invokeinterface FunctionN.invoke()

Instead of invokevirtual on FunctionImpl class, do invokeinterface on a
Function trait. This will allow to invoke functions on classes which don't
inherit from FunctionImpl classes.

Also rename the method to the more sensible name

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

@@ -1975,7 +1975,7 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
     @NotNull
     private CallableMethod resolveToCallableMethod(@NotNull FunctionDescriptor fd, boolean superCall, @NotNull CodegenContext context) {
         if (isCallAsFunctionObject(fd)) {
-            return typeMapper.asCallableMethod(createInvoke(fd));
+            return typeMapper.mapToFunctionInvokeCallableMethod(createInvoke(fd));
         }
         else {
             SimpleFunctionDescriptor originalOfSamAdapter = getOriginalIfSamAdapter(fd);

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

@@ -80,6 +80,17 @@ public class FunctionTypesUtil {
         return functionImpl;
     }
 
+    @NotNull
+    public static JvmClassName getFunctionTraitClassName(@NotNull FunctionDescriptor descriptor) {
+        int paramCount = descriptor.getValueParameters().size();
+        if (descriptor.getReceiverParameter() != null) {
+            return JvmClassName.byInternalName("jet/ExtensionFunction" + paramCount);
+        }
+        else {
+            return JvmClassName.byInternalName("jet/Function" + paramCount);
+        }
+    }
+
     @NotNull
     public static JvmClassName getFunctionImplClassName(@NotNull FunctionDescriptor descriptor) {
         int paramCount = descriptor.getValueParameters().size();

compiler/backend/src/org/jetbrains/jet/codegen/state/JetTypeMapper.java

@@ -47,7 +47,7 @@ import static org.jetbrains.asm4.Opcodes.*;
 import static org.jetbrains.jet.codegen.AsmUtil.boxType;
 import static org.jetbrains.jet.codegen.AsmUtil.getTraitImplThisParameterType;
 import static org.jetbrains.jet.codegen.CodegenUtil.*;
-import static org.jetbrains.jet.codegen.FunctionTypesUtil.getFunctionImplClassName;
+import static org.jetbrains.jet.codegen.FunctionTypesUtil.getFunctionTraitClassName;
 import static org.jetbrains.jet.codegen.binding.CodegenBinding.*;
 
 public class JetTypeMapper extends BindingTraceAware {
@@ -936,9 +936,10 @@ public class JetTypeMapper extends BindingTraceAware {
         return null;
     }
 
-    public CallableMethod asCallableMethod(FunctionDescriptor fd) {
+    @NotNull
+    public CallableMethod mapToFunctionInvokeCallableMethod(@NotNull FunctionDescriptor fd) {
         JvmMethodSignature descriptor = erasedInvokeSignature(fd);
-        JvmClassName owner = getFunctionImplClassName(fd);
+        JvmClassName owner = getFunctionTraitClassName(fd);
         Type receiverParameterType;
         ReceiverParameterDescriptor receiverParameter = fd.getOriginal().getReceiverParameter();
         if (receiverParameter != null) {
@@ -947,6 +948,6 @@ public class JetTypeMapper extends BindingTraceAware {
         else {
             receiverParameterType = null;
         }
-        return new CallableMethod(owner, null, null, descriptor, INVOKEVIRTUAL, owner, receiverParameterType, owner.getAsmType());
+        return new CallableMethod(owner, null, null, descriptor, INVOKEINTERFACE, owner, receiverParameterType, owner.getAsmType());
     }
 }