[cfe-dev] Raising CMake minimum version to 3.4.3

Tue Apr 26 15:50:14 PDT 2016

> On Apr 26, 2016, at 3:47 PM, John Criswell <jtcriswel at gmail.com> wrote:
> 
> On 4/26/16 6:01 PM, Chris Bieneman via cfe-dev wrote:
>> Hello llvm-dev and cfe-dev,
>> 
>> I want open up the discussion of upgrading our minimum required CMake version.
>> 
>> In the past when we’ve discussed this one of the major reasons for not moving forward was that the Ubuntu LTS release was on CMake 2.8.12.x. A few days ago Ubuntu 16.04, the new LTS, was released, and it contains CMake 3.5.1.
>> 
>> I have a couple of motivations for this, the biggest of which is that I’ve hit a wall trying to overcome some limitations in the CMake ExternalProject module which I can’t get past without being on CMake 3.4 or newer. These limitations make using ExternalProject to build the LLVM test-suite and runtime libraries (compiler-rt, libcxx, etc) difficult.
>> 
>> The other big motivation that I have for this is the ability to cleanup code. We have a lot of CMake code that checks CMAKE_VERSION and enables and disables features used on the version. None of the places where we currently have CMAKE_VERSION checks should impact build correctness, but most people don’t realize that if you’re using Ninja your build will be faster on a newer CMake than on an older one. It would be nice if we just pushed the bar up and could remove a bunch of those conditionals.
>> 
>> To do this we need bot maintainers to update their CMake installations, so we need some consensus that (1) we want to do this and (2) what a reasonable timeline for doing it is.
>> 
>> What I’d like to do is raise the minimum version for all LLVM projects to CMake 3.4.3 at the end of May. Setting the date at the end of May gives bot maintainers and developers lots of time to update, and CMake 3.4.3 is the last CMake 3.4 release and it is widely available. For reference here’s a list of linux distributions and their CMake versions:
>> 
>> Ubuntu Wily -> 3.2.2
>> Ubuntu Xenial -> 3.5.1
>> Ubuntu Yakkety -> 3.5.1
>> Debian jessie -> 3.0.2
>> Debian stretch -> 3.5.1
>> Debian sid -> 3.5.2
>> FreeBSD 10.2 -> 3.5.0
>> FreeBSD HEAD -> 3.5.2
>> 
>> Feedback?
> 
> How did you determine that FreeBSD 10.2 is using cmake 3.5.0?  On my FreeBSD 10.3 system, I have cmake version 3.4.1 (I think it got installed from ports when I installed other software).

I have a fully updated FreeBSD 10.2 machine and ran “pkg search cmake”. It came back with 3.5.0. I’m not sure what version it released with, but the updated version is in the ports collection.

> 
> Also, I see that you sent this to llvm-dev at lists.apple.com <mailto:llvm-dev at lists.apple.com>. Shouldn't this also go to llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org> (or are they the same list)?

I auto-completed llvm-dev incorrectly on my original email and have been fixing it on subsequent replies.

> 
> Third, just to nitpick, FreeBSD is not a Linux distribution.  :)

Should have probably said *nix :-)

-Chris

> 
> Regards,
> 
> John Criswell
> 
>> 
>> Thanks,
>> -Chris
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>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev <http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev>
> 
> 
> -- 
> John Criswell
> Assistant Professor
> Department of Computer Science, University of Rochester
> http://www.cs.rochester.edu/u/criswell <http://www.cs.rochester.edu/u/criswell>
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