IssueTracker

I can't reproduce this. Can you attach a project where you see it?

The error raised from here: https://cs.android.com/android-studio/kotlin/+/master:compiler/light-classes/src/org/jetbrains/kotlin/asJava/classes/KtLightClassForFacadeImpl.kt;l=248?q=KtLightClassForFacadeImpl

But, assuming there is no script file, the only case ULC fails to create a facade light class is here: https://cs.android.com/android-studio/kotlin/+/master:compiler/light-classes/src/org/jetbrains/kotlin/asJava/LightClassGenerationSupport.kt;l=71?q=createUltraLightClassForFacade which seems like a configuration issue.

Not trivial to reproduce the case in upstream Kotiln/IntelliJ repo.

There is a similar input: https://github.com/JetBrains/kotlin/blob/master/compiler/testData/asJava/lightClasses/facades/EmptyFile.NoCompile.kt but not entirely empty. Even after making it completely empty, the corresponding test won't exercise a similar facade LC creation. U/LC is heavily tested in IJ repo instead, where IDE version of KotlinAsJavaSupport, not CliKotlinAsJavaSupport, is used, which has a quite different way of creating a facade light class (in short, decompilation): https://github.com/JetBrains/intellij-community/blob/master/plugins/kotlin/analysis/src/org/jetbrains/kotlin/idea/caches/resolve/IDEKotlinAsJavaSupport.kt#L211

I tried to to fix ^H^H^H work around this issue -- by just having lint skip empty files since there's no good reason to analyze them anyway:

diff --git a/lint/libs/lint-api/src/main/java/com/android/tools/lint/helpers/DefaultUastParser.kt b/lint/libs/lint-api/src/main/java/com/android/tools/lint/helpers/DefaultUastParser.kt
index 27ae062dd78..7a1af09b48b 100644
--- a/lint/libs/lint-api/src/main/java/com/android/tools/lint/helpers/DefaultUastParser.kt
+++ b/lint/libs/lint-api/src/main/java/com/android/tools/lint/helpers/DefaultUastParser.kt
@@ -121,6 +121,11 @@ open class DefaultUastParser(
                 StandardFileSystems.local().findFileByPath(absPath) ?: return null
             }

+        // Workaround for b/233355652
+        if (virtualFile.length == 0L) {
+            return null
+        }
+
         val psiFile = PsiManager.getInstance(ideaProject).findFile(virtualFile) ?: return null

         if (psiFile.language == Language.ANY && file.path.endsWith(DOT_KT)) {

But while that "fixes" the immediate exception shown in repro project (thank you very much for that repro project by the way, very helpful!), it just shifts the problem, because the mere presence of that file no the class path causes the PSI environment to look it up on its own later and fail -- for example from this code path:

kotlin.UninitializedPropertyAccessException: lateinit property module has not been initialized
        at org.jetbrains.kotlin.cli.jvm.compiler.CliTraceHolder.getModule(CliTrace.kt:25)
        at org.jetbrains.kotlin.cli.jvm.compiler.CliKotlinAsJavaSupport.findClassOrObjectDeclarations(CliKotlinAsJavaSupport.kt:119)
        at org.jetbrains.kotlin.asJava.finder.JavaElementFinder.findClassesAndObjects(JavaElementFinder.kt:62)
        at org.jetbrains.kotlin.asJava.finder.JavaElementFinder.findClasses(JavaElementFinder.kt:47)
        at org.jetbrains.kotlin.asJava.finder.JavaElementFinder.findClass(JavaElementFinder.kt:36)
        at com.intellij.psi.impl.JavaPsiFacadeImpl.doFindClass(JavaPsiFacadeImpl.java:91)
        at com.intellij.psi.impl.JavaPsiFacadeImpl.findClass(JavaPsiFacadeImpl.java:69)
        at com.android.tools.lint.helpers.DefaultJavaEvaluator.findClass(DefaultJavaEvaluator.kt:99)

So we'll need to get to the bottom of it properly.

We are hitting the lateinit exception in AndroidX in b/235966443 as well, if you need any additional data points. I'm currently looking into whether it's related to empty files.

We started hitting androidx failure after upgrading to AGP 7.4.0-alpha04 from AGP 7.4.0-alpha01.

Examples of this failure in our CI

This is bad enough for us to revert back to alpha01

Do you have empty .kt files?

