Eclipse / Android : "Errors running builder 'Android Pre Compiler' on project..."

For those of you who don't want to install preview version of ADT, there is a workaround described here.

1. Open properties of project in Eclipse then Resources -> Resource filters.
2. Click the "Add..." button -> Check "Exclude all", "Files and folders", "All children". In the text entry box input ".svn" (without quotes).
3. Restart Eclipse.

I had the same problem with .git folder, it worked like a charm.

I always hate answering my own questions, but this is a genuine solution.

The 21.0.1 version of the ADT tools has a bug that prevents a project building if you have any files without extensions in them. This is a particular problem for users (like me) using subversion with has extension-less files.

One recommended solution is to install these 'subversive' Eclipse plugins (Help > Install new Software > Work with your Eclipse version site > Expand 'Collaboration' > Choose 'Subversive SVN JDT Ignore Extensions' and 'Subversive SVN Team Provider') but this didn't work for me (I'm on Indigo, perhaps on Juno it works).

The solution is to install the 21.1 preview version of the ADT tools and SDK manager from Google. Clear instructions can be found here and you can read all the background add your voice to the angry mob of developers here.

I just restarted Eclipse and the problem got solved.