App crash on creating ViewModel only when minifyEnabled and with LifeCycle v 2.1.0

Question

My app is crashing on launch with a LinkageError when creating a view model using lazy{}. The crash only happens when:

1. minifyEnabled is set to true in build.gradle, AND
2. I use ver. 2.1.0 of lifecycle components. It works fine with lifecycle-2.0.0 with minifyEnabled

    def lifecycle_version = '2.1.0'
    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version"
    implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version"

Also, the crash is only happening for one of the view models. Other view models in the same activity that are touched before this one, aren't crashing the app.

---

The crash happens on the second line here:

    private val searchStackViewModel by lazy {
        ViewModelProviders.of(this)[SearchStateViewModel::class.java]
    }

The SearchStateViewModel is:

class SearchStateViewModel : ViewModel() {

    // Live data that initialises to empty stack with SearchStack.init
    private val privateStack = MutableLiveData<SearchStack>().apply {
        value = SearchStack()
    }

    // Observable view of search stack so it can't be directly modified
    internal val stateStack : LiveData<SearchStack> = privateStack

    /**
     * Add state to stack
     */
    fun add(searchState: SearchState) {
        val current = privateStack.value ?: SearchStack()
        current.add(searchState)
        privateStack.value = current
    }

    /**
     * Clear stack
     */
    fun clear() {
        val current = privateStack.value ?: SearchStack()
        current.clear()
        privateStack.value = current
    }

    /**
     * Clear stack, then add current state as the only state
     */
    fun clearThenAdd(searchState: SearchState) {
        val current = privateStack.value ?: SearchStack()
        current.clear()
        current.add(searchState)
        privateStack.value = current
    }

    /**
     * Get currentState search state, without changing the stack
     */
    fun currentState(): SearchState {
        return privateStack.value?.last() ?: SearchState()
    }

    /**
     * Return currentState search state, and remove it from the stack
     */
    fun pop(): SearchState {
        val current = privateStack.value ?: SearchStack()
        val poppedState = current.pop()
        privateStack.value = current
        return poppedState
    }
}

SearchStack is just an ArrayList:

class SearchStack : ArrayList<SearchState>() {

    init {
        add(SearchState())
    }


    fun pop(): SearchState = if (lastIndex > 0) removeAt(lastIndex) else last()


    override fun clear() {
        super.clear()
        add(SearchState())
    }


    override fun add(element: SearchState): Boolean {
        if (element == lastOrNull())
            return false
        return super.add(element)
    }
}

And SearchState is a data class:

@Parcelize
data class SearchState(
        val searchTerm: String = "",
        val isComplete: Boolean? = null,
        val dueOnly: Boolean = false,
        val aliveOnly: Boolean = true,
        val priority: Char? = null,
        val project: String? = null,
        val priorityMatchType: PriorityMatchType? = null,
        val name: String = "",
        val hideThresholdTasks: Boolean = true,
        val sortOrder: Int = -1,
        val sortOrderString: String? = null
                      ) : Parcelable {

    enum class PriorityMatchType {
        GREATOR,
        LESSOR,
        EXACT
    }

    enum class TaskState {
        DUE,
        PENDING,
        COMPLETED,
        ALL
    }

---

Stacktrace:

FATAL EXCEPTION: main
    Process: net.c306.ttsuper, PID: 7380
    java.lang.LinkageError: i.a.a.o.b
1 >>    at net.c306.ttsuper.view.ui.MainActivity$v.b(SourceFile:182)
        at net.c306.ttsuper.view.ui.MainActivity$v.b(SourceFile:159)
        at g.j.a(SourceFile:74)
        at net.c306.ttsuper.view.ui.MainActivity.F(SourceFile)
2 >>    at net.c306.ttsuper.view.ui.MainActivity.c(SourceFile:1839)
        at net.c306.ttsuper.view.ui.MainActivity.a(SourceFile:1993)
        at net.c306.ttsuper.view.ui.MainActivity.a(SourceFile:1967)
        at net.c306.ttsuper.view.ui.MainActivity.onCreate(SourceFile:386)
        at android.app.Activity.performCreate(Activity.java:6251)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
        at android.app.ActivityThread.-wrap11(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:148)
        at android.app.ActivityThread.main(ActivityThread.java:5417)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Line labeled (1) is the lazy create of ViewModel where the crash happens.
Line labeled (2) is the first access of ViewModel that initiates the lazy creation:

val lastState = searchStackViewModel.currentState()

Answer 1

I have probably resolved this. Turns out that in lifecycle-2.0.0, the ViewModel class has a public method clear():

    @MainThread
    final void clear() {
        mCleared = true;
        // Since clear() is final, this method is still called on mock objects
        // and in those cases, mBagOfTags is null. It'll always be empty though
        // because setTagIfAbsent and getTag are not final so we can skip
        // clearing it
        if (mBagOfTags != null) {
            synchronized (mBagOfTags) {
                for (Object value : mBagOfTags.values()) {
                    // see comment for the similar call in setTagIfAbsent
                    closeWithRuntimeException(value);
                }
            }
        }
        onCleared();
    }

My SearchStackViewModel also has a completely unrelated clear() method.

    /**
     * Clear stack
     */
    fun clear() {
        val current = privateStack.value ?: SearchStack()
        current.clear()
        privateStack.value = current
    }

When minifyEnabled is on, there appears to be a conflict between the two, hence the Linkage error. I renamed my method and the crashes stopped.