Yes, CL to delete them is up now (https://android-review.googlesource.com/c/platform/frameworks/support/+/2125525)

Last time I was able to detach to the repro project build, I saw the facade light class "EmptyKt" for "empty.kt" is created properly. Rather, what triggered the whole exception trace was "Build_gradleKt", which I guess came from "build_gradle.kt" somewhere. Does anyone notice about this? Anyway, then I lost the control; let me try again today.

Regarding the revert, sorry to hear that. But, there wasn't any major UAST drops since 7.4.0-alpha01. Well, from upstream UAST. On the platform side, everything is updated to IJ 221 recently?

Finally, I got to the bottom of this, and was able to reproduce it in Android Lint testing infra, which is surprisingly simple:

    @Test
    fun testEmptyKtWithGradleKts() {
        TestLintTask.lint().files(
            kts(
                """
                plugins {
                  id("com.android.application")
                }
                """.trimIndent()
            ),
            kotlin(
                "src/some/pkg/Empty.kt",
                ""
            )
        )
            .allowMissingSdk()
            .issues(UastImplementationDetector.ISSUE) // Any detector that triggers FILE-level UAST visit
            .run()
            .expectClean()
    }

Any detector that needs to visit UFile triggers collecting facade light classes in that file. Under the hood, such collection is package name-based lookup. As an empty file, its package name is <root> for now. build.gradle.kts, as a script file, has <root> package too.

At comment #4, I said:

But, assuming there is no script file, the only case ULC fails to create a facade light class is here: https://cs.android.com/android-studio/kotlin/+/master:compiler/light-classes/src/org/jetbrains/kotlin/asJava/LightClassGenerationSupport.kt;l=71?q=createUltraLightClassForFacade

Well, there is script file :( and thus null is returned just a couple lines below: https://cs.android.com/android-studio/kotlin/+/master:compiler/light-classes/src/org/jetbrains/kotlin/asJava/LightClassGenerationSupport.kt;l=73?q=createUltraLightClassForFacade

That is, upstream U/LC has an incomplete condition check 1 that asks to build U/LC facade for script file, and raises an error as it can't generate such facade. :o I'll file a YT issue and fix that at upstream U/LC level.

it just shifts the problem, because the mere presence of that file no the class path causes the PSI environment to look it up on its own later and fail

Yeah, but it's not just an empty .kt file; any .kt files without specific package names could have triggered the issue. So... I'm still not sure a nice workaround on Android Lint side.

Here is the upstream issue: https://youtrack.jetbrains.com/issue/KTIJ-22016/

Regarding workaround, it's too deep in U/LC facade creation, and like I said, this could be triggered by any root-level file:

    @Test
    fun testNonEmptyRootPackageKtWithGradleKts() {
        TestLintTask.lint().files(
            kts(
                """
                plugins {
                  id("com.android.application")
                }
                """.trimIndent()
            ),
            kotlin(
                "src/NonEmpty.kt",
                "val p = 42"
            )
        )
            .allowMissingSdk()
            .issues(UastImplementationDetector.ISSUE) // Any detector that triggers FILE-level UAST visit
            .run()
            .expectClean()
    }

An upstream fix should be simple, so I'd rather patch that directly to Lint's bundled PSI artifacts.

Re: comment#6,

I've tried the same workaround:

+        // Workaround for b/233355652
+        if (virtualFile.length == 0L) {
+            return null
+        }

to see if I'd see the same lateinit exception, but the lintDebug task failed differently:

.../secant-android-wallet/test-lib/src/main/AndroidManifest.xml:6: Error: android.permission.WAKE_LOCK is a reserved permission [ReservedSystemPermission]
    <permission android:name="android.permission.WAKE_LOCK"/>
                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

   Explanation for issues of type "ReservedSystemPermission":
   This check looks for custom permission declarations whose names are
   reserved values for system or Android SDK permissions.

   Please double check the permission name you have supplied. Attempting to
   redeclare a system or Android SDK permission will be ignored.

which seems like b/232652234 or indeed an issue in the repro project. Commenting out that permission line was good enough to proceed, and lint succeeded.

