[RFC] Raise minimum required CMake version to

Hello LLVM-Dev!

I would like to request that we raise the minimum required CMake version to

My primary reason is that I would like to re-land this patch http://reviews.llvm.org/D8380 which broke the buildbots due to using a CMake 2.8.12 feature (see: http://lab.llvm.org:8011/builders/polly-amd64-linux/builds/28499/steps/cmake-configure/logs/stdio)

Additionally since we are updating MSVC users would benefit from a fix in, and Xcode users would benefit from fixes in

CMake is also the version in Ubuntu Trusty.


I also meant to include this URL to the change log for CMake 2.8.12.x:



Thanks for temporarily reverting and sorry for the breakage.

I already had cmake 3.* installed on my buildbot, but the cached configure script was still referring to the old cmake version. I fixed this now, such that this commit should not break anymore on my bot.

(I personally am not negatively affected by this update so no complains


Since we’ve hashed this issue to death, and we had previous agreement to make this change (see: http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-February/081966.html) I’m going to commit this change later this afternoon.

Please speak up now if you have any problems with this.