Add script flag to kotlin.Metadata

This will allow to distinguish compiled scripts from ordinary classes in the
compiler, reflection, IDE, etc.

 #KT-13382 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java

@@ -248,7 +248,7 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
 
     @Override
     protected void generateKotlinMetadataAnnotation() {
-        generateKotlinClassMetadataAnnotation(descriptor);
+        generateKotlinClassMetadataAnnotation(descriptor, false);
     }
 
     private void writeEnclosingMethod() {

compiler/backend/src/org/jetbrains/kotlin/codegen/MemberCodegen.java

@@ -37,6 +37,7 @@ import org.jetbrains.kotlin.fileClasses.FileClasses;
 import org.jetbrains.kotlin.fileClasses.JvmFileClassesProvider;
 import org.jetbrains.kotlin.load.java.JavaVisibilities;
 import org.jetbrains.kotlin.load.java.JvmAbi;
+import org.jetbrains.kotlin.load.java.JvmAnnotationNames;
 import org.jetbrains.kotlin.load.kotlin.header.KotlinClassHeader;
 import org.jetbrains.kotlin.name.Name;
 import org.jetbrains.kotlin.name.SpecialNames;
@@ -86,12 +87,12 @@ public abstract class MemberCodegen<T extends KtPureElement/* TODO: & KtDeclarat
     public final KotlinTypeMapper typeMapper;
     public final BindingContext bindingContext;
 
-    protected final JvmFileClassesProvider fileClassesProvider;
+    private final JvmFileClassesProvider fileClassesProvider;
     private final MemberCodegen<?> parentCodegen;
     private final ReifiedTypeParametersUsages reifiedTypeParametersUsages = new ReifiedTypeParametersUsages();
     private final Collection<ClassDescriptor> innerClasses = new LinkedHashSet<ClassDescriptor>();
 
-    protected ExpressionCodegen clInit;
+    private ExpressionCodegen clInit;
     private NameGenerator inlineNameGenerator;
 
     private DefaultSourceMapper sourceMapper;
@@ -439,7 +440,7 @@ public abstract class MemberCodegen<T extends KtPureElement/* TODO: & KtDeclarat
     }
 
     @NotNull
-    protected SimpleFunctionDescriptorImpl createClInitFunctionDescriptor(@NotNull DeclarationDescriptor descriptor) {
+    private SimpleFunctionDescriptorImpl createClInitFunctionDescriptor(@NotNull DeclarationDescriptor descriptor) {
         SimpleFunctionDescriptorImpl clInit = SimpleFunctionDescriptorImpl.create(descriptor, Annotations.Companion.getEMPTY(),
                 Name.special("<clinit>"), SYNTHESIZED, KotlinSourceElementKt.toSourceElement(element));
         clInit.initialize(null, null, Collections.<TypeParameterDescriptor>emptyList(),
@@ -698,7 +699,7 @@ public abstract class MemberCodegen<T extends KtPureElement/* TODO: & KtDeclarat
 
             class PropertyAccessorStrategy extends FunctionGenerationStrategy.CodegenBased {
                 private final PropertyAccessorDescriptor callableDescriptor;
-                public PropertyAccessorStrategy(@NotNull PropertyAccessorDescriptor callableDescriptor) {
+                private PropertyAccessorStrategy(@NotNull PropertyAccessorDescriptor callableDescriptor) {
                     super(MemberCodegen.this.state);
                     this.callableDescriptor = callableDescriptor;
                 }
@@ -799,13 +800,15 @@ public abstract class MemberCodegen<T extends KtPureElement/* TODO: & KtDeclarat
         return StackValue.onStack(callableMethod.getReturnType());
     }
 
-    protected void generateKotlinClassMetadataAnnotation(ClassDescriptor descriptor) {
+    protected void generateKotlinClassMetadataAnnotation(@NotNull ClassDescriptor descriptor, boolean isScript) {
         final DescriptorSerializer serializer =
                 DescriptorSerializer.create(descriptor, new JvmSerializerExtension(v.getSerializationBindings(), state));
 
         final ProtoBuf.Class classProto = serializer.classProto(descriptor).build();
 
