Make EventLoopFuture.hopTo(eventLoop:) public again.

[MrMage]

This was accidentally made internal with #947.

Maybe there should be a separate test case file (with a non-@testable import) that verifies that all public interfaces are still present?

[MrMage]

@swift-nio-bot test this please

[normanmaurer]

ouch... LGTM. Thanks!

[normanmaurer]

Verify API / ABI breakage would be good for sure... I wonder if there is anything similar to what we have in java to verify this sort of stuff in netty:

https://siom79.github.io/japicmp/MavenPlugin.html

Basically it always confirms the current "branch" to the last stable release and fails the build if there is an API / ABI issue.

[Lukasa]

Verifying ABI breakage is not relevant due to the lack of stable ABI on Linux, so we don't need to worry about that.

Verifying API breakage in Swift is an unsolved problem. We'd have to invest time in writing tooling that presumably uses SwiftSyntax or something similar to generate an idea of what the public interface to SwiftNIO even is, and then to write diffing tools that understand the semantic nature of the changes. This is a hard problem.

Writing tests that don't use @testable imports is always better: we should consider whether we can split these future tests up to avoid doing so.

[MrMage]

Verifying API breakage in Swift is an unsolved problem. We'd have to invest time in writing tooling that presumably uses SwiftSyntax or something similar to generate an idea of what the public interface to SwiftNIO even is, and then to write diffing tools that understand the semantic nature of the changes. This is a hard problem.

I think Xcode sometimes gets confused when Cmd-clicking a library symbol and only shows that library's exports, rather than the implementation source file. Maybe that could be a place to start. I could imagine that it would be easier to simply wait until that tooling has improved though, rather than invest unreasonable amounts of time now.

[weissi]

Ouch! I think the Swift team somewhere have a public API diffing tool. We need that kind of thing.