Firstly, the Precise default version of
22.214.171.124-2ubuntu1, as noted at Ubuntu packages, so I'm not sure why you mention 1.7.4-3, as that is the 11.10 Oneiric default version. I should check whether you really are on Precise, or have upgraded properly.
The version you are using still has the
doxygen_direct_dot_run.diff patch applied, while the actual version for Precise, (126.96.36.199-2ubuntu1) doesn't have it applied. So using the real Precise version might solve some of the problems as it has other patches too. There aren't any current bugs describing your issue at Launchpad, so it could be a new one.
More generally, patches and changelogs
When you download the source (
apt-get source doxygen), you can see which patches are applied (for doxygen in Precise):
dpkg-source: info: applying manpages.diff dpkg-source: info: applying dot-config.diff dpkg-source: info: applying gcc-g.diff dpkg-source: info: applying doxygen-jquery.patch
However, you can also download the program's source without the patches being applied or the packages unpacked:
apt-get source doxygen --download-only
(You could build the package and omit some of the patches if you wanted to.)
If you have used the
--download-only switch to
apt-get source you will have 2 packages and a signature file. You can unpack
doxygen_188.8.131.52-2ubuntu1.debian.tar.gz to view the patches, changelog, and rules (not all the patches in the patches folder will actually be used).
The changelog will contain references to the patches and will always include the Debian (#number) or Launchpad (LP: #number) of the bug, and this can be searched on the respective bug trackers. That is the best way to find more information on the patches than in the very brief changelog.
Examples from the doxygen source changelog:
Don't apply doxygen_direct_dot_run.diff. Closes: #618125.
Now #618125 is the debian ticket, so you can search bugs by number at debian and find more details.
Add multiarch metadata to satisfy cross-dependencies (LP: #971739)
Similarly, to find more information you would search for this bug at Launchpad by entering the number.
More generally, you could also go to patches.ubuntu.com:
These patches are generated daily and contain the differences between an Ubuntu source package and the equivalent version of the same source in Debian.
Apart from discussion on the bug thread itself, on forums, or on irc channels, these avenues of investigation are about the most you can use to find out about the rationale for patches.