`@inlinable` attributes on `_TinyArray` cause errors in `xcodebuild`

[xcodedave]

Hi,

I'm experiencing issues with version 1.10.0 when attempting to archive a distributable static library including swift-certificates as a dependency.

the _TinyArray type defines a few @inlinable nested types.

No explicit init function for _TinyArray is provided, and instead the synthesized internal init is used throughout various specialized initializers.

Unfortunately, this causes errors when building as an xcode archive for distribution, such as the following:

_TinyArray.swift:78:22: error: 'self' used before 'self.init' call or assignment to 'self'
        self.storage = .init(elements)
                     ^

I have created a simple demonstration of the issue here:
https://github.com/xcodedave/swift-certificates-issue

It includes a potential fix which is to provide an explicit init marked with the @usableFromInline attribute, and update property setting within specialized initializers to adopt the new explicit initializer.

[Lukasa]

Thanks for filing this! I suspect this only affects attempts to build with BUILD_LIBRARY_FOR_DISTRIBUTION enabled, which is not formally a configuration we support and is why this issue slipped through.

We’d welcome a PR that fixes this for you.

[rnro]

I was able to create a minimal reproducer of this issue and I believe it is indeed linked to BUILD_LIBRARY_FOR_DISTRIBUTION. Unfortunately when I took a quick Look at working around it for _TinyArray it just revealed more issues so it might be a bigger fix than it immediately appears.

[xcodedave]

Thanks for filing this! I suspect this only affects attempts to build with BUILD_LIBRARY_FOR_DISTRIBUTION enabled

@Lukasa that's exactly right - it happens due to the module visibility of _CertificateInternals I think

We’d welcome a PR that fixes this for you.

I'd love to contribute! Unfortunately, I've had a look at fixing this myself via PR - however, the issue is cascading. In some other Apple dependencies of swift-certificates the same initializer inlining pattern (and errors) appear. I guess I'd need a sequence of PRs working backwards up the dependency tree!

I think this might be a bug in the swift compiler, specifically around initializer synthesis when a type's properties are marked @inlinable. To this effect, I've also filed a Feedback Assistant report to the xcode-team with id FB17664788.

@Lukasa if I work out the order of PR's and repos, I can map them out here, and I'd be happy to take a go at this on the weekend 👍

[Lukasa]

👍 Sounds like a great plan, we're more than happy to take the tweaks throughout the stack.

[SofiaLopesNEC]

Any updates on this?

[Lukasa]

Nope: nobody has come forward to make this change.