[SR-6969] Support apinotes for revising C APIs

[Lukasa]

Previous ID	SR-6969
Radar	rdar://problem/37391693
Original Reporter	@Lukasa
Type	New Feature
Status	Resolved
Resolution	Done

Attachment: Download

Additional Detail from JIRA

Votes	0
Component/s	Package Manager
Labels	New Feature
Assignee	None
Priority	Medium

md5: 72f523b6a8075ff7c85272f077074b1f

Issue Description:

Occasionally when wrapping third-party C APIs it would be convenient to convince Swift to hide or differently expose the types in the underlying library. The Swift standard library does this by using apinotes, and while it is possible to create your own these are system-specific and SwiftPM does not provide any tools for distributing them.

It would be extremely convenient if SwiftPM came up with a way to support this use-case in a productised way.

[ddunbar]

@swift-ci create

[aciidgh]

What does Swift compiler expect here? If its only -I, this should already work if you place the apinote file in include/ directory of a C target. /cc @belkadan

[belkadan]

The API notes go next to the module map defining the module for a non-framework target. That seems perfectly compatible with C targets today, but I don't know if we actually have it all set up to work.

[aciidgh]

Thanks Jordan. I tested this and it already works. Attached a sample package to this JIRA.

[ddunbar]

Awesome, thanks @aciidb0mb3r @belkadan

[swift-ci]

Comment by Ryan Lovelett (JIRA)

I'm not sure this is 100% working. At least not with Swift 4.2.

If you use the attached potato.zip project and do swift package generate-xcodeproj --enable-code-coverage the resulting project cannot be compiled in Xcode.

You get a error/fixit saying:

Use of unresolved identifier 'howManyPotatoes'; did you mean 'how_many_potatoes'?

Beyond that I still don't know how this would work when using a System Library target.

[rauhul]

This does not work using the sample attached when using:

swift-driver version: 1.59 Apple Swift version 5.7 (swiftlang-5.7.0.118.4 clang-1400.0.27)
Target: arm64-apple-macosx13.0