toString() for FunctionN classes

It's implemented as if the types were reified: getting the real type parameters
of the corresponding FunctionN class

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

@@ -308,14 +308,15 @@ public class ClosureCodegen extends GenerationStateAware {
             signatureWriter.visitArrayType();
             rawRetType = rawRetType.getElementType();
         }
+
         if (rawRetType.getSort() == Type.OBJECT) {
             signatureWriter.visitClassType(rawRetType.getInternalName());
+            signatureWriter.visitEnd();
         }
         else {
-            // rawRetType is primitive
+            assert isPrimitive(rawRetType);
             signatureWriter.visitBaseType(rawRetType.getDescriptor().charAt(0));
         }
-        signatureWriter.visitEnd();
     }
 
     private static FunctionDescriptor getInvokeFunction(FunctionDescriptor funDescriptor) {

compiler/testData/codegen/box/functions/functionNtoString.kt

@@ -0,0 +1,28 @@
+fun check(expected: String, obj: Any?) {
+    val actual = obj.toString()
+    if (actual != expected)
+        throw AssertionError("Expected: $expected, actual: $actual")
+}
+
+
+fun box(): String {
+    check("jet.FunctionImpl0<jet.Unit>")
+        { () : Unit -> }
+    check("jet.FunctionImpl0<java.lang.Integer>")
+        { () : Int -> 42 }
+    check("jet.FunctionImpl1<java.lang.String, java.lang.Long>")
+        { (s: String) : Long -> 42.toLong() }
+    check("jet.FunctionImpl2<java.lang.Integer, java.lang.Integer, jet.Unit>")
+        { (x: Int, y: Int) : Unit -> }
+
+    check("jet.ExtensionFunctionImpl0<java.lang.Integer, jet.Unit>")
+        { Int.() : Unit -> }
+    check("jet.ExtensionFunctionImpl0<jet.Unit, java.lang.Integer>")
+        { Unit.() : Int -> 42 }
+    check("jet.ExtensionFunctionImpl1<java.lang.String, java.lang.String, java.lang.Long>")
+        { String.(s: String) : Long -> 42.toLong() }
+    check("jet.ExtensionFunctionImpl2<java.lang.Integer, java.lang.Integer, java.lang.Integer, jet.Unit>")
+        { Int.(x: Int, y: Int) : Unit -> }
+
+    return "OK"
+}

compiler/tests/org/jetbrains/jet/codegen/generated/BlackBoxCodegenTestGenerated.java

@@ -1764,6 +1764,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest("compiler/testData/codegen/box/functions/functionExpression.kt");
         }
         
+        @TestMetadata("functionNtoString.kt")
+        public void testFunctionNtoString() throws Exception {
+            doTest("compiler/testData/codegen/box/functions/functionNtoString.kt");
+        }
+        
         @TestMetadata("invoke.kt")
         public void testInvoke() throws Exception {
             doTest("compiler/testData/codegen/box/functions/invoke.kt");