Cannot build hello_ar_c sample with AGP 7.0

[fuchg3]

SPECIFIC ISSUE ENCOUNTERED

Cannot correctly build hello_ar_c sample when using Android Gradle Plugin 7.0

Gradle build output:

Executing tasks: [:app:assembleDebug] in project arcore-android-sdk\samples\hello_ar_c

> Task :app:preBuild UP-TO-DATE
> Task :app:preDebugBuild UP-TO-DATE
> Task :app:compileDebugAidl NO-SOURCE
> Task :app:compileDebugRenderscript NO-SOURCE
> Task :app:generateDebugBuildConfig
> Task :app:javaPreCompileDebug
> Task :app:checkDebugAarMetadata
> Task :app:generateDebugResValues
> Task :app:generateDebugResources
> Task :app:createDebugCompatibleScreenManifests
> Task :app:extractDeepLinksDebug
> Task :app:processDebugMainManifest
> Task :app:processDebugManifest
> Task :app:configureCMakeDebug

> Task :app:buildCMakeDebug FAILED
C/C++: ninja: error: '../../../../build/arcore-native/jni/arm64-v8a/libarcore_sdk_c.so', needed by '../../../../build/intermediates/cxx/Debug/211y60f3/obj/arm64-v8a/libhello_ar_native.so', missing and no known rule to make it

> Task :app:extractNativeLibraries
> Task :app:mergeDebugNativeDebugMetadata NO-SOURCE
> Task :app:mergeDebugResources
> Task :app:mergeDebugShaders
> Task :app:compileDebugShaders NO-SOURCE
> Task :app:generateDebugAssets UP-TO-DATE
> Task :app:mergeDebugAssets
> Task :app:processDebugJavaRes NO-SOURCE
> Task :app:compressDebugAssets
> Task :app:mergeDebugJavaResource
> Task :app:desugarDebugFileDependencies
> Task :app:checkDebugDuplicateClasses
> Task :app:mergeDebugJniLibFolders
> Task :app:processDebugManifestForPackage
> Task :app:mergeExtDexDebug
> Task :app:mergeLibDexDebug
> Task :app:mergeDebugNativeLibs
> Task :app:validateSigningDebug
> Task :app:stripDebugDebugSymbols
> Task :app:writeDebugAppMetadata
> Task :app:writeDebugSigningConfigVersions
> Task :app:processDebugResources
> Task :app:compileDebugJavaWithJavac
> Task :app:dexBuilderDebug
> Task :app:mergeProjectDexDebug
> Task :app:packageDebug

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:buildCMakeDebug'.
> Build command failed.
  Error while executing process AppData\Local\Android\Sdk\cmake\3.10.2.4988404\bin\ninja.exe with arguments {-C arcore-android-sdk\samples\hello_ar_c\app\.cxx\Debug\211y60f3\arm64-v8a hello_ar_native}
  ninja: Entering directory `arcore-android-sdk\samples\hello_ar_c\app\.cxx\Debug\211y60f3\arm64-v8a'
  
  ninja: error: '../../../../build/arcore-native/jni/arm64-v8a/libarcore_sdk_c.so', needed by '../../../../build/intermediates/cxx/Debug/211y60f3/obj/arm64-v8a/libhello_ar_native.so', missing and no known rule to make it


* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

Deprecated Gradle features were used in this build, making it incompatible with Gradle 8.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/7.0.2/userguide/command_line_interface.html#sec:command_line_warnings

BUILD FAILED in 1m 6s
32 actionable tasks: 32 executed

It seems task extractNativeLibraries run after task that should depend on it.

VERSIONS USED

• Android Studio: Android Studio Arctic Fox | 2020.3.1
• Android Gradle Plugin: 7.0.0
• Gradle: 7.0.2
• ARCore SDK for Android: 1.26.0
• O/S: Windows 10 21H1

STEPS TO REPRODUCE THE ISSUE

1. Open hello_ar_c sample project in Android Studio
2. Update AGP version to 7.0.0 and Gradle version to 7.0.2
3. Build project

ADDITIONAL COMMENTS

Change

task-> if (task.name.contains("external") && !task.name.contains("Clean"))

to

task-> if (task.name.contains("configureCMake"))

would build successfully. However, sample app crashed due to UnsatisfiedLinkError.

Error logcat:

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.google.ar.core.examples.c.helloar, PID: 13955
    java.lang.UnsatisfiedLinkError: dalvik.system.PathClassLoader[DexPathList[[zip file "/data/app/com.google.ar.core.examples.c.helloar-zrzzeNfjkImFMMLm0cqrww==/base.apk"],nativeLibraryDirectories=[/data/app/com.google.ar.core.examples.c.helloar-zrzzeNfjkImFMMLm0cqrww==/lib/arm64, /data/app/com.google.ar.core.examples.c.helloar-zrzzeNfjkImFMMLm0cqrww==/base.apk!/lib/arm64-v8a, /system/lib64, /hw_product/lib64, /system/product/lib64, /prets/lib64]]] couldn't find "libhello_ar_native.so"
        at java.lang.Runtime.loadLibrary0(Runtime.java:1067)
        at java.lang.Runtime.loadLibrary0(Runtime.java:1007)
        at java.lang.System.loadLibrary(System.java:1668)
        at com.google.ar.core.examples.c.helloar.JniInterface.<clinit>(JniInterface.java:30)
        at com.google.ar.core.examples.c.helloar.HelloArActivity.onCreate(HelloArActivity.java:131)
        at android.app.Activity.performCreate(Activity.java:8214)
        at android.app.Activity.performCreate(Activity.java:8202)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1320)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:4033)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:4247)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:91)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:149)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:103)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2613)
        at android.os.Handler.dispatchMessage(Handler.java:110)
        at android.os.Looper.loop(Looper.java:219)
        at android.app.ActivityThread.main(ActivityThread.java:8668)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:513)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1109)

If you analyzed output apk, you would find libhello_ar_native.so hasn't been packed. Though it do exist in build directory arcore-android-sdk\samples\hello_ar_c\app\build\intermediates\cmake\debug\obj\arm64-v8a.

[fuchg3]

https://issuetracker.google.com/189366123 may be relevant.

[fuchg3]

Probably affected by this issue Android Gradle Plugin 7.0.0 does not include jniLibs in APK if tasks.whenTaskAdded closure is used

Replace tasks.whenTaskAdded closure should fix it, here's my workaround

// Extracts the shared libraries from aars in the natives configuration.
// This is done so that NDK builds can access these libraries.
def taskExtractNativeLibs = tasks.register('extractNativeLibs') {
    // Always extract, this insures the native libs are updated if the version changes.
    outputs.upToDateWhen { false }
    doFirst {
        configurations.natives.files.each { f ->
            copy {
                from zipTree(f)
                into arcore_libpath
                include "jni/**/*"
            }
        }
    }
}

def nativeBuildTasks = tasks.matching { task ->
    task.name.contains('configureCMake')
}

nativeBuildTasks.configureEach { task ->
    task.dependsOn(taskExtractNativeLibs)
}

[devbridie]

Workaround seems great; thanks for investigating. Per issue 196413674#5, it seems like an bugfix update will fix this soon.

[devbridie]

As per 196413674#comment7, this has been cherry picked to 2020.3.1, and I've confirmed that building now works out of the box without the workaround.