feat: Enables strict concurrency

Author: NeedleInAJayStack

Package.swift

@@ -27,5 +27,6 @@ let package = Package(
             name: "GraphQLWSTests",
             dependencies: ["GraphQLWS"]
         ),
-    ]
+    ],
+    swiftLanguageVersions: [.v5, .version("6")]
 )

Sources/GraphQLWS/GraphQLWSError.swift

@@ -88,7 +88,7 @@ struct GraphQLWSError: Error {
 }
 
 /// Error codes for miscellaneous issues
-public enum ErrorCode: Int, CustomStringConvertible {
+public enum ErrorCode: Int, CustomStringConvertible, Sendable {
     // Miscellaneous
     case miscellaneous = 4400
 

Sources/GraphQLWS/Server.swift

@@ -4,7 +4,7 @@ import GraphQL
 /// Server implements the server-side portion of the protocol, allowing a few callbacks for customization.
 ///
 /// By default, there are no authorization checks
-public class Server<InitPayload: Equatable & Codable> {
+public class Server<InitPayload: Equatable & Codable>: @unchecked Sendable {
     // We keep this weak because we strongly inject this object into the messenger callback
     weak var messenger: Messenger?
 

Tests/GraphQLWSTests/Utils/TestAPI.swift

@@ -16,7 +16,7 @@ struct TestAPI: API {
     }
 }
 
-final class TestContext {
+final class TestContext: Sendable {
     let publisher = SimplePubSub<String>()
 
     func hello() -> String {
@@ -35,7 +35,7 @@ struct TestResolver {
 }
 
 /// A very simple publish/subscriber used for testing
-class SimplePubSub<T> {
+class SimplePubSub<T: Sendable>: @unchecked Sendable {
     private var subscribers: [Subscriber<T>]
 
     init() {

Tests/GraphQLWSTests/Utils/TestMessenger.swift

@@ -7,14 +7,14 @@ import Foundation
 ///
 /// Note that this only retains a weak reference to 'other', so the client should retain references
 /// or risk them being deinitialized early
-class TestMessenger: Messenger {
+class TestMessenger: Messenger, @unchecked Sendable {
     weak var other: TestMessenger?
     var onReceive: (String) async throws -> Void = { _ in }
     let queue: DispatchQueue = .init(label: "Test messenger")
 
     init() {}
 
-    func send<S>(_ message: S) async throws where S: Collection, S.Element == Character {
+    func send<S: Sendable>(_ message: S) async throws where S: Collection, S.Element == Character {
         guard let other = other else {
             return
         }