From e07b2e30e2789a7110e3b861cbb63c5ff0de5c0e Mon Sep 17 00:00:00 2001
From: Ivan Gavrilovic <gavra@google.com>
Date: Tue, 15 Oct 2019 19:27:06 +0100
Subject: [PATCH] KT-34258: Make sure to clean up stale files even if no Kotlin
 sources

If running incrementally, even if there aren't any Kotlin sources to
compile, there could be stale output files that need to be removed. E.g
stub generation must have generated .java files removed if all Kotlin
sources are removed. Kotlin compile task will be skipped only if there
are no Kotlin sources and task run is non-incremental.

Test: KaptIncrementalIT.testRemoveAllKotlinSources
---
 .../kotlin/gradle/KaptIncrementalIT.kt        | 35 ++++++++++++++++---
 .../jetbrains/kotlin/gradle/tasks/Tasks.kt    |  3 +-
 2 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/KaptIncrementalIT.kt b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/KaptIncrementalIT.kt
index 9c51178b7e3..9bdd60cca8b 100644
--- a/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/KaptIncrementalIT.kt
+++ b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/KaptIncrementalIT.kt
@@ -1,10 +1,8 @@
 package org.jetbrains.kotlin.gradle
 
-import org.jetbrains.kotlin.gradle.util.allKotlinFiles
-import org.jetbrains.kotlin.gradle.util.findFileByName
-import org.jetbrains.kotlin.gradle.util.getFileByName
-import org.jetbrains.kotlin.gradle.util.modify
+import org.jetbrains.kotlin.gradle.util.*
 import org.junit.Test
+import kotlin.test.assertEquals
 
 open class KaptIncrementalIT : BaseGradleIT() {
     companion object {
@@ -204,6 +202,35 @@ open class KaptIncrementalIT : BaseGradleIT() {
         }
     }
 
+    @Test
+    fun testRemoveAllKotlinSources() {
+        val project = getProject()
+        val kapt3StubsPath = "build/tmp/kapt3/stubs/main"
+
+        project.build("build") {
+            assertSuccessful()
+            assertKapt3FullyExecuted()
+        }
+
+        with(project.projectDir) {
+            resolve("src/main/java").deleteRecursively()
+            resolve("src/main/java/bar").mkdirs()
+            resolve("src/main/java/bar/MyClass.java").writeText(
+                """
+                package bar;
+                public class MyClass {}
+            """.trimIndent()
+            )
+        }
+
+        project.build("build") {
+            assertSuccessful()
+
+            // Make sure all stubs are removed
+            assertEquals(emptyList(), fileInWorkingDir(kapt3StubsPath).walk().filter { it.extension == "java" }.toList())
+        }
+    }
+
     @Test
     fun testRemoveAnnotations() {
         val project = getProject()
diff --git a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/Tasks.kt b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/Tasks.kt
index 31f76b2236f..0931274bdba 100644
--- a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/Tasks.kt
+++ b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/Tasks.kt
@@ -296,7 +296,8 @@ abstract class AbstractKotlinCompile<T : CommonCompilerArguments>() : AbstractKo
 
         logger.kotlinDebug { "All kotlin sources: ${allKotlinSources.pathsAsStringRelativeTo(project.rootProject.projectDir)}" }
 
-        if (allKotlinSources.isEmpty()) {
+        if (!inputs.isIncremental && allKotlinSources.isEmpty()) {
+            // Skip running only if non-incremental run. Otherwise, we may need to do some cleanup.
             logger.kotlinDebug { "No Kotlin files found, skipping Kotlin compiler task" }
             return
         }