Support for XCFrameworks

[LakshmiChidambaranathan]

I am encountering a crash when creating an XCFramework for my SDK, which has SwiftProtobuf as a dependency via CocoaPods. By default, the BUILD_LIBRARIES_FOR_DISTRIBUTION setting is set to No when integrating through CocoaPods, but this needs to be overridden to Yes to properly use the XCFramework. Without this override, the crash occurs. It would be greatly beneficial if SwiftProtobuf could be provided as an XCFramework to avoid this issue.

Kindly find the other details as follows:

• Developing on Mac OS 14.6.1 (23G93) (Apple M1 Pro)

• for macOS, version of Xcode Version 15.4 (15F31d)

• Swift_version - 5.0

• tag of SwiftProtobuf - 1.26.0

• Crash - dyld[50182]: Symbol not found: _$s13SwiftProtobuf19_ProtoNameProvidingP17_protobuf_nameMapAA01_dH0VvgZTq
  Referenced from: //Library/Developer/CoreSimulator/Devices/6F58CF1E-7076-43C2-8CD3-75AA7BCA9827/data/Containers/Bundle/Application/6E33CC84-F7C0-4675-B04F-824EA2EB82E5/ProtobufBuildAnalysis.app/Frameworks/ZohoDeskPlatformUIKit.framework/ZohoDeskPlatformUIKit
  Expected in: <2B86F3DE-BBD4-3979-AEA5-8F626BC0BEB4> //Library/Developer/CoreSimulator/Devices/6F58CF1E-7076-43C2-8CD3-75AA7BCA9827/data/Containers/Bundle/Application/6E33CC84-F7C0-4675-B04F-824EA2EB82E5/ProtobufBuildAnalysis.app/Frameworks/SwiftProtobuf.framework/SwiftProtobuf

[Lukasa]

Thus far, the Swift Protobuf team have been reluctant to define a stable ABI for Protobuf (see #1101). For now we'd recommend that you use protobuf as a purely internal dependency of your framework (using internal import in Swift 6, or @_implementationOnly earlier). This will allow you to statically link it as you see fit.

[allevato]

In addition to using internal import or @_implementationOnly, you should also use -module-alias to rename SwiftProtobuf to something else when it's embedded in your framework. That way, if one of your clients is also using SwiftProtobuf, the symbols in their copy and your framework don't collide.

[LakshmiChidambaranathan]

@allevato , Could you kindly explain how to use -module-alias to rename SwiftProtobuf to something else when it's embedded in my framework. I actually have this case, where one of my client is also using SwiftProtobuf