minor issues,
I can try to improve that of course.
> like the confusing use of construct state in "last ELSE form").
Dunno what a "construct state" is. The doc missed to tell what `if-let'
returns when optional ELSE forms are omitted (which is allowed, and then
there is no last ELSE form return value), so I tried to add that. Did I
mess up the grammar?
Michael.
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Konstantin Kharlamov, 2024/02/13
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Michael Heerdegen, 2024/02/13
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Michael Heerdegen, 2024/02/16
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Eli Zaretskii, 2024/02/17
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Konstantin Kharlamov, 2024/02/17
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Ihor Radchenko, 2024/02/17
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Konstantin Kharlamov, 2024/02/17
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Ihor Radchenko, 2024/02/19
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Konstantin Kharlamov, 2024/02/19
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Michael Heerdegen, 2024/02/17
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let,
Michael Heerdegen <=
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Eli Zaretskii, 2024/02/18
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Michael Heerdegen, 2024/02/24
- bug#69108: false-positive warning "variable ‘_’ not left unused" in if-let* and if-let, Eli Zaretskii, 2024/02/25