Update to be compatible with swift-syntax 602.0.0

[scottrhoyt]

Issue/Motivation

This allows MapLibreSwiftUI to build against swift-syntax 602.0.0. Since the release of swift 6.2, the experimental prebuilts functionality was removed for 6.1. This restores the ability to use swift-syntax prebuilts to dramatically speed up build times.

[hactar]

Changes look sane, but the tests are failing?

[scottrhoyt]

I updated to swift-syntax 602.0.0 explicitly in the Package.resolved let's see if that's it. It's the same issue that @ianthetechie was mentioning on the Discord.

[scottrhoyt]

Still failing, do you happen to know what version of Xcode and swift the test runner is using?

[ianthetechie]

It was Slack but same difference ;)

The Xcode version is 26.0.0. You can find this buried in the build logs.

[scottrhoyt]

I was building the MapLibreSwiftUI library and not the MapLibreSwiftUI-Package scheme synthesized by SPM. Once I switched, I reproed the build error.

The package scheme builds the test targets as well which reveals the error. The tests depend on https://github.com/pointfreeco/swift-macro-testing which in turn extends swift-syntax. This sort of mixing of build environments is Xcode is a known issue currently.

The immediate solution is to disable prebuilts for the GitHub build using...

defaults write com.apple.dt.Xcode IDEPackageEnablePrebuilts NO

...which I verified to work locally in building the *-Package scheme. Downstream deps can still use the prebuilts as they aren't building the test code.

Note: If you are testing this locally, you will need to reset your package cache and clean your project to fully flush the pre-built and build swift-syntax from source.

So this change should be fine in that it doesn't introduce any problems that don't already exist. A separate change to disable prebuilts for the GH actions is recommended.

[scottrhoyt]

Rebased on the CI changes, so this should be good to go now.