Type conformance error while implementing ClientInterceptor

[jeevansurendran]

Describe the bug

I am trying to create a custom interceptor that propogates few extra header information. I implemented the code as per the example. But i keep getting the error:

My code implementation is somewhere around this:

import GRPCCore

struct AuthInterceptor: ClientInterceptor {
    
    func intercept<Input: Sendable, Output: Sendable>(r
        request: StreamingClientRequest<Input>,
        context: ClientContext,
        next: @Sendable (
            _ request: StreamingClientRequest<Input>,
            _ context: ClientContext
        ) async throws -> StreamingClientResponse<Output>
    ) async throws -> StreamingClientResponse<Output> {
        var request = request
        request.metadata.replaceOrAddString("stoelkf", forKey: "authorization")
        return try await next(request, context)
    }
}

the grpc project version i am using is: 2.1.0, but i also tried with the latest commit in this repo but it didnt help

To reproduce

My Xcode version is 26.0.1 (17A400).
swift-driver version: 1.127.14.1 Apple Swift version 6.2 (swiftlang-6.2.0.19.9 clang-1700.3.19.1)
Target: arm64-apple-macosx26.0

Steps to reproduce the bug you've found:

1. Create a new iOS project
2. Import grpc-swift-2
3. Add the code

import GRPCCore

struct LoggingClientInterceptor: ClientInterceptor {
    
    func intercept<Input: Sendable, Output: Sendable>(r
        request: StreamingClientRequest<Input>,
        context: ClientContext,
        next: @Sendable (
            _ request: StreamingClientRequest<Input>,
            _ context: ClientContext
        ) async throws -> StreamingClientResponse<Output>
    ) async throws -> StreamingClientResponse<Output> {
        print("Invoking method '\(context.descriptor)'")
        let response = try await next(request, context)
        
        switch response.accepted {
        case .success:
            print("Server accepted RPC for processing")
        case .failure(let error):
            print("Server rejected RPC with error '\(error)'")
        }
        
        return response
    }
}

you should get the error:

Expected behaviour

1. ideally i should have no trouble implementing the protocol and compiler should not throw any error

Additional information

I am new to swift, but i am well versed with grpc. I might be missing something obvious too.

[glbrntt]

Hi, I added a couple of comments to your code where the issues are:

import GRPCCore

struct AuthInterceptor: ClientInterceptor {
    
    func intercept<Input: Sendable, Output: Sendable>(r // <--- There's an extra 'r' here
        request: StreamingClientRequest<Input>,
        context: ClientContext,
        next: @Sendable ( // <--- You need to remove the @Sendable
            _ request: StreamingClientRequest<Input>,
            _ context: ClientContext
        ) async throws -> StreamingClientResponse<Output>
    ) async throws -> StreamingClientResponse<Output> {
        var request = request
        request.metadata.replaceOrAddString("stoelkf", forKey: "authorization")
        return try await next(request, context)
    }
}

[jeevansurendran]

@glbrntt this must have been a copying mistake while i was making the github issue, you can see it still fails here.

[glbrntt]

That code compiles for me just fine. Did you try a clean build?

[jeevansurendran]

Yes, I first tried cleaning the build folder in my project. Then later I created a new project and tried just creating a single Interceptor file in the project and still got the same error. Later I tried getting onto on the latest xcode beta version and had the same issue. I also did try restarting my PC :(

This is what i did to clean the build.

1. Product → Clean Build Folder.
2. Xcode→ Settings → Locations → Derived Data and delete the folder.
3. File → Packages → Reset Package Caches
4. File → Packages → Resolve Package Versions

[jeevansurendran]

@glbrntt were you able to reproduce this?

[glbrntt]

No. Do you think you could attach an xcodeproj which reproduces this?

[jeevansurendran]

Hi, I have attached the ZIP file.

test.zip

[jeevansurendran]

Version 26.1 (17B55)