GNU bug report logs - #79382
patch needed after gnulib changed

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Package: diffutils;

Reported by: Bruno Haible <bruno <at> clisp.org>

Date: Wed, 3 Sep 2025 22:55:02 UTC

Severity: normal

Done: Paul Eggert <eggert <at> cs.ucla.edu>

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From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Bruno Haible <bruno <at> clisp.org>
Cc: 79382 <at> debbugs.gnu.org
Subject: bug#79382: commit e124541148d38cd8b7f962aceb72fb44e7cc0aab
Date: Tue, 9 Sep 2025 10:35:49 -0700
[Message part 1 (text/plain, inline)]
On 2025-09-08 00:13, Bruno Haible wrote:
> Paul Eggert wrote:
>> I meant to not worry about platforms where the "C" (not "C.utf8") locale
>> is multibyte. I don't know of how diffutils would misbehave in such
>> locales (other than not be strictly POSIX-conforming in unusual cases
>> where native tools aren't either), so I wanted Gnulib to not worry about
>> the possibility.
> 
> This possibility actually occurs on Android ≥ 5.0.

Yes, and if it causes a real problem in diffutils we should fix that as 
it comes up. I don't offhand know why it'd be a real problem.

>   * hard_locale_LC_TIME assumes that no locale, not even the en_US locale,
>     uses the same internal format string for "%c" as the C locale.

The assumption is a bit different: it's merely that only in the POSIX 
locale does "%c" produce that output for that particular date. Even if 
the other locale uses the same internal format string "%a %b %e %T %Y", 
in a non-English locale if it's quite likely they won't match POSIX's 
English-language abbreviations.

I don't know of any platform where hard_locale_LC_TIME incorrectly 
returns false. However, even if it does, diffutils' behavior will still 
be OK: it'll conform to POSIX and users will surely understand the 
output. And if a user complains about this extremely minor glitch I 
assume we can fix that as it comes up.

>        - the translator will not translate "(C)" by "(C)",
>        - the user does not use LANGUAGE with a precedence list.

Not quite following, but it's OK if in unusual cases the program outputs 
"(C)" when "©" would be better, so long as in ordinary cases "©" is 
output when it works, and so long as "©" is not output when it would 
display as gibberish.

>    * hard_locale_LC_MESSAGES assumes that
>        - diffutils.pot contains the strings from lib/version-etc.c
>          (which are now actually in gnulib.pot),

Yes, that's a problem, and thanks for mentioning it. It stems from quite 
a comedy of errors:

(a) diffutils' en translation is not installed.

(b) cmp looks in the wrong catalog for the "(C)" message.

(c) The gnulib.pot/gnulib.mo mechanism is not yet working widely even 
for packages other than diffutils. On current Fedora 42 if I run this 
shell command:

  LC_ALL=en_US.utf8 cat --version

although I see "Torbjörn" in UTF-8 as desired, I also see "Copyright (C) 
2025" which is wrong: it should be "Copyright © 2025". Worse, I see the 
exact same English message when I run this shell command:

  LC_ALL=fr_FR.utf8 cat --version

This is because even though 
/usr/share/locale/fr/LC_MESSAGES/coreutils.mo is installed, there is no 
file /usr/share/locale/fr/LC_MESSAGES/gnulib.mo, and Fedora does not 
supply a gnulib.mo file in any package that I can see. I reported this 
newish bug to Fedora yesterday 
<https://bugzilla.redhat.com/show_bug.cgi?id=2393892>.

(d) In response to that Fedora bug report, Lukáš Zaoral set in motion a 
fix. But he asked, "Since gnulib is meant to be bundled, how do you deal 
with the situation when the messages in the sources of the bundled
gnulib and gnulib-i10n differ? Do you have some upstream policy to make 
sure that they don't diverge?" Do we have an answer for that? I'm not 
sure myself.

(e) Even if Fedora started installing a gnulib.mo file, diffutils "make 
install" does not install such a file, so a standalone build of 
diffutils with './configure --prefix' would not work since it does not 
install gnulib.mo.


Given all this configuration mess, for now I took the following 
conservative approach in Diffutils.

(0) Update diffutils to use need-formatstring-macros when calling 
AM_GNU_GETTEXT. I discovered this issue while looking into the other 
problems. Perhaps need-formatstring-macros should be the only behavior 
nowadays? It hardly seems worth the hassle about worrying about older 
gettext versions.

(1) Change cmp's hard_locale_LC_MESSAGES to test via setlocale, not via 
gettext. setlocale should work fine if ENABLE_NLS is nonzero in Diffutils.

(2) Remove diffutils' po/en.po file. It is an unused revenant.

(3) Stick with the longstanding approach of having the Diffutils message 
catalog translate all messages, including those taken from Gnulib. This 
has worked for decades, translators are used to it, and the Gnulib part 
of the catalog hardly ever changes.

(4) Modify Gnulib to let Diffutils override the textdomain that Gnulib 
uses. Done via Gnulib commit 
<https://cgit.git.savannah.gnu.org/cgit/gnulib.git/commit/?id=2b2bcdbc3bf3de2838a4b5051e32366e9a94f1e3>.

(5) Use this new Gnulib feature in Diffutils.

I installed the attached patches to Diffutils to do this.

An alternative to (4) and (5) would be to let config.h specify the "_" 
macro, and have Gnulib define this macro only if it is not already 
defined. This would make for slightly smaller executables. However, it 
would be brittler and more intrusive. Or perhaps you can think of a 
better way to do what is wanted in (3).
[0001-maint-use-need-formatstring-macros.patch (text/x-patch, attachment)]
[0002-cmp-improve-LC_MESSAGES-test.patch (text/x-patch, attachment)]
[0003-maint-remove-po-en.po.patch (text/x-patch, attachment)]
[0004-build-update-gnulib-submodule-to-latest.patch (text/x-patch, attachment)]
[0005-maint-use-our-textdomain-for-Gnulib.patch (text/x-patch, attachment)]

This bug report was last modified 3 days ago.

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