GNU bug report logs - #22669
loading term/xterm.elc loads cl-lib at runtime

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Message #3 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: submit <at> debbugs.gnu.org
Subject: loading term/xterm.elc loads cl-lib at runtime
Date: Sun, 14 Feb 2016 17:57:00 -0500

Package: emacs
Version: 25.0.91

Loading term/xterm.elc loads cl-lib at runtime.
This means that cl-lib is loaded at startup in "emacs -Q -nw", which is
undesirable.

Apparently it's avoidable: http://debbugs.gnu.org/22613#63

    we'd have to pre-fill cl-generic's dispatcher cache with the specific
    dispatcher used (grep for cl--generic-prefill-dispatchers to see what
    that looks like).

Message #8 received at 22669 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Glenn Morris <rgm <at> gnu.org>
Cc: 22669 <at> debbugs.gnu.org
Subject: Re: bug#22669: loading term/xterm.elc loads cl-lib at runtime
Date: Mon, 15 Feb 2016 05:37:46 +0200

> From: Glenn Morris <rgm <at> gnu.org>
> Date: Sun, 14 Feb 2016 17:57:00 -0500
> 
> Loading term/xterm.elc loads cl-lib at runtime.
> This means that cl-lib is loaded at startup in "emacs -Q -nw", which is
> undesirable.

Why is that undesirable?

How is xterm.el different from any other package which requires
cl-lib?

Message #11 received at 22669 <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 22669 <at> debbugs.gnu.org
Subject: Re: bug#22669: loading term/xterm.elc loads cl-lib at runtime
Date: Mon, 15 Feb 2016 13:12:25 -0500

Eli Zaretskii wrote:

>> Loading term/xterm.elc loads cl-lib at runtime.
>> This means that cl-lib is loaded at startup in "emacs -Q -nw", which is
>> undesirable.
>
> Why is that undesirable?
>
> How is xterm.el different from any other package which requires
> cl-lib?

This was explained in http://debbugs.gnu.org/22613#45

Because we generally try to ensure that simply running "emacs -Q"
doesn't need any non-preloaded files to start up. lisp/term/xterm is
something of a corner case. Compare with term/x-win etc, which is
preloaded.

Also in this particular case, it can create the mistaken impression that
cl-lib is always available, which I think leads to some of the ongoing
confusion in bug#22613.

Message #14 received at 22669 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Glenn Morris <rgm <at> gnu.org>
Cc: 22669 <at> debbugs.gnu.org
Subject: Re: bug#22669: loading term/xterm.elc loads cl-lib at runtime
Date: Mon, 15 Feb 2016 21:55:59 +0200

> From: Glenn Morris <rgm <at> gnu.org>
> Cc: 22669 <at> debbugs.gnu.org
> Date: Mon, 15 Feb 2016 13:12:25 -0500
> 
> Eli Zaretskii wrote:
> 
> >> Loading term/xterm.elc loads cl-lib at runtime.
> >> This means that cl-lib is loaded at startup in "emacs -Q -nw", which is
> >> undesirable.
> >
> > Why is that undesirable?
> >
> > How is xterm.el different from any other package which requires
> > cl-lib?
> 
> This was explained in http://debbugs.gnu.org/22613#45

Sorry, I don't see any explanation there.  What I do see is the fact
that we treat lisp/term/* files specially.  I agree with that, since
these files are only loaded at startup when needed, so they are not
something "emacs -Q" "needs".

I also see there a suggestion to figure out why cl-lib gets loaded,
and I believe this part is now complete.

> Also in this particular case, it can create the mistaken impression that
> cl-lib is always available, which I think leads to some of the ongoing
> confusion in bug#22613.

OK, but that doesn't sound like a problem we need to fix in the code.

So my vote is not to fix this one.

Message #17 received at 22669 <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 22669 <at> debbugs.gnu.org
Subject: Re: bug#22669: loading term/xterm.elc loads cl-lib at runtime
Date: Tue, 16 Feb 2016 01:34:10 -0500

Eli Zaretskii wrote:

> these files are only loaded at startup when needed, so they are not
> something "emacs -Q" "needs".

term/xterm is needed in 90+% of -nw or without-X builds on GNU/Linux.
(Pulling a reasonable number from the air. All the terminal emulators
people actually use load term/xterm.)
So IME that counts as "effectively preloaded" and therefore makes this
something worth fixing.

Message #20 received at 22669 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Glenn Morris <rgm <at> gnu.org>
Cc: 22669 <at> debbugs.gnu.org
Subject: Re: bug#22669: loading term/xterm.elc loads cl-lib at runtime
Date: Tue, 16 Feb 2016 17:55:23 +0200

> From: Glenn Morris <rgm <at> gnu.org>
> Cc: 22669 <at> debbugs.gnu.org
> Date: Tue, 16 Feb 2016 01:34:10 -0500
> 
> > these files are only loaded at startup when needed, so they are not
> > something "emacs -Q" "needs".
> 
> term/xterm is needed in 90+% of -nw or without-X builds on GNU/Linux.
> (Pulling a reasonable number from the air. All the terminal emulators
> people actually use load term/xterm.)
> So IME that counts as "effectively preloaded" and therefore makes this
> something worth fixing.

Perhaps I don't understand the policy.  My interpretation of it is
that we preload stuff that is needed by 100% of builds during every
startup.  Under this interpretation, 90+% is not enough, especially
since there are also GUI sessions which don't need that at all.

So I don't think your observation convinces me, even if I agree with
your 90+% figure.  I don't think we should punish the rest of the
users by preloading a non-trivial amount of code they might never
need.

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