[SR-11906] Private methods of an open class are exposed to another framework extending this class #54323

swift-ci · 2019-12-05T11:03:18Z


Previous ID	SR-11906
Radar	rdar://problem/57712089
Original Reporter	wernera77 (JIRA User)
Type	Bug
Status	Closed
Resolution	Done

Attachment: Download

Environment

Xcode 11.2.1, Swift 5.1.2

Additional Detail from JIRA


Votes	2
Component/s	Compiler
Labels	Bug
Assignee	@aschwaighofer
Priority	Medium

md5: 53dfcb5053681526ac625a63f033a5a4

Issue Description:

We work with a lot of dynamic Swift frameworks and ran into the following scenario:

Framework1:

open class Ape {
    public init() {}

    public func foo() {
    }

    private func bar() {
    }
}

Framework2:

import Framework1

public final class Gorilla: Ape {
    public override init() {
        super.init()
        foo()
    }
}

Framework2 links to Framework1.

Now if we inspect the symbols present in Framework2 (by using `nm`) we find that the private func `bar()` is present.

This gives us big issues because we cannot rely on semantic versioning with prebuilt frameworks because of this (we use binary caches per swift version). To make this more clear:

Say we compile Framework2 with Framework1 version 1.1 which added some public methods and adds a private method (say `bar()`) in an open class.
However: Framework2 only requires version 1.0 of the Framework1 API and receives Framework1 version 1.0 at runtime.

=> A crash will occur at runtime because the added private method (which was introduced in 1.1) is not available.

beccadax · 2019-12-06T21:45:14Z

@swift-ci create

aschwaighofer · 2019-12-09T22:21:19Z

Did you use the Xcode build setting "build libraries for distribution" or alternatively did you use the command line flag -enable-library-evolution?

Otherwise, it is expected that you run into issues like the one you mention.

https://developer.apple.com/videos/play/wwdc2019/416/

swift-ci · 2019-12-10T10:52:24Z

Comment by Werner Altewischer (JIRA)

I just tried that, however even when building both frameworks with "BUILD_LIBRARY_FOR_DISTRIBUTION=YES" there are still private symbols present in the undefined symbols of Framework2.

e.g.

private symbol Framework1.x is listed in the output of `nm -u Framework2.framework/Framework2`

aschwaighofer · 2019-12-10T16:48:01Z

Something has gone wrong with the build settings then.

I have attached the example LibraryEvolution.zip.

If you open and build the UseSwiftFramework.xcodeproj project and list the symbols in UseSwiftFramework.framework there should not be a mention of the symbol bar.

swift-ci · 2019-12-11T11:30:51Z

Comment by Werner Altewischer (JIRA)

I see my mistake, I enabled the BUILD_LIBRARY_FOR_DISTRIBUTION only for Release mode. It does seem to work now, thanks.

swift-ci transferred this issue from apple/swift-issues Apr 25, 2022

This issue was closed.

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

[SR-11906] Private methods of an open class are exposed to another framework extending this class #54323

[SR-11906] Private methods of an open class are exposed to another framework extending this class #54323

swift-ci commented Dec 5, 2019

beccadax commented Dec 6, 2019

aschwaighofer commented Dec 9, 2019

swift-ci commented Dec 10, 2019

aschwaighofer commented Dec 10, 2019

swift-ci commented Dec 11, 2019

[SR-11906] Private methods of an open class are exposed to another framework extending this class #54323

[SR-11906] Private methods of an open class are exposed to another framework extending this class #54323

Comments

swift-ci commented Dec 5, 2019

beccadax commented Dec 6, 2019

aschwaighofer commented Dec 9, 2019

swift-ci commented Dec 10, 2019

aschwaighofer commented Dec 10, 2019

swift-ci commented Dec 11, 2019