Undefined symbol when building for production with v2.0

[DavidI7]

Describe the bug

When I build the app for debugging, everything works fine. When I try to archive it, I get

Showing Recent Issues
Undefined symbol: protocol witness table for NIOHTTP2.NIOHTTP2AsyncSequence<A>.Continuation : NIOHTTP2.AnyContinuation in NIOHTTP2...

I downgraded grpc-swift to 1.24.2 and got something similar (I censored some classes&package names):

Undefined symbols for architecture arm64:
  "protocol witness table for GRPC.AsyncServerHandler<A, B, C, D> : GRPC.AsyncServerCallContextProvider in GRPC", referenced from:
      generic specialization <GRPC.ProtobufSerializer<demo....>, GRPC.ProtobufDeserializer<demo.....>, in ....grpc.o

However, when I changed the minimum iOS version required from 18.0 to 17.6, that error disappeared for v1.24.2. Obviously, I can't try and do this for v2.0 because GRPCCore's minimum deployment target is 18.0.

To reproduce

Steps to reproduce the bug you've found:

1. Add grpc-swift v.2.0.0, grpc-swift-nio-transport v1.0.0, grpc-swift-protobuf v.1.0.0
2. Try and archive the build.
3. The process fails with the errors above

Expected behaviour

You can build for production.

[glbrntt]

Hi @DavidI7 -- I couldn't reproduce this.

Here's what I did using Xcode 16.2:

• Created a new Xcode project for an iOS app
• Added grpc-swift v.2.0.0, grpc-swift-nio-transport v1.0.0, grpc-swift-protobuf v.1.0.0
• Imported the relevant modules in a view and used symbols from each
• Product > Archive

This worked fine.

Are there any settings you have which deviate from the defaults? And could you provide a minimal repro for this?

[DavidI7]

Hi ! First of all, thank you very much for your reply.

I attached 2 archives.

testy-test has a project with grpc-swift v2.0.
This is what I get when trying to archive this

 "protocol witness table for NIOHTTP2.NIOHTTP2AsyncSequence<A>.Continuation : NIOHTTP2.AnyContinuation in NIOHTTP2", referenced from:
      generic specialization <(NIOCore.NIOAsyncChannel<GRPCCore.RPCRequestPart<GRPCNIOTransportCore.GRPCNIOTransportBytes>, GRPCCore.RPCResponsePart<GRPCNIOTransportCore.GRPCNIOTransportBytes>>, NIOCore.EventLoopFuture<GRPCCore.MethodDescriptor>)> of (extension in NIOHTTP2):NIOCore.ChannelPipeline.SynchronousOperations.configureAsyncHTTP2Pipeline<A where A: Swift.Sendable>(mode: NIOHTTP2.NIOHTTP2Handler.ParserMode, streamDelegate: NIOHTTP2.NIOHTTP2StreamDelegate?, configuration: NIOHTTP2.NIOHTTP2Handler.Configuration, streamInitializer: @Sendable (NIOCore.Channel) -> NIOCore.EventLoopFuture<A>) throws -> NIOHTTP2.NIOHTTP2Handler.AsyncStreamMultiplexer<A> in GRPCNIOTransportCore.o
      generic specialization <()> of (extension in NIOHTTP2):NIOCore.ChannelPipeline.SynchronousOperations.configureAsyncHTTP2Pipeline<A where A: Swift.Sendable>(mode: NIOHTTP2.NIOHTTP2Handler.ParserMode, streamDelegate: NIOHTTP2.NIOHTTP2StreamDelegate?, configuration: NIOHTTP2.NIOHTTP2Handler.Configuration, streamInitializer: @Sendable (NIOCore.Channel) -> NIOCore.EventLoopFuture<A>) throws -> NIOHTTP2.NIOHTTP2Handler.AsyncStreamMultiplexer<A> in GRPCNIOTransportCore.o

And the second one, testy-test-1.24.2 uses grpc-swift v1.24.2 and the same files from the other project but generated manually by me using protoc. For this one, there's the initial problem that I've opened the issue with - it works if the target version is <18, or throws if the targeted iOS version is 18.0

      generic specialization <GRPC.ProtobufSerializer<testy_test.nameGrpc_Journal_CreateJournalEntryResponse>, GRPC.ProtobufDeserializer<testy_test.nameGrpc_Journal_CreateJournalEntryRequest>, testy_test.nameGrpc_Journal_CreateJournalEntryRequest, testy_test.nameGrpc_Journal_CreateJournalEntryResponse> of GRPC.AsyncServerHandler.receiveInterceptedMetadata(NIOHPACK.HPACKHeaders) -> () in journal.grpc.o
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I tried using both XCode 16.0 and 16.2.

testy-test-1.24.2.zip
testy-test.zip

[glbrntt]

Thanks for providing those, however, I can archive both of those with Xcode 16.2 (I didn't have a copy of Xcode 16.0 around to try out).

Have you tried deleting your derived data?

[DavidI7]

I managed to solve it, it was a combination of using only XCode 16.2, cleaning the build folder, deleting DerivedData and making sure to do all of this before using XCode 16.2 if coming from XCode 16.0.

I did only parts of this flow before and didn't get it to work, so I'm pretty sure it's something that got cached when I used XCode 16.0.

Thank you for your support, I think we can close the issue. If everyone ever encounters this error, make sure you have at least XCode 16.2 and a clean state of the project.