While experimenting with gnome-3.8, I noticed that =gnome-extra/evolution-data-server-3.8.0 wouldn't compile with vala-0.18. I would hundreds of errors such as: EDataServer-1.2.gir:47.11-47.34: error: expected start element of `parameter' <instance-parameter name="closure" transfer-ownership="none"> ^^^^^^^^^^^^^^^^^^^^^^^^ Manually upgrading vala to 0.20 solved the problem.
*** This bug has been marked as a duplicate of bug 463720 ***