Write KotlinSyntheticClass annotation on when-by-enum mapping classes

compiler/backend/src/org/jetbrains/kotlin/codegen/when/MappingClassesForWhenByEnumCodegen.java

@@ -30,6 +30,8 @@ import org.jetbrains.org.objectweb.asm.commons.InstructionAdapter;
 import java.util.List;
 import java.util.Map;
 
+import static org.jetbrains.kotlin.codegen.AsmUtil.writeKotlinSyntheticClassAnnotation;
+import static org.jetbrains.kotlin.load.java.JvmAnnotationNames.KotlinSyntheticClass.Kind.WHEN_ON_ENUM_MAPPINGS;
 import static org.jetbrains.kotlin.resolve.jvm.AsmTypes.OBJECT_TYPE;
 import static org.jetbrains.org.objectweb.asm.Opcodes.*;
 
@@ -56,6 +58,8 @@ public class MappingClassesForWhenByEnumCodegen {
         generateFields(cb, mappings);
         generateInitialization(cb, mappings);
 
+        writeKotlinSyntheticClassAnnotation(cb, WHEN_ON_ENUM_MAPPINGS);
+
         cb.done();
     }
 

compiler/tests/org/jetbrains/kotlin/codegen/KotlinSyntheticClassAnnotationTest.java

@@ -143,6 +143,15 @@ public class KotlinSyntheticClassAnnotationTest extends CodegenTestCase {
         );
     }
 
+    public void testWhenMappings() {
+        doTestKotlinSyntheticClass(
+                "enum class E { A }\n" +
+                "val x = when (E.A) { E.A -> 1; else -> 0; }",
+                "WhenMappings",
+                WHEN_ON_ENUM_MAPPINGS
+        );
+    }
+
     private void doTestKotlinSyntheticClass(
             @NotNull String code,
             @NotNull String classFilePart,

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/JvmAnnotationNames.java

@@ -78,6 +78,7 @@ public final class JvmAnnotationNames {
             CALLABLE_REFERENCE_WRAPPER,
             LOCAL_FUNCTION,
             ANONYMOUS_FUNCTION,
+            WHEN_ON_ENUM_MAPPINGS,
             ;
         }
     }

core/runtime.jvm/src/kotlin/jvm/internal/KotlinSyntheticClass.java

@@ -34,5 +34,6 @@ public @interface KotlinSyntheticClass {
         CALLABLE_REFERENCE_WRAPPER,
         LOCAL_FUNCTION,
         ANONYMOUS_FUNCTION,
+        WHEN_ON_ENUM_MAPPINGS,
     }
 }