Add a dynamic and static library product of SwiftSyntax to Package.swift

[ahoppen]

Address #25 (comment).

We should not specify the type of the library product via an environment variable. Instead a cleaner approach is to have both a static and a dynamic library product in the package and just build the type of the library that is needed.

[ahoppen]

@swift-ci Please test

[ahoppen]

CC @nkcsgexi

[nkcsgexi]

Thanks, @ahoppen ! I was just about to do this myself. Your comment makes total sense.

[nkcsgexi]

Wait, i get this error when building locally:

Linking ./.build/x86_64-apple-macosx10.10/debug/libSwiftSyntax-dynamic.dylib
Compile Swift Module 'lit_test_helper' (3 sources)
<unknown>:0: error: module name "SwiftSyntax-dynamic" is not a valid identifier

We don't wanna change either the dylib name or the module name. Any idea how to resolve?

[ahoppen]

@nkcsgexi How did you get this error? I cannot reproduce it on my machine.

Renaming the product name to something that doesn't include a dash should probably resolve the issue, although I don't quite understand what the issue is.

[nkcsgexi]

I can see the error either by invoking Swift-side build script:

swift/utils/build-script --swiftsyntax --skip-test-cmark --skip-test-swift --skip-test-llbuild --skip-test-swiftpm --no-assert --skip-build-benchmarks --verbose -t

or invoking the swift-syntax build script alone:

$./swift-syntax/build-script.py

I'll revert this change for now till we have a good solution for preserving dylib names; plus linking SwiftSyntax statically makes sense to be the default setting for our users for now.

[ahoppen]

I was able to reproduce the issue if using swift-build that is bundled with Xcode 10.1 (10B61) but not with SwiftPM built from master. I haven't looked into if this is an issue in SwiftPM that has been fixed but is one of the reasons why I preferred to use a ToT SwiftPM to build SwiftSyntax and not a version of SwiftPM that happens to be installed on the system.

[nkcsgexi]

yeah, unfortunately using the SwiftPM from the environment is almost a hard requirement for us to submit. We can put a ping on this and wait till SwiftPM from the environment is up to date and then change the Package.swift file to the right configuration.

[ahoppen]

Ah, OK. Well. In that case it looks like we can only make this change once the next version of SwiftPM has shipped.