-        WriteAnnotationUtilKt.writeKotlinMetadata(v, state, KotlinClassHeader.Kind.CLASS, 0, new Function1<AnnotationVisitor, Unit>() {
+        int flags = isScript ? JvmAnnotationNames.METADATA_SCRIPT_FLAG : 0;
+
+        WriteAnnotationUtilKt.writeKotlinMetadata(v, state, KotlinClassHeader.Kind.CLASS, flags, new Function1<AnnotationVisitor, Unit>() {
             @Override
             public Unit invoke(AnnotationVisitor av) {
                 writeAnnotationData(av, serializer, classProto);

compiler/backend/src/org/jetbrains/kotlin/codegen/ScriptCodegen.java

@@ -22,7 +22,10 @@ import org.jetbrains.kotlin.codegen.context.CodegenContext;
 import org.jetbrains.kotlin.codegen.context.MethodContext;
 import org.jetbrains.kotlin.codegen.context.ScriptContext;
 import org.jetbrains.kotlin.codegen.state.GenerationState;
-import org.jetbrains.kotlin.descriptors.*;
+import org.jetbrains.kotlin.descriptors.ClassDescriptor;
+import org.jetbrains.kotlin.descriptors.ConstructorDescriptor;
+import org.jetbrains.kotlin.descriptors.ScriptDescriptor;
+import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor;
 import org.jetbrains.kotlin.psi.*;
 import org.jetbrains.kotlin.resolve.BindingContext;
 import org.jetbrains.kotlin.resolve.descriptorUtil.DescriptorUtilsKt;
@@ -33,7 +36,6 @@ import org.jetbrains.org.objectweb.asm.MethodVisitor;
 import org.jetbrains.org.objectweb.asm.Type;
 import org.jetbrains.org.objectweb.asm.commons.InstructionAdapter;
 
-import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
@@ -110,8 +112,7 @@ public class ScriptCodegen extends MemberCodegen<KtScript> {
 
     @Override
     protected void generateKotlinMetadataAnnotation() {
-        // TODO: copypaste from ImplementationBodyCodegen, so the script is seen as a KClass by reflection; implement separate kind with proper API
-        generateKotlinClassMetadataAnnotation(scriptDescriptor);
+        generateKotlinClassMetadataAnnotation(scriptDescriptor, true);
     }
 
     private void genConstructor(

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

@@ -36,6 +36,7 @@ public final class JvmAnnotationNames {
 
     public static final int METADATA_MULTIFILE_PARTS_INHERIT_FLAG = 1 << 0;
     public static final int METADATA_PRE_RELEASE_FLAG = 1 << 1;
+    public static final int METADATA_SCRIPT_FLAG = 1 << 2;
 
     public static final Name DEFAULT_ANNOTATION_MEMBER_NAME = Name.identifier("value");
 

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/kotlin/header/KotlinClassHeader.kt

@@ -71,5 +71,8 @@ class KotlinClassHeader(
     val isPreRelease: Boolean
         get() = (extraInt and JvmAnnotationNames.METADATA_PRE_RELEASE_FLAG) != 0
 
+    val isScript: Boolean
+        get() = (extraInt and JvmAnnotationNames.METADATA_SCRIPT_FLAG) != 0
+
     override fun toString() = "$kind version=$metadataVersion"
 }

core/runtime.jvm/src/kotlin/Metadata.kt

@@ -61,6 +61,7 @@ internal annotation class Metadata(
          *
          * 0 - this is a multi-file class facade or part, compiled with `-Xmultifile-parts-inherit`.
          * 1 - this class file is compiled by a pre-release version of Kotlin and is not visible to release versions.
+         * 2 - this class file is a compiled Kotlin script source file (.kts).
          */
         val xi: Int = 0
 )