[KAPT] Skip kapt tasks if no annotations processors are provided (#4190)

So we don't do any preparation, don't spin up compiler.  And user will see SKIPPED in task execution

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/kapt/Kapt3KotlinGradleSubplugin.kt

@@ -525,6 +525,13 @@ class Kapt3GradleSubplugin @Inject internal constructor(private val registry: To
             registerSubpluginOptions(kaptTaskProvider, subpluginOptions)
         }
 
+        kaptTaskProvider.configure { task ->
+            task.onlyIf {
+                it as KaptTask
+                it.includeCompileClasspath || !it.kaptClasspath.isEmpty()
+            }
+        }
+
         return kaptTaskProvider
     }
 
@@ -568,6 +575,12 @@ class Kapt3GradleSubplugin @Inject internal constructor(private val registry: To
             kaptTask.kaptClasspathConfigurations = kaptClasspathConfigurations
 
             PropertiesProvider(project).mapKotlinTaskProperties(kaptTask)
+
+            if (!includeCompileClasspath) {
+                kaptTask.onlyIf {
+                    !(it as KaptGenerateStubsTask).kaptClasspath.isEmpty()
+                }
+            }
         }
 
         project.whenEvaluated {

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/kapt/KaptWithoutKotlincTask.kt

@@ -119,8 +119,10 @@ abstract class KaptWithoutKotlincTask @Inject constructor(private val workerExec
         )
 
         // Skip annotation processing if no annotation processors were provided.
-        if (annotationProcessorFqNames.isEmpty() && kaptClasspath.isEmpty())
+        if (annotationProcessorFqNames.isEmpty() && kaptClasspath.isEmpty()) {
+            logger.info("No annotation processors provided. Skip KAPT processing.")
             return
+        }
 
         val kaptClasspath = kaptJars + kotlinStdlibClasspath
 
@@ -301,4 +303,4 @@ internal data class KaptOptionsForWorker(
     val javacOptions: Map<String, String>,
 
     val flags: Set<String>
-) : Serializable
+) : Serializable

plugins/kapt3/kapt3-compiler/src/org/jetbrains/kotlin/kapt3/Kapt3Plugin.kt

@@ -209,6 +209,7 @@ class Kapt3ComponentRegistrar : ComponentRegistrar {
         if (processingClasspath.isEmpty()) {
             // Skip annotation processing if no annotation processors were provided
             if (mode != AptMode.WITH_COMPILATION) {
+                logger.info("No annotation processors provided. Skip KAPT processing.")
                 abortAnalysis()
             }
             return false
@@ -274,4 +275,4 @@ class Kapt3ComponentRegistrar : ComponentRegistrar {
             return AnalysisResult.success(bindingTrace.bindingContext, module, shouldGenerateCode = false)
         }
     }
-}
+}