java.lang.VerifyError: Bad type on operand stack

[Lonami]

java.lang.VerifyError: Bad type on operand stack

[Lonami]

Thanks a lot for taking the time to look into this. I've created a new project from a Compose template, and after configuring the Rust plugins and uniffi and setting up the NDK version, setup the code necessary to trigger the issue.

I've published the failing code at https://github.com/Lonami/VerifyError-Repro.

Please let me know if you need any more details to import or run the project, or if I can help in any other way. After importing the project, assuming both the NDK and uniffi are configured and installed in the system correctly, it should be possible to open MainActivity.kt in Android Studio and select the Split or Design view (to the right) to trigger the VerifyError during the @Preview of DefaultPreview:

(The squiggly line under Instant.now() is Call requires API level 26 (current min is 21): java.time.Instant#now, which can be safely ignored for this demo.)

The code generated by uniffi-bindgen is placed at app/build/generated/source/uniffi/debug/java/uniffi/verifyerror:

The code generation is done by app/build.gradle (at the bottom of the file, android.applicationVariants.all { ...) and invokes the following command:

commandLine 'uniffi-bindgen', 'generate', '../native/src/verifyerror.udl', '--language', 'kotlin', '--no-format', '--out-dir', "${buildDir}/generated/source/uniffi/${variant.name}/java"

[Lonami]

If I comment out all offending FfiConverter until the preview stops complaining (and replace their uses in method definitions with a TODO()), the @Preview starts working again. I don't think the implementation itself (read, allocationSize and write) have any part on this. It might be the way the sub-classing is defined (as in FfiConverterTypeTextFormat : FfiConverterRustBuffer<TextFormat>). But I really have no idea why it could possibly fail with VerifyError… Maybe it's the way the interface is defined?

interface FfiConverterRustBuffer<KotlinType> : FfiConverter<KotlinType, RustBuffer.ByValue>

But this really seems like a bug in the compiler, perhaps being unable these generics.

What is most strange to me is that the application runs fine when not inside a @Preview.

[badboy]

It's definitely not easily reproducable in just plain Kotlin.
Could you put a full failing example into a repository so I can run and test it? Might be easier than me trying to piece together the parts to get it to build. I'm happy to take a look then.

[badboy]

I spent a bit of time on it this morning. I am able to reproduce it using the provided code.
I'm fairly sure now this is some miscompilation in whatever does the preview rendering.
I don't think the uniffi code is inherently wrong. But I also don't know where the buggy behavior is hiding.

Unfortunately I can't spent much more time on this right now.

[Lonami]

Thanks, yeah, it's probably safe to close this issue as the bug is unlikely to be uniffi's fault (technically, I'm sure the code could be generated in a different way to not trigger this problem, but that's a workaround and not the right solution).

[Lonami]

The repository I mentioned earlier was deleted but here's the main contents of the files:

MainActivity.kt

package com.example.verifyerror

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.material.MaterialTheme
import androidx.compose.material.Surface
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.tooling.preview.Preview
import com.example.verifyerror.ui.theme.VerifyErrorReproTheme
import uniffi.verifyerror.Message
import java.time.Instant

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            VerifyErrorReproTheme {
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colors.background
                ) {
                    Greeting("Android")
                }
            }
        }
    }
}

@Composable
fun Greeting(name: String) {
    Text(text = "Hello $name!")
}

@Preview(showBackground = true)
@Composable
fun DefaultPreview() {
    val msg = remember {
        Message(
            id = 1,
            sender = "Alice",
            text = "Testing",
            date = Instant.now(),
            editDate = null,
            formatting = listOf(),
        )
    }

    Text(text = msg.text)
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.VerifyErrorRepro"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true"
            android:label="@string/app_name"
            android:theme="@style/Theme.VerifyErrorRepro">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <meta-data
                android:name="android.app.lib_name"
                android:value="" />
        </activity>
    </application>

</manifest>

build.gradle

plugins {
    id 'com.android.application'
    id 'org.jetbrains.kotlin.android'
    id "org.mozilla.rust-android-gradle.rust-android"
}

android {
    namespace 'com.example.verifyerror'
    compileSdk 32

    defaultConfig {
        applicationId "com.example.verifyerror"
        minSdk 21
        targetSdk 32
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
        vectorDrawables {
            useSupportLibrary true
        }
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
    buildFeatures {
        compose true
    }
    composeOptions {
        kotlinCompilerExtensionVersion '1.1.1'
    }
    packagingOptions {
        resources {
            excludes += '/META-INF/{AL2.0,LGPL2.1}'
        }
    }
    ndkVersion '25.1.8937393'
}

dependencies {

    implementation 'androidx.core:core-ktx:1.7.0'
    implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.3.1'
    implementation 'androidx.activity:activity-compose:1.3.1'
    implementation "androidx.compose.ui:ui:$compose_ui_version"
    implementation "androidx.compose.ui:ui-tooling-preview:$compose_ui_version"
    implementation 'androidx.compose.material:material:1.1.1'
    implementation "net.java.dev.jna:jna:5.12.0@aar"
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
    androidTestImplementation "androidx.compose.ui:ui-test-junit4:$compose_ui_version"
    debugImplementation "androidx.compose.ui:ui-tooling:$compose_ui_version"
    debugImplementation "androidx.compose.ui:ui-test-manifest:$compose_ui_version"
}

cargo {
    module = "../native"
    libname = "uniffi_verifyerror"
    targets = ["arm64"]
    profile = 'release'
}

tasks.whenTaskAdded { task ->
    if ((task.name == 'javaPreCompileDebug' || task.name == 'javaPreCompileRelease')) {
        task.dependsOn 'cargoBuild'
    }
}

android.applicationVariants.all { variant ->
    def t = tasks.register("generate${variant.name.capitalize()}UniFFIBindings", Exec) {
        workingDir "${project.projectDir}"
        commandLine 'uniffi-bindgen', 'generate', '../native/src/verifyerror.udl', '--language', 'kotlin', '--no-format', '--out-dir', "${buildDir}/generated/source/uniffi/${variant.name}/java"
    }
    variant.javaCompileProvider.get().dependsOn(t)
    def sourceSet = variant.sourceSets.find { it.name == variant.name }
    sourceSet.java.srcDir new File(buildDir, "generated/source/uniffi/${variant.name}/java")
}

Maybe this can be closed as stale.