Use FunctionImplN instead of FunctionN in codegen

Superclass of closures should now be FunctionImplN instead of FunctionN. Since
these -Impl classes are needed only in JVM, the corresponding descriptors and
types are created in the back-end only.

compiler/backend/src/org/jetbrains/jet/codegen/CodegenUtil.java

@@ -126,10 +126,10 @@ public class CodegenUtil {
     public static JvmClassName getInternalClassName(FunctionDescriptor descriptor) {
         int paramCount = descriptor.getValueParameters().size();
         if (descriptor.getReceiverParameter() != null) {
-            return JvmClassName.byInternalName("jet/ExtensionFunction" + paramCount);
+            return JvmClassName.byInternalName("jet/ExtensionFunctionImpl" + paramCount);
         }
         else {
-            return JvmClassName.byInternalName("jet/Function" + paramCount);
+            return JvmClassName.byInternalName("jet/FunctionImpl" + paramCount);
         }
     }
 

compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java

@@ -3122,7 +3122,7 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
             v.dup2();
             v.load(indexIndex, Type.INT_TYPE);
             v.invokestatic("java/lang/Integer", "valueOf", "(I)Ljava/lang/Integer;");
-            v.invokevirtual("jet/Function1", "invoke", "(Ljava/lang/Object;)Ljava/lang/Object;");
+            v.invokeinterface("jet/Function1", "invoke", "(Ljava/lang/Object;)Ljava/lang/Object;");
             v.load(indexIndex, Type.INT_TYPE);
             v.iinc(indexIndex, 1);
             v.swap();

compiler/backend/src/org/jetbrains/jet/codegen/binding/CodegenAnnotatingVisitor.java

@@ -22,6 +22,7 @@ import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.descriptors.annotations.AnnotationDescriptor;
 import org.jetbrains.jet.lang.descriptors.impl.ClassDescriptorImpl;
+import org.jetbrains.jet.lang.descriptors.impl.MutableClassDescriptor;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.BindingContext;
 import org.jetbrains.jet.lang.resolve.BindingTrace;
@@ -33,11 +34,10 @@ import org.jetbrains.jet.lang.resolve.java.PackageClassUtils;
 import org.jetbrains.jet.lang.resolve.name.FqName;
 import org.jetbrains.jet.lang.resolve.name.Name;
 import org.jetbrains.jet.lang.resolve.scopes.JetScope;
+import org.jetbrains.jet.lang.types.JetType;
 import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns;
 
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Map;
+import java.util.*;
 
 import static org.jetbrains.jet.codegen.CodegenUtil.peekFromStack;
 import static org.jetbrains.jet.codegen.binding.CodegenBinding.*;
@@ -56,6 +56,42 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
         this.bindingContext = bindingTrace.getBindingContext();
     }
 
+    private static final List<ClassDescriptor> FUNCTIONS;
+    private static final List<ClassDescriptor> EXTENSION_FUNCTIONS;
+
+    static {
+        int n = KotlinBuiltIns.FUNCTION_TRAIT_COUNT;
+        FUNCTIONS = new ArrayList<ClassDescriptor>(n);
+        EXTENSION_FUNCTIONS = new ArrayList<ClassDescriptor>(n);
+
+        KotlinBuiltIns builtIns = KotlinBuiltIns.getInstance();
+        for (int i = 0; i < n; i++) {
+            Name functionImpl = Name.identifier("FunctionImpl" + i);
+            FUNCTIONS.add(createFunctionImplDescriptor(functionImpl, builtIns.getFunction(i)));
+
+            Name extensionFunctionImpl = Name.identifier("ExtensionFunctionImpl" + i);
+            EXTENSION_FUNCTIONS.add(createFunctionImplDescriptor(extensionFunctionImpl, builtIns.getExtensionFunction(i)));
+        }
+    }
+
+    private static ClassDescriptor createFunctionImplDescriptor(Name name, ClassDescriptor functionInterface) {
+        JetScope builtInsScope = KotlinBuiltIns.getInstance().getBuiltInsScope();
+
+        MutableClassDescriptor functionImpl = new MutableClassDescriptor(
+                builtInsScope.getContainingDeclaration(),
+                builtInsScope,
+                ClassKind.CLASS,
+                false,
+                name
+        );
+        functionImpl.setModality(Modality.FINAL);
+        functionImpl.setVisibility(Visibilities.PUBLIC);
+        functionImpl.setTypeParameterDescriptors(functionInterface.getDefaultType().getConstructor().getParameters());
+        functionImpl.createTypeConstructor();
+
+        return functionImpl;
+    }
+
     @Override
     public void visitCallExpression(JetCallExpression expression) {
         super.visitCallExpression(expression);
@@ -92,9 +128,8 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
         ((ClassDescriptorImpl)classDescriptor).initialize(
                 false,
                 Collections.<TypeParameterDescriptor>emptyList(),
-                Collections.singleton((funDescriptor.getReceiverParameter() != null
-                                       ? KotlinBuiltIns.getInstance().getExtensionFunction(arity)
-                                       : KotlinBuiltIns.getInstance().getFunction(arity)).getDefaultType()), JetScope.EMPTY,
+                Collections.singleton(getSuperTypeForClosure(funDescriptor, arity)),
+                JetScope.EMPTY,
                 Collections.<ConstructorDescriptor>emptySet(),
                 null,
                 false);
@@ -104,6 +139,15 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
         return classDescriptor;
     }
 
+    private JetType getSuperTypeForClosure(FunctionDescriptor funDescriptor, int arity) {
+        if (funDescriptor.getReceiverParameter() != null) {
+            return EXTENSION_FUNCTIONS.get(arity).getDefaultType();
+        }
+        else {
+            return FUNCTIONS.get(arity).getDefaultType();
+        }
+    }
+
     private String inventAnonymousClassName(JetElement declaration) {
         String top = peekFromStack(nameStack);
         Integer cnt = anonymousSubclassesCount.get(top);

compiler/frontend/src/org/jetbrains/jet/lang/types/lang/KotlinBuiltIns.java

@@ -80,7 +80,7 @@ public class KotlinBuiltIns {
             BUILT_INS_DIR + "/Unit.jet"
     );
 
-    private static final int FUNCTION_TRAIT_COUNT = 23;
+    public static final int FUNCTION_TRAIT_COUNT = 23;
 
     ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 

compiler/testData/codegen/box/classes/kt1535.kt

@@ -1,9 +1,9 @@
-class Works() : jet.Function0<Object>() {
+class Works() : jet.Function0<Object> {
     public override fun invoke():Object {
       return "Works" as Object
     }
 }
-class Broken() : jet.Function0<String>() {
+class Broken() : jet.Function0<String> {
     public override fun invoke():String {
       return "Broken"
     }

compiler/testData/codegen/box/closures/closureOnTopLevel1.kt

@@ -7,7 +7,7 @@ val getter: String
 
 fun f() = { "OK" }()
 
-val obj = object : Function0<String>() {
+val obj = object : Function0<String> {
     override fun invoke() = "OK"
 }
 

compiler/testData/codegen/box/closures/closureOnTopLevel2.kt

@@ -5,7 +5,7 @@ val getter: String
 
 fun f() = { "OK" }()
 
-val obj = object : Function0<String>() {
+val obj = object : Function0<String> {
     override fun invoke() = "OK"
 }