So, I'm curious what the full stack trace was, because one from https://android-build-admin.corp.google.com/build?build_id=P36264724&target=androidx_incremental looks like:

  kotlin.UninitializedPropertyAccessException: lateinit property module has not been initialized
  	at org.jetbrains.kotlin.cli.jvm.compiler.CliTraceHolder.getModule(CliTrace.kt:25)
  	at org.jetbrains.kotlin.cli.jvm.compiler.CliKotlinAsJavaSupport.findClassOrObjectDeclarations(CliKotlinAsJavaSupport.kt:119)
  	at org.jetbrains.kotlin.asJava.finder.JavaElementFinder.findClassesAndObjects(JavaElementFinder.kt:62)
  	at org.jetbrains.kotlin.asJava.finder.JavaElementFinder.findClasses(JavaElementFinder.kt:47)
  	at org.jetbrains.kotlin.asJava.finder.JavaElementFinder.findClass(JavaElementFinder.kt:36)
  	at com.intellij.psi.impl.JavaPsiFacadeImpl.doFindClass(JavaPsiFacadeImpl.java:91)
  	at com.intellij.psi.impl.JavaPsiFacadeImpl.findClass(JavaPsiFacadeImpl.java:69)
  	at com.android.tools.lint.helpers.DefaultJavaEvaluator.findClass(DefaultJavaEvaluator.kt:99)
  	at com.android.tools.lint.checks.PermissionErrorDetector$Companion.computePlatformPermissions(PermissionErrorDetector.kt:463)
  	at com.android.tools.lint.checks.PermissionErrorDetector$Companion.getPlatformPermissions(PermissionErrorDetector.kt:453)
  	at com.android.tools.lint.checks.PermissionErrorDetector$Companion.findAlmostPlatformPermission(PermissionErrorDetector.kt:342)
  	at com.android.tools.lint.checks.PermissionErrorDetector.reportPermissionUsageIncidents(PermissionErrorDetector.kt:191)
  	at com.android.tools.lint.checks.PermissionErrorDetector.checkDocument$reportOrAddPermissionUsages(PermissionErrorDetector.kt:78)
  	at com.android.tools.lint.checks.PermissionErrorDetector.checkDocument(PermissionErrorDetector.kt:91)
  	at com.android.tools.lint.checks.PermissionErrorDetector.checkMergedProject(PermissionErrorDetector.kt:58)
  	at com.android.tools.lint.client.api.LintDriver.processMergedProjects(LintDriver.kt:676)
  	at com.android.tools.lint.LintCliClient.mergeState(LintCliClient.kt:616)
  	at com.android.tools.lint.client.api.LintDriver$LintClientWrapper.mergeState(LintDriver.kt:2952)
  	at com.android.tools.lint.client.api.LintDriver$mergeOnly$1.invoke(LintDriver.kt:483)
  	at com.android.tools.lint.client.api.LintDriver$mergeOnly$1.invoke(LintDriver.kt:478)
  	at com.android.tools.lint.client.api.LintDriver.doAnalyze$default(LintDriver.kt:493)
  	at com.android.tools.lint.client.api.LintDriver.mergeOnly(LintDriver.kt:478)
  	at com.android.tools.lint.LintCliClient$mergeOnly$1.invoke(LintCliClient.kt:262)
  	at com.android.tools.lint.LintCliClient$mergeOnly$1.invoke(LintCliClient.kt:260)
  	at com.android.tools.lint.LintCliClient.mergeOnly(LintCliClient.kt:260)

Note that that detector, PermissionErrorDetector, and functions involved in the stacktrace were indeed changed recently: http://ag/18425782 and http://ag/18440844. So... I'm not sure empty kt files were the root cause of uninitialized module variable in CliTraceHolder.

I have an attempt to reland AGP 7.4.0-alpha04 https://android-review.googlesource.com/c/platform/prebuilts/androidx/external/+/2128073 now that we have no empty files. That should verify if thats the same bug or not.

From the upstream related issue, I found that someone already saw a similar error coming from the file at the top-level package: https://github.com/HaukeRa/kotlin-lint-error-reproducer/blob/master/src/main/java/Test.kt

Created b/236262744 because we are still crashing without empty files.

Upstream issue (comment #13) is fixed early this week, targeting 2021.3-1.7.20. However, it usually takes long to catch up upstream PSI/UAST changes in Kotlin/IJ. So we added a local patch to PSI artifacts bundled to Android Lint. It'll be available at the next canary (AS EE / AGP 7.4 canary 7?).

Thanks for the fix!

FYI, internal reference: https://googleplex-android-review.git.corp.google.com/q/topic:lint-patch-empty-kt-files

aaltafgopang86 @gmail com

If it can help others, I also get this issue if the Kotlin file is missing a package declaration. Adding it fixes the issue.

I'm not sure what version of AS you're using, but assuming a stable version, maybe Dolphin?

It'll be available at the next canary (AS EE / AGP 7.4 canary 7?).

Like I mentioned, a patch is added and available in EE, and its stable version will be out very soon.