[master] Move SwiftSyntax to its own repository

[ahoppen]

This PR sets up the infrastructure to build SwiftSyntax from its own repository. For this it does:

• Add the new swift-syntax repository to update-checkout
• Add a build-script option to build and test swift-syntax
• Update the build presets to test SwiftSyntax when running @swift-ci Please test
• Remove SwiftSyntax from this repository

[ahoppen]

@swift-ci Please test

[harlanhaskins]

LGTM, pending passing on CI.

This shouldn’t break folks who haven’t cloned swift-syntax, right? They just won’t pass —build-swiftsyntax

[ahoppen]

The flag to pass to build-script is --swiftsyntax but yeah, that should be the case. I'll double check locally.

Update: Confirmed that everything works if swift-syntax is not checked out and --swiftsyntax is not passed to build-script.

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 66a56b386f737adf50b73fc9c5b9f2394ec966e8

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 66a56b386f737adf50b73fc9c5b9f2394ec966e8

[ahoppen]

@swift-ci Please test

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 66a56b386f737adf50b73fc9c5b9f2394ec966e8

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 66a56b386f737adf50b73fc9c5b9f2394ec966e8

[slavapestov]

What's the rationale for moving it out? Are we still going to build it in CI?

[ahoppen]

We are still going to build it as part of CI if you do @swift-ci Please test.

There are multiple reasons to move this out:

• If it is a SwiftPM project, people can depend on it while still using the default Xcode toolchain which doesn't include SwiftSyntax.
• SwiftSyntax can now depend on corelibs-foundation which will make it a lot easier to port to Linux. Otherwise the compiler project would have needed to depend on Foundation which was not desirable.
• The package should be more discoverable and have a lower burden to contribute to this way.
• If the development is a little bit more separate from the compiler we should be able to accept minor improvements to the Swift side more easily that would otherwise be blocked by a locked down release branch.

[ahoppen]

Fixed the issue that caused this in the swift-syntax repo.

@swift-ci Please test

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 16724eee9efe58340bc7bdcdc67c81184291deee

[shahmishal]

@swift-ci build toolchain

[shahmishal]

@swift-ci Please Build Toolchain

[swift-ci]

Linux Toolchain (Ubuntu 16.04)
Download Toolchain
Git Sha - 16724eee9efe58340bc7bdcdc67c81184291deee

Install command
tar zxf swift-PR-19061-48-ubuntu16.04.tar.gz
More info

[ahoppen]

@swift-ci Please test

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 16724eee9efe58340bc7bdcdc67c81184291deee

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 16724eee9efe58340bc7bdcdc67c81184291deee

[swift-ci]

macOS Toolchain
Download Toolchain
Git Sha - 16724eee9efe58340bc7bdcdc67c81184291deee

Install command
tar -zxf swift-PR-19061-62-osx.tar.gz --directory ~/