Bug#485259: synfig: FTBFS when converted to new source format 3.0 (quilt): require -p0 for some patches

[Raphael Hertzog]

Package: synfig
Version: 0.61.08-3
Severity: wishlist
Usertags: 3.0-quilt-by-default

To prepare a possible switch to the new source package format "3.0
(quilt)" [1], I converted all source packages and tried to rebuild them.
Unfortunately, synfig failed, you can try yourself with those
commands (and dpkg-dev >= 1.14.19 [2]) :

$ apt-get source synfig
$ sed -i -e '/^Source:/ aFormat: 3.0 (quilt)' synfig-0.61.08/debian/control
$ dpkg-source -b synfig-0.61.08
$ dpkg-source -x synfig_0.61.08-3.dsc
$ cd synfig-0.61.08 && debuild -us -uc

In this process, if the .diff.gz contains changes to upstream files,
dpkg-source will have created a corresponding patch in
debian/patches/debian-changes-0.61.08-3 and will have registered that
patch in a quilt series (debian/patches/series, it is created if needed).
All the patches listed in the "series" file are applied directly during
the extraction (dpkg-source -x). quilt itself is used if available (and
will thus lead to the creation of the .pc directory), otherwise
dpkg-source applies the patches by itself. For more information about the
new source package format see the manual page dpkg-source(1).

In the case of synfig, it already uses quilt but some of the patches
require the '-p0' option of patch to be properly applied and this
option has been hardcoded in the series file. The new source package
format doesn't support this quilt feature and requires patches
to be applicable with the '-p1' option.

You can use the following command to easily update all the patches
that use the '-p0' option:
awk '{ if ($2 == "-p0") print $1 }' debian/patches/series | while read f; do perl -pi -e 's|^--- (?:\./)?|--- a/|; s|^\+\+\+ (?:\./)?|+++ b/|;' debian/patches/$f ; done

Not that you can replace "a" by "synfig-0.61.08.orig" and
"b" by "synfig-0.61.08" if you prefer.

Then don't forget to strip the "-p0" options from debian/patches/series.

As a side note, you must also pay attention to the following points in your
quilt usage to guarantee compatibility with the new source package
format:
- the patches must be in debian/patches/ together with the "series" file
  (you can use QUILT_PATCHES=debian/patches if needed)
- you should not override QUILT_PC to change the location of quilt's
  internal directory (".pc" by default)
- the patches should not reference absolute filenames (in +++/--- lines)
- your clean target must work even if the patches are already applied
- your build target must work with patches applied even if the clean
  target is supposed to unapply them (because dpkg-source -b might
  have applied them back)

Cheers,

[1] http://lists.debian.org/debian-devel-announce/2008/04/msg00004.html
[2] the upcoming dpkg-dev 1.14.20 is more tolerant with patches, you can
grab it here if you want to try with that version:
http://people.debian.org/~hertzog/packages/dpkg-dev_1.14.20_all.deb
-- 
Raphael Hertzog