Support using Java-repeatable annotations in Kotlin

#KT-12794

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/checkers/RepeatableAnnotationChecker.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.resolve.jvm.checkers
 
+import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationUseSiteTarget
 import org.jetbrains.kotlin.descriptors.annotations.KotlinRetention
@@ -19,13 +20,17 @@ import org.jetbrains.kotlin.resolve.descriptorUtil.getAnnotationRetention
 import org.jetbrains.kotlin.resolve.descriptorUtil.isRepeatableAnnotation
 import org.jetbrains.kotlin.resolve.jvm.diagnostics.ErrorsJvm
 
-object RepeatableAnnotationChecker : AdditionalAnnotationChecker {
+class RepeatableAnnotationChecker(languageVersionSettings: LanguageVersionSettings) : AdditionalAnnotationChecker {
+    private val nonSourceDisallowed = !languageVersionSettings.supportsFeature(LanguageFeature.RepeatableAnnotations)
+
     override fun checkEntries(
         entries: List<KtAnnotationEntry>,
         actualTargets: List<KotlinTarget>,
         trace: BindingTrace,
         languageVersionSettings: LanguageVersionSettings
     ) {
+        if (entries.isEmpty()) return
+
         val entryTypesWithAnnotations = hashMapOf<FqName, MutableList<AnnotationUseSiteTarget?>>()
 
         for (entry in entries) {
@@ -42,7 +47,9 @@ object RepeatableAnnotationChecker : AdditionalAnnotationChecker {
                 && classDescriptor.isRepeatableAnnotation()
                 && classDescriptor.getAnnotationRetention() != KotlinRetention.SOURCE
             ) {
-                trace.report(ErrorsJvm.NON_SOURCE_REPEATED_ANNOTATION.on(entry))
+                if (nonSourceDisallowed) {
+                    trace.report(ErrorsJvm.NON_SOURCE_REPEATED_ANNOTATION.on(entry))
+                }
             }
 
             existingTargetsForAnnotation.add(useSiteTarget)

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/diagnostics/DefaultErrorMessagesJvm.java

@@ -71,7 +71,7 @@ public class DefaultErrorMessagesJvm implements DefaultErrorMessages.Extension {
 
         MAP.put(POSITIONED_VALUE_ARGUMENT_FOR_JAVA_ANNOTATION, "Only named arguments are available for Java annotations");
         MAP.put(DEPRECATED_JAVA_ANNOTATION, "This annotation is deprecated in Kotlin. Use ''@{0}'' instead", TO_STRING);
-        MAP.put(NON_SOURCE_REPEATED_ANNOTATION, "Repeatable annotations with non-SOURCE retention are not yet supported");
+        MAP.put(NON_SOURCE_REPEATED_ANNOTATION, "Repeatable annotations with non-SOURCE retention are only supported starting from Kotlin 1.6");
         MAP.put(ANNOTATION_IS_NOT_APPLICABLE_TO_MULTIFILE_CLASSES, "Annotation ''@{0}'' is not applicable to the multi-file classes", TO_STRING);
 
         MAP.put(JVM_PACKAGE_NAME_CANNOT_BE_EMPTY, "''@JvmPackageName'' annotation value cannot be empty");

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/platform/JvmPlatformConfigurator.kt

@@ -73,7 +73,6 @@ object JvmPlatformConfigurator : PlatformConfiguratorBase(
     ),
 
     additionalAnnotationCheckers = listOf(
-        RepeatableAnnotationChecker,
         FileClassAnnotationsChecker,
         ExplicitMetadataChecker
     ),
@@ -125,5 +124,6 @@ object JvmPlatformConfigurator : PlatformConfiguratorBase(
     override fun configureModuleDependentCheckers(container: StorageComponentContainer) {
         super.configureModuleDependentCheckers(container)
         container.useImpl<ExpectedActualDeclarationChecker>()
+        container.useImpl<RepeatableAnnotationChecker>()
     }
 }