Default Values for Composable functions in Interfaces crash at runtime when overriden [317490247]

Duplicate

of 165812010

Bug

Status Update

No update yet.

Description

ma...@gmail.com

created issue #1

Dec 22, 2023 09:20PM

Setting default parameters in a Composable function in an Interface, and then overriding it will crash at runtime with a null value for those parameters. According to Ben Trengrove on Kotlin slack "I should add as well, default values in composable interface functions are currently not supported. The compiler should be picking that up at compile time though, not runtime."

Jetpack Compose version: Compiler 1.5.7 androidx.compose:compose-bom:2023.10.01

Jetpack Compose component(s) used: Compiler/Runtime Android Studio Build: Android Studio Hedgehog | 2023.1.1

Kotlin version: 1.9.21

Steps to Reproduce or Code Sample to Reproduce:

package com.example.myapplication

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val fooBar = FooBar()
        setContent {
            //Runtime Crash
            fooBar.Bar()
        }
    }
}

class FooBar : Foo {
    @Composable
    override fun Bar(modifier: Modifier) {
        println("Bar $modifier")
    }
}


interface Foo {
    //This will crash if overridden and called with the default value
    @Composable
    fun Bar(modifier: Modifier = Modifier) {
        println("$modifier")

    }
}

Stack trace (if applicable):

 java.lang.NullPointerException: Parameter specified as non-null is null: method com.example.myapplication.FooBar.Bar, parameter modifier
                                                                                                    	at com.example.myapplication.FooBar.Bar(Unknown Source:2)
                                                                                                    	at com.example.myapplication.MainActivity$onCreate$1.invoke(MainActivity.kt:22)
                                                                                                    	at com.example.myapplication.MainActivity$onCreate$1.invoke(MainActivity.kt:21)
                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:108)
                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
                                                                                                    	at androidx.compose.ui.platform.ComposeView.Content(ComposeView.android.kt:428)
                                                                                                    	at androidx.compose.ui.platform.AbstractComposeView$ensureCompositionCreated$1.invoke(ComposeView.android.kt:252)
                                                                                                    	at androidx.compose.ui.platform.AbstractComposeView$ensureCompositionCreated$1.invoke(ComposeView.android.kt:251)
                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:108)
                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
                                                                                                    	at androidx.compose.runtime.CompositionLocalKt.CompositionLocalProvider(CompositionLocal.kt:228)
                                                                                                    	at androidx.compose.ui.platform.CompositionLocalsKt.ProvideCommonCompositionLocals(CompositionLocals.kt:195)
                                                                                                    	at androidx.compose.ui.platform.AndroidCompositionLocals_androidKt$ProvideAndroidCompositionLocals$3.invoke(AndroidCompositionLocals.android.kt:119)
                                                                                                    	at androidx.compose.ui.platform.AndroidCompositionLocals_androidKt$ProvideAndroidCompositionLocals$3.invoke(AndroidCompositionLocals.android.kt:118)
                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:108)
                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
                                                                                                    	at androidx.compose.runtime.CompositionLocalKt.CompositionLocalProvider(CompositionLocal.kt:228)
                                                                                                    	at androidx.compose.ui.platform.AndroidCompositionLocals_androidKt.ProvideAndroidCompositionLocals(AndroidCompositionLocals.android.kt:110)
                                                                                                    	at androidx.compose.ui.platform.WrappedComposition$setContent$1$1$2.invoke(Wrapper.android.kt:158)
                                                                                                    	at androidx.compose.ui.platform.WrappedComposition$setContent$1$1$2.invoke(Wrapper.android.kt:157)
                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:108)
                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
                                                                                                    	at androidx.compose.runtime.CompositionLocalKt.CompositionLocalProvider(CompositionLocal.kt:228)
                                                                                                    	at androidx.compose.ui.platform.WrappedComposition$setContent$1$1.invoke(Wrapper.android.kt:157)
                                                                                                    	at androidx.compose.ui.platform.WrappedComposition$setContent$1$1.invoke(Wrapper.android.kt:142)
                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:108)
                                                                                                    	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)

Comments

ad...@google.com <ad...@google.com> Dec 25, 2023 11:58PM

Assigned to je...@google.com.

as...@google.com <as...@google.com> Jan 2, 2024 08:00PM

Reassigned to as...@google.com.

as...@google.com <as...@google.com> #2Jan 2, 2024 11:49PM

After some investigation, is seems like we restrict defaults for abstract functions, but don't do so for open ones. Long-term, we need to support this code shape, short-term we likely want to restrict these.

ap...@google.com <ap...@google.com> #3Jan 4, 2024 06:25PM

Project: platform/frameworks/support
Branch: androidx-main

commit 349bcc021df2ec23df85344bd67468bf1140579c
Author: Andrei Shikov <ashikov@google.com>
Date: Tue Jan 02 23:57:19 2024

Restrict default parameters on open composable functions

Compose doesn't support substituting default parameters from overridden functions and currently restricts abstract functions from using default params. This change expands this restriction to open functions, which were previously ignored.

Relnote: """Add a compilation error for default parameters in open functions (previously only it was restricted only for abstract functions). Compose does not support substitution of default parameters from overridden functions at the moment, and overriding a composable function with default parameters was failing at runtime. Use `@Suppress("ABSTRACT_COMPOSABLE_DEFAULT_PARAMETER_VALUE") to suppress, but note that overriding such function without providing a default value for parameter will result in a crash at runtime. """

Bug: 317490247
Change-Id: Iaa00663f630e51900341b9603b368dfc54662582

M compose/compiler/compiler-hosted/integration-tests/src/jvmTest/kotlin/androidx/compose/compiler/plugins/kotlin/analysis/ComposableDeclarationCheckerTests.kt
M compose/compiler/compiler-hosted/src/main/java/androidx/compose/compiler/plugins/kotlin/k1/ComposableDeclarationChecker.kt
M compose/compiler/compiler-hosted/src/main/java/androidx/compose/compiler/plugins/kotlin/k1/ComposeErrorMessages.kt
M compose/compiler/compiler-hosted/src/main/java/androidx/compose/compiler/plugins/kotlin/k2/ComposableFunctionChecker.kt
M compose/compiler/compiler-hosted/src/main/java/androidx/compose/compiler/plugins/kotlin/k2/ComposeErrorMessages.kt
M compose/material/material/api/current.txt
M compose/material/material/api/restricted_current.txt
M compose/material/material/src/androidMain/kotlin/androidx/compose/material/ExposedDropdownMenu.android.kt
M compose/material3/material3/api/1.2.0-beta02.txt
M compose/material3/material3/api/current.txt
M compose/material3/material3/api/restricted_1.2.0-beta02.txt
M compose/material3/material3/api/restricted_current.txt
M compose/material3/material3/src/androidMain/kotlin/androidx/compose/material3/ExposedDropdownMenu.android.kt

https://android-review.googlesource.com/2894244

Ch...@esolutions.de <Ch...@esolutions.de> #4Feb 12, 2024 01:18PM

I had the same issue, when I wanted to provide a unified library API for different OEMs using interfaces/abstract classes with default parameters.

Note that restricting defaults on abstract/open functions is not consistent with the way kotlin handles default parameters override (which could be suprising for other users):

https://kotlinlang.org/docs/functions.html#default-arguments

But at least having a compile time error would be better

as...@google.com <as...@google.com> Apr 3, 2024 06:01PM

Status: Duplicate of

165812010

Issue 317490247