Remove generated sources and classes for full KAPT build

When running incremental annotation processing in KAPT,
even if incremental flag is enabled, and full rebuild should
be performed (e.g. in presence of dynamic non-incremental APs),
make sure generated sources and classes are removed.

 #KT-31322 fixed

plugins/kapt3/kapt3-base/src/org/jetbrains/kotlin/kapt3/base/KaptContext.kt

@@ -64,6 +64,14 @@ open class KaptContext(val options: KaptOptions, val withJdk: Boolean, val logge
                 cacheManager?.invalidateAndGetDirtyFiles(
                     options.changedFiles, options.classpathChanges
                 ) ?: SourcesToReprocess.FullRebuild
+
+            if (sourcesToReprocess == SourcesToReprocess.FullRebuild) {
+                // remove all generated sources and classes
+                options.sourcesOutputDir.deleteRecursively()
+                options.sourcesOutputDir.mkdir()
+                options.classesOutputDir.deleteRecursively()
+                options.classesOutputDir.mkdir()
+            }
         } else {
             sourcesToReprocess = SourcesToReprocess.FullRebuild
         }

plugins/kapt3/kapt3-base/test/org/jetbrains/kotlin/kapt3/base/incremental/IncrementalKaptTest.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.base.kapt3.KaptOptions
 import org.jetbrains.kotlin.base.kapt3.collectJavaSourceFiles
 import org.jetbrains.kotlin.kapt3.base.KaptContext
 import org.jetbrains.kotlin.kapt3.base.doAnnotationProcessing
+import org.jetbrains.kotlin.kapt3.base.incremental.RuntimeProcType
 import org.jetbrains.kotlin.kapt3.base.incremental.SourcesToReprocess
 import org.jetbrains.kotlin.kapt3.base.util.WriterBackedKaptLogger
 import org.junit.Assert.*
@@ -160,4 +161,67 @@ class IncrementalKaptTest {
 
         assertTrue(outputDir.resolve("test/UserGenerated.java").exists())
     }
+
+    /** Regression test for KT-31322. */
+    @Test
+    fun testCleanupWithDynamicNonIncremental() {
+        val sourcesDir = tmp.newFolder().resolve("test").also { base ->
+            base.mkdir()
+            listOf("User.java", "Address.java", "Observable.java").map {
+                TEST_DATA_DIR.resolve(it).copyTo(base.resolve(it))
+            }
+        }
+
+        val outputDir = tmp.newFolder()
+        val incrementalCacheDir = tmp.newFolder()
+        val options = KaptOptions.Builder().apply {
+            projectBaseDir = tmp.newFolder()
+            javaSourceRoots.add(sourcesDir)
+
+            sourcesOutputDir = outputDir
+            classesOutputDir = outputDir
+            stubsOutputDir = outputDir
+            incrementalDataOutputDir = outputDir
+
+            incrementalCache = incrementalCacheDir
+        }.build()
+
+        val logger = WriterBackedKaptLogger(isVerbose = true)
+        KaptContext(options, true, logger).use {
+            it.doAnnotationProcessing(
+                options.collectJavaSourceFiles(SourcesToReprocess.FullRebuild),
+                listOf(DynamicProcessor(RuntimeProcType.NON_INCREMENTAL).toDynamic())
+            )
+        }
+
+        val optionsForSecondRun = KaptOptions.Builder().apply {
+            projectBaseDir = tmp.newFolder()
+            javaSourceRoots.add(sourcesDir)
+
+            sourcesOutputDir = outputDir
+            classesOutputDir = outputDir
+            stubsOutputDir = outputDir
+            incrementalDataOutputDir = outputDir
+
+            incrementalCache = incrementalCacheDir
+            changedFiles.add(sourcesDir.resolve("User.java"))
+            flags.add(KaptFlag.INCREMENTAL_APT)
+        }.build()
+
+        KaptContext(optionsForSecondRun, true, logger).use {
+            val sourcesToReprocess =
+                it.cacheManager!!.invalidateAndGetDirtyFiles(optionsForSecondRun.changedFiles, emptyList())
+            assertEquals(SourcesToReprocess.FullRebuild, sourcesToReprocess)
+
+            // check output dir is empty
+            assertEquals(listOf(outputDir), outputDir.walkTopDown().toList())
+
+            it.doAnnotationProcessing(
+                optionsForSecondRun.collectJavaSourceFiles(sourcesToReprocess),
+                listOf(DynamicProcessor(RuntimeProcType.NON_INCREMENTAL).toDynamic())
+            )
+        }
+
+        assertTrue(outputDir.resolve("test/UserGenerated.java").exists())
+    }
 }