Main dispatcher missing on version 1.2.1 (android gradle plugin 3.5.0-beta02)

[sellmair]

When upgrading our project to coroutines version 1.2.1 (from 1.2.0), we get a

    java.lang.IllegalStateException: Module with the Main dispatcher is missing. Add dependency providing the Main dispatcher, e.g. 'kotlinx-coroutines-android'

Here are the relevant parts of our build.gradle:

---

root:

    ext.coroutines_version = '1.2.1'

---

one of many library modules in our project module:
(all looking basically the same, there is no import of another version somewhere)

dependencies {
    /* Test */
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

    /* Kotlin */
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"

    /* Coroutines */
    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutines_version"
    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutines_version"

---

Gradle version: 5.4.1
Android gradle plugin: 3.5.0-beta02

---

The same configuration works using the older agp version 3.4.0 or the older coroutines version 1.2.0

[sellmair]

Seems to work with agp version 3.5.0-beta01 as well.

[elizarov]

May I ask to report the bug to AGP then?

[LouisCAD]

I just reported it myself to bring awareness early to the Android Gradle plugin team: https://issuetracker.google.com/issues/133495912
@sellmair if you have additional details that could help them, please, share them into that linked issue.

[qwwdfsad]

Thanks, @LouisCAD!
I'll close this one then

[hungvietnguyen]

Could you provide a more detailed stacktrace to help us debug this issue, or even better, a sample project?

Please post it at https://issuetracker.google.com/issues/133495912.

[sellmair]

Sure, will do a sample project and post it 👍

[rabidaudio]

If anyone else stumbles across this, it seems to be that AGP 3.5.0 isn't including the META-INF/services/* files (similar to #983 ). There may be some proguard rules way to fix this but we just rolled back to AGP 3.4.0. I have a feeling more people are going to hit this now that 3.5.0 is recommended by Android Studio. I'm going to post this on the AGP issue as well.

[sgjesse]

@rabidaudio Are you seeing issues with coroutines and R8 after upgrading to AGP 3.5.0? Or are you just concerned that META-INF/services/kotlinx.coroutines.internal.MainDispatcherFactory is not present?

It is not necessarily an issue that META-INF/services/kotlinx.coroutines.internal.MainDispatcherFactory is not included. R8 can optimize/desugar the ServiceLoader calls when performing whole program optimization by rewriting the use of ServiceLoader to a direct instantiation of the class implementing the service. The coroutines library has code to ensure that this R8 optimization can kick in, and there is a test in the repo to test that the ServiceLoader class is not mentioned in the generated dex when using R8.

@wojtek-kalicinski and @JakeWharton have been working on getting the coroutines library and R8 to work seamlessly together, and they might have more precise information in which versions work well together.

(copied this to http://issuetracker.google.com/133495912 as well)

[wojtek-kalicinski]

FYI this doesn't seem to be related to any work I've been doing as my changes landed in AGP 3.6 canary 7 and coroutines 1.3.0.