Re: Timestamps in ...-autoloads.el files

[ludo@gnu.org (Ludovic Courtès)]

Alex Kost <alezost@gmail.com> skribis:

> Ludovic Courtès (2016-05-16 15:45 +0300) wrote:
>
>> Alex Kost <alezost@gmail.com> skribis:
> [...]
>>> I looked at the compiled "autoload.elc" file and if I understood it
>>> correctly, it was compiled using the unpatched version of "autoload.el"
>>> (because there is no mention of SOURCE_DATE_EPOCH there).
>>
>> Indeed.
>>
>>> But I don't understand how it could happen since patching is performed
>>> before building.  Any ideas?
>>
>> I think I have one:
>>
>> $ git describe
>> v0.10.0-798-g8a7680a
>> $ tar tvf $(./pre-inst-env guix build -S emacs) |grep 'autoload\.el'
>> -rw-r--r-- root/root     37292 1970-01-01 01:00 emacs-24.5/lisp/emacs-lisp/autoload.el
>> -rw-r--r-- root/root     37127 1970-01-01 01:00 emacs-24.5/lisp/emacs-lisp/autoload.el.orig
>> -rw-r--r-- root/root     22624 1970-01-01 01:00 emacs-24.5/lisp/emacs-lisp/autoload.elc
>>
>> Upstream’s tarball already includes those three files.
>
> IIUC this source is after applying our patches (including
> "emacs-source-date-epoch.patch"):
>
> - “autoload.el.orig” is the original file from the upstream;

Indeed, this one isn’t present in upstream’s tarball:

--8<---------------cut here---------------start------------->8---
$ wget -q -O - ftp://ftp.gnu.org/gnu/emacs/emacs-24.5.tar.xz | tar tJvf - | grep 'autoload\.'
-rw-rw-r-- nico/nico     37127 2015-04-02 09:23 emacs-24.5/lisp/emacs-lisp/autoload.el
-rw-r--r-- nico/nico     22624 2015-04-08 19:16 emacs-24.5/lisp/emacs-lisp/autoload.elc
--8<---------------cut here---------------end--------------->8---

How come we’re introducing this one?  I thought ‘patch’ did not produce
.orig files unless the patch failed to apply, but here the patch
correctly applies, only with a small offset (can be seen by running
‘guix build -S emacs --check’):

--8<---------------cut here---------------start------------->8---
patching file lisp/loadup.el
patching file lisp/emacs-lisp/autoload.el
Hunk #1 succeeded at 361 (offset -17 lines).
--8<---------------cut here---------------end--------------->8---

Apparently we have to use ‘--no-backup-if-mismatch’ to avoid that.

> Thanks, the mystery is solved now.  This is an unpleasant surprise, I
> didn't know that emacs release comes with the compiled files.

Yeah.  :-/

Ludo’.