Add support for the CMAKE environmental variable

[marmistrz]

No description provided.

[alexcrichton]

Thanks for the PR! Is the precedent for doing somethign like this?

[marmistrz]

Yes, without this PR it's impossible to compile Servo on CentOS, since cmake is CMake 2.x, cmake3 is CMake 3.x. (more precisely, some of its deps, which uses target_sources)

[alexcrichton]

Could this perhaps automatically detect that and not require use of the env var? Do other projects use CMAKE?

[marmistrz]

I don't think it's a good idea. For example, in Arch you can install cmake 2.x to /usr/bin/cmake-2 and it may be useful to fall back to cmake 2 if there are some compatibility issues with cmake 3.

[alexcrichton]

Is the CMAKE env var standard in any other systems? I'd be somewhat wary of creating a "new standard" in a sense...

[marmistrz]

I have never seen anything like this, probably because cmake is usually run manually, where one can specify the path himself.
If you have an idea for a better variable, let me know.

[alexcrichton]

Ok sounds like we should go with this as is then, so I'll merge! Maybe we can now be trendsetters :)

[marmistrz]

The rusty avant-garde! :)
My plan for now:

1. Bump the version to include this change
2. Bump the cmake-rs dependency in gecko-media to allow build on CentOS
3. Edit the servo README with extra instructions how to build on CentOS.

Is it feasible? Should I just make a PR to this repo bumping the version to achieve 1.?

[alexcrichton]

Sounds reasonable! Nah it's ok I'll go ahead and do the bump