Latest Xcode image (10.2) has drawbacks with the image OS (10.14.3)

It took quite a sequence of topics to understand this issue. To boil it down, Swift 5 binaries built with Xcode 10.2 require the Swift 5 Runtime Support for Command Line Tools, which are not included in macOS < 10.14.4 (must be directly downloaded from More Downloads in Apple Developer). As of 11 days ago, this controversial topic has made its mark on Homebrew, which now requires that formulae that depend on Xcode to either a) xcode-select <=10.1, or b) update the host system to 10.14.4+.

We use Homebrew to install a number of dependencies, including SwiftLint and Carthage. Both of these formulae depend on Xcode. When we update to use the 10.2 image, we get this error:

Xcode >=10.2 requires macOS >=10.14.4 to build many formulae.

As of 10.14.4, the Swift 5 Runtime Support CLT are shipped as part of macOS. These problems would all go away if the associated CircleCI image is updated.

Relevant Swift topic:
Homebrew discussion:


I just ran into this problem as well. Is there an ETA for them to update to 10.14.4?

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Looks like this has also been raised on this thread:

Keeping discussion to one thread: Xcode 10.2 image released