PHP Dev Tools on Eclipse 3.8 Ubuntu - conflicting dependencies - eclipse

Question

I am trying to install PHP Development Tools in Eclipse 3.8 on Ubuntu. I have had several failed dependencies and I have managed to track them down and install them, notably as regards mylyn. Then when I installed org.eclipse.mylyn.context_feature.feature.group I get errors that are too complex for me to figure out.
Repository: http://download.eclipse.org/releases/luna
Package: PDT 3.4.0.201....
Here is what Eclipse tells me:
Cannot complete the install because of a conflicting dependency.
Software being installed: PHP Development Tools (PDT) 3.4.0.201502171754 (org.eclipse.php.feature.group 3.4.0.201502171754)
Software currently installed: Eclipse Platform 3.7.0.debbuild (org.eclipse.platform.ide 3.7.0.debbuild)
Only one of the following can be installed at once:
Bidirectional Text Support 0.10.0.v20130327-1442 (org.eclipse.equinox.bidi 0.10.0.v20130327-1442)
Bidirectional Text Support 0.9.0.dist (org.eclipse.equinox.bidi 0.9.0.dist)
Cannot satisfy dependency:
From: PHP Development Tools (PDT) 3.4.0.201502171754 (org.eclipse.php.feature.group 3.4.0.201502171754)
To: org.eclipse.php.ui [3.4.0.201502171754]
Cannot satisfy dependency:
From: PDT UI Plug-in 3.4.0.201502171754 (org.eclipse.php.ui 3.4.0.201502171754)
To: bundle org.eclipse.wst.common.frameworks.ui 0.0.0
Cannot satisfy dependency:
From: Eclipse Platform 3.8.1.dist-A8F8_IVRG4VZSCmeloKVfCrtIFotGyJZcMPL9 (org.eclipse.platform.feature.group 3.8.1.dist-A8F8_IVRG4VZSCmeloKVfCrtIFotGyJZcMPL9)
To: org.eclipse.rcp.feature.group [3.8.1.dist-8LA2GODFTJUDJ21934]
Cannot satisfy dependency:
From: Eclipse Platform 3.7.0.debbuild (org.eclipse.platform.ide 3.7.0.debbuild)
To: org.eclipse.platform.feature.group [3.8.1.dist-A8F8_IVRG4VZSCmeloKVfCrtIFotGyJZcMPL9]
Cannot satisfy dependency:
From: Eclipse RCP 3.8.1.dist-8LA2GODFTJUDJ21934 (org.eclipse.rcp.feature.group 3.8.1.dist-8LA2GODFTJUDJ21934)
To: org.eclipse.equinox.bidi [0.9.0.dist]
Cannot satisfy dependency:
From: WTP UI Plug-in 1.2.300.v201401292051 (org.eclipse.wst.common.frameworks.ui 1.2.300.v201401292051)
To: bundle org.eclipse.equinox.bidi [0.10.0,2.0.0)
Cannot satisfy dependency:
From: WTP UI Plug-in 1.2.300.v201401292115 (org.eclipse.wst.common.frameworks.ui 1.2.300.v201401292115)
To: bundle org.eclipse.equinox.bidi [0.10.0,2.0.0)
Any and all help appreciated.

Answer 1

If you want install eclipse pdt 3.4 on older eclipse releases you should use direct sites instead of simulates release update site:
PDT: http://download.eclipse.org/tools/pdt/updates/3.4 or http://download.eclipse.org/tools/pdt/updates/latest
DLTK 5.1.1: http://download.eclipse.org/technology/dltk/updates-dev/5.1.1/
After that you'll be able to install PDT 3.4 on eclipse 3.8

Answer 2

In the end the problem stemmed from trying to install a lot of stuff on an old version of Eclipse. This in turn stemmed from apt-get repositories that were not up-to-date. So when I tried to update my Eclipse I was told it was the latest version and I believed it, until greg-449 straightened me out.
Since I could not use apt-get or Ubuntu software centre (same thing) to install the latest Eclipse I just removed the installation and downloaded and unzipped Luna in a directory somewhere. I recommend this course of action if you are using Eclipse on Ubuntu.