Hello fellow developers,
Now that CMake 3.15 has been out for a while and 3.15.2 is the current release, I would like to propose moving the minimum version for building Swift to jump to 3.15.
I realize that bumping tools is challenging. We have three build hosts to currently consider:
In the case of macOS, the build instructions recommend installing CMake via brew, which has 3.15.2 as the current release (https://formulae.brew.sh/formula/cmake). Although Visual Studio distributes 3.14 still, installation of 3.15 is easy as there is an installer available for Windows. This leaves Linux. Thanks to @spevans, on Linux, we now build CMake if it is not new enough.
This means that CMake is easily available on all the platforms with a new enough version. This means that we can get proper build support for Swift targets, which is extremely helpful in simplifying the build rules for Dispatch, Foundation, and will enable easily bootstrapping swift-package-manager on Windows. Additionally, it also brings along a large number of improvements which will allow us to simplify the current build.
I would like to make this change soon so that we can start cleaning up some of the complexity in the build system.