Add an option to use @_implementationOnly import SwiftProtobuf

[wangjiejacques]

Currently the generated xxx.pb.swift always use import SwiftProtobuf, but sometimes we want to use @_implementationOnly import SwiftProtobuf, it would be nice to have an option to do so.

[teogeos]

For context: we make a library, an XCFramework used by our client's apps. Without @_implementationOnly we get a warning and lose ABI stability warranty.

[thomasvl]

If a proto file imports another one, it is likely because of the types (message/enums) are used as fields. So it wouldn't really be implementation only as the types are exposed by the types in the generate file.

I'm guessing you want the protos to be an implementation details of your types and you don't expose them? i.e. - they should be implementation imports of your code?

If that's what you are after, what's the error? Sounds like maybe this should be an issue agains Swift for the transitive imports of @_implementationOnly imports?

[teogeos]

We're not talking about protos importing other proto files. We're talking about importing the core SwiftProtobuf lib.

We're writing a framework that deals with protobufs. We call protoc to generate swift classes for our protos, then put the generated files in our project. But these generated files have import SwiftProtobuf, without @_implementationOnly, which means our framework loses ABI stability. As of now we have to add @_implementationOnly to the generated files ourselves.

We don't want to expose any type coming from SwiftProtobuf.

[wangjiejacques]

Following this discussion, @_implementationOnly import SwiftProtobuf probably should be the default behavior.

[thomasvl]

Ah, ok, I'm following now. I was mistakenly thinking you wanted all imports as impl only and that's what confused me.

[Lukasa]

@_implementationOnly should not be the default behaviour unless you like your code breaking in future Swift releases. 😉

[teogeos]

Makes sense to me not to make it default.

But do you think it could be a good idea to make it a code generation option?

[paynerc]

But do you think it could be a good idea to make it a code generation option?

It would be nice if there was an option for this... Ended up having a script do this after generating the .swift files.

[daniellfalcao]

@teogeos I'm trying to create a XCFramework with SwiftProtobuf dependency too but I got some erros describers here, can you give some tips? From what you said i think you obtained success to generate the framework

[Banck]

Hey!
Is there any way to generate swift files with @_implementationOnly attribute in protoc?

[Lukasa]

At this time there is not.

[tbkka]

The standard Unix sed command can replace text in groups of files.

[wangjiejacques]

Fixed by #1393