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From: Michael Albinus <michael.albinus@gmx.de>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: emacs-devel@gnu.org
Subject: Re: Cleaning up code
Date: Thu, 15 Aug 2013 10:40:38 +0200	[thread overview]
Message-ID: <87mwojiby1.fsf@gmx.de> (raw)
In-Reply-To: <jwvd2phimkh.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Tue, 13 Aug 2013 12:30:47 -0400")

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> However, setting `byte-compile-force-lexical-warnings' to t is too
>> coarse. For example, Tramp's macro `with-parsed-tramp-file-name'
>> let-binds several variables "just in case". They are reported as unused
>> then, on every invocation of that macro.
>
> Yup, that's one of the main problems: when a single let in the source
> ends up duplicated after expansion so some expansions may use it while
> others end up not using it.
>
> We need to add some way to tell Emacs that it should check "the sum of
> all uses" or something like that.  In your case, this "sum" is
> open-ended, so we should instead just tell it not to check at all.

Yep.

There is also another case where it doesn't work as expected. Often, I
let bind a variable for side effect, like this:

      (let ((default-directory (tramp-compat-temporary-file-directory))
            (outline-regexp tramp-debug-outline-regexp))
        (outline-mode))

And I get from the byte compiler

tramp.el:1400:1:Warning: Unused lexical variable `outline-regexp'

In Tramp, there are many such stanzas of intended side effect
bindings. Therefore, there are too many false positives, that I could
see the real warnings I should fix.

Could we have a byte-compiler option telling that such bindings are
intended? Something like this:

      (let ((byte-compile-force-lexical-warnings nil)
            (default-directory (tramp-compat-temporary-file-directory))
            (outline-regexp tramp-debug-outline-regexp))
        (outline-mode))

>         Stefan

Best regards, Michael.



  reply	other threads:[~2013-08-15  8:40 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-07 15:57 Cleaning up code Stefan Monnier
2013-08-13 15:17 ` Michael Albinus
2013-08-13 16:30   ` Stefan Monnier
2013-08-15  8:40     ` Michael Albinus [this message]
2013-08-15 14:37       ` Stefan Monnier
2013-08-15 17:05         ` Michael Albinus

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