Remote Config's addOnConfigUpdateListener crashing with Swift 6 set as Swift Language Version

[GoofSports]

Description

1. Firebase's Remote Config will crash when using with addOnConfigUpdateListener EXC_BREAKPOINT and corrupt remote config's data. This makes it impossible to use addOnConfigUpdateListener with swift 6.

Reproducing the issue

To reproduce the issue, download this sample remote config project. https://github.com/TharinduKetipe/RemoteConfigDemo/tree/develop

After downloading, run the app as is with Swift 5. The app will run correctly. Go into build settings and change Swift Language Version to Swift 6. Run the app again, and there is an immediate crash.

Firebase SDK Version

11.6.0

Xcode Version

16.1

Installation Method

Swift Package Manager

Firebase Product(s)

Remote Config

Targeted Platforms

iOS

Relevant Log Output

if (completion) {
   dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
      completion(NO, nil); // EXC_BREAKPOINT HERE
   });
}

If using Swift Package Manager, the project's Package.resolved

Expand Package.resolved snippet

{
  "pins" : [
    {
      "identity" : "abseil-cpp-binary",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/abseil-cpp-binary.git",
      "state" : {
        "revision" : "194a6706acbd25e4ef639bcaddea16e8758a3e27",
        "version" : "1.2024011602.0"
      }
    },
    {
      "identity" : "app-check",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/app-check.git",
      "state" : {
        "revision" : "21fe1af9be463a359aaf8d96789ef73fc3760d09",
        "version" : "11.0.1"
      }
    },
    {
      "identity" : "firebase-ios-sdk",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/firebase/firebase-ios-sdk.git",
      "state" : {
        "revision" : "1fc52ab0e172e7c5a961f975a76c2611f4f22852",
        "version" : "11.2.0"
      }
    },
    {
      "identity" : "googleappmeasurement",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/GoogleAppMeasurement.git",
      "state" : {
        "revision" : "07a2f57d147d2bf368a0d2dcb5579ff082d9e44f",
        "version" : "11.1.0"
      }
    },
    {
      "identity" : "googledatatransport",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/GoogleDataTransport.git",
      "state" : {
        "revision" : "617af071af9aa1d6a091d59a202910ac482128f9",
        "version" : "10.1.0"
      }
    },
    {
      "identity" : "googleutilities",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/GoogleUtilities.git",
      "state" : {
        "revision" : "53156c7ec267db846e6b64c9f4c4e31ba4cf75eb",
        "version" : "8.0.2"
      }
    },
    {
      "identity" : "grpc-binary",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/grpc-binary.git",
      "state" : {
        "revision" : "f56d8fc3162de9a498377c7b6cea43431f4f5083",
        "version" : "1.65.1"
      }
    },
    {
      "identity" : "gtm-session-fetcher",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/gtm-session-fetcher.git",
      "state" : {
        "revision" : "a2ab612cb980066ee56d90d60d8462992c07f24b",
        "version" : "3.5.0"
      }
    },
    {
      "identity" : "interop-ios-for-google-sdks",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/interop-ios-for-google-sdks.git",
      "state" : {
        "revision" : "2d12673670417654f08f5f90fdd62926dc3a2648",
        "version" : "100.0.0"
      }
    },
    {
      "identity" : "leveldb",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/firebase/leveldb.git",
      "state" : {
        "revision" : "a0bc79961d7be727d258d33d5a6b2f1023270ba1",
        "version" : "1.22.5"
      }
    },
    {
      "identity" : "nanopb",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/firebase/nanopb.git",
      "state" : {
        "revision" : "b7e1104502eca3a213b46303391ca4d3bc8ddec1",
        "version" : "2.30910.0"
      }
    },
    {
      "identity" : "promises",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/google/promises.git",
      "state" : {
        "revision" : "540318ecedd63d883069ae7f1ed811a2df00b6ac",
        "version" : "2.4.0"
      }
    },
    {
      "identity" : "swift-protobuf",
      "kind" : "remoteSourceControl",
      "location" : "https://github.com/apple/swift-protobuf.git",
      "state" : {
        "revision" : "edb6ed4919f7756157fe02f2552b7e3850a538e5",
        "version" : "1.28.1"
      }
    }
  ],
  "version" : 2
}

If using CocoaPods, the project's Podfile.lock

Expand Podfile.lock snippet

Replace this line with the contents of your Podfile.lock!

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[ErikLuimes]

We have the same issue

[paulb777]

The repo doesn't build for me on Xcode 16.2

If I add @preconcurrency to RemoteConfigProvider, the app starts up without crashing

[ErikLuimes]

Below is a stacktrace, I can't reproduce it in the simulator or on my own device but we see some of these crashes in our Beta group. It happens when the remote update closure is called

remoteConfig.addOnConfigUpdateListener { config, error in
        
}

Crashed: com.google.GoogleConfigService.FIRRemoteConfig
0  libdispatch.dylib              0x64d8 _dispatch_assert_queue_fail + 120
1  libdispatch.dylib              0x6460 _dispatch_assert_queue_fail + 194
2  libswift_Concurrency.dylib     0x62b78 swift_task_isCurrentExecutorImpl(swift::SerialExecutorRef) + 284
3  APP                           0x259170 closure #2 in static AppSetup.setupRemoteConfig() + 4376236400 (<stdin>:4376236400)
4  APP                           0x259cd8 thunk for @escaping @callee_guaranteed (@guaranteed FIRRemoteConfigUpdate?, @guaranteed Error?) -> () + 4376239320 (<compiler-generated>:4376239320)
5  APP                           0xa1ff14 __37-[RCNConfigRealtime propogateErrors:]_block_invoke + 161 (RCNConfigRealtime.m:161)
6  libdispatch.dylib              0x2370 _dispatch_call_block_and_release + 32
7  libdispatch.dylib              0x40d0 _dispatch_client_callout + 20
8  libdispatch.dylib              0xb6d8 _dispatch_lane_serial_drain + 744
9  libdispatch.dylib              0xc1e0 _dispatch_lane_invoke + 380
10 libdispatch.dylib              0x17258 _dispatch_root_queue_drain_deferred_wlh + 288
11 libdispatch.dylib              0x16aa4 _dispatch_workloop_worker_thread + 540
12 libsystem_pthread.dylib        0x4c7c _pthread_wqthread + 288
13 libsystem_pthread.dylib        0x1488 start_wqthread + 8

[paulb777]

@ErikLuimes That crash may have been addressed in the 11.5.0 release. See #13776 and #13825