Hopefully, this should do the job:

https://bitbucket.org/eigen/eigen/chang ... 623d65d52/
changeset: d73623d65d52
user: ggael
date: 2012-08-27 14:50:45
summary: workaround clang bug (see viewtopic.php?f=74&t=102653)

Hi ggael,
I just cloned the bitbucket repo, and this does seem to have fixed the problem. I'm now getting an Unused variable warning for 'PeelAlignedMask' in GeneralMatrixVector.h, but I would assume this is totally unrelated!
Thanks!

Can you be more specific. All the previous examples in this threads works fine now for me with clang 3.1.

Hi ggael,
XCode/Clang was reporting the unused "PeelAlignedMask" variable on line 84 in GeneralMatrixVector.h.

However, due to a different issue, I have recently switched the C++ dialect on my projects to C++11, linking to Apple's libc++ (which has C++11 support) rather than libstdc++. Clang has stopped reporting the unused variable issue, but now I'm getting a lot of "Implicit conversion loses integer precision" warnings in many Eigen headers. This seems to be because something (including .size()) suddenly become longs rather than ints.

Should I open a new topic about this?

yes, please. even better, report a bug entry in http://eigen.tuxfamily.org/bz with the above message and the list of warnings.

You may have already noticed but I added a note to bug 397 yesterday, as this described the same issue with Clang.