[PROJ] Bump CMake version for PROJ 7.0

[Pierre Abbat]

On Monday, 13 January 2020 15.49.31 EST Mike Taves wrote:
> Hi all,
> 
> As was suggested in https://github.com/OSGeo/PROJ/pull/1542 this is a
> discussion to bump the minimum CMake version for PROJ 7.0
> 
> Based on the default versions of CMake [1], I can see that CMake 3.9
> is installed on most development systems, including Travis CI, so this
> would be an ideal minimum.
> 
> CMake 3.9.0 was released [2] July 2017, so is at least 2 years old for
> PROJ RFC 3's requirement.
> 
> One feature from this version that I plan to implement is
> CheckIPOSupported [3] module. GoogleTest [4] was added for this
> release, however I don't think it would provide any advantage.
> 
> Any other thoughts or suggestions on other CMake versions?

I set the minimum to 3.8 for PerfectTIN because it requires C++17 because it 
uses readers-writer locks. The rest of my projects have a minimum of 3.1 if 
they use Qt and 2.8 otherwise, except for a few oddballs.

Two years old sounds good. That's how often Ubuntu releases LTS versions. But 
you may run into people who still run RHEL 7. A few weeks ago I got PerfectTIN 
to run on a CentOS 7 box, where the compiler understood C++17 but CMake did 
not. It took much manularity.

Pierre

-- 
gau do li'i co'e kei do