make distcheck fails for non-GNU packages using libtool, gettext, automake, and address@hidden

[Andrew Suffield]

This little clusterfuck has taken *hours* to track down. It only
occurs in the precise scenario listed in the subject - a non-GNU
package that uses all three, and that generates an address@hidden po file (or
address@hidden).

[I'm fairly sure this is belongs to either libtool or gettext (you
have to read all the way to the bottom to find where libtool comes
in). Sending it to bug-automake as an FYI rather than a bug]

The basic symptom is that distcheck fails in po/, while trying to
update the address@hidden,}quot.po files, because automake has arranged
things so that it cannot write to the source directory, and the
Makefile.in.in from gettext wants to update the po files in the source
directory.

[
Background:
Automake's distcheck magic lays things out like this:
Source package is unpacked into $package-$version/
The package is configured and built in $package-$version/=build/
]

Normally, po/Makefile will not update the po files unless they have
changed from the source directory. Further investigation revealed that
the address@hidden file in the source directory had comments like:
# English translations for GNU foo package.
While the one in =build/po had this:
# English translations for foo package.

This comes from msginit, which fills in the package name
automatically. The name is acquired by
/usr/lib/gettext/project-id. project-id determines whether or not a
package is a GNU package by grepping the directory that contains
'configure' for files with the string "GNU $package" in them.

Libtool's autoconf macros insert this comment into the libtool script:
# Generated automatically by  (GNU $package $version)

This causes the GNU detection in project-id to misfire, so the po
files get incorrect headers (it is likely that other projects have
acquired incorrect headers in their po files from this).

(Incidentally, that should have said "Generated automatically by
configure"; something else is wrong with libtool)

When distcheck is running, libtool goes into =build/ instead of the
source directory, so project-id never sees it, so when msginit
regenerates address@hidden in =build/po, it no longer thinks it is a GNU
project, so the files differ and the build fails.

Phew.

Libtool probably shouldn't be suggesting that all the world is a GNU
project, and gettext probably shouldn't be using a mechanism quite so
unreliable to figure it out (maybe something in Makevars instead?).

-- 
  .''`.  ** Debian GNU/Linux ** | Andrew Suffield
 : :' :  http://www.debian.org/ | Dept. of Computing,
 `. `'                          | Imperial College,
   `-             -><-          | London, UK

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