string plus is an intrinsic

idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java

@@ -35,7 +35,7 @@ import java.util.*;
 public class ExpressionCodegen extends JetVisitor {
     private static final String CLASS_OBJECT = "java/lang/Object";
     private static final String CLASS_STRING = "java/lang/String";
-    private static final String CLASS_STRING_BUILDER = "java/lang/StringBuilder";
+    public static final String CLASS_STRING_BUILDER = "java/lang/StringBuilder";
     private static final String CLASS_COMPARABLE = "java/lang/Comparable";
     private static final String CLASS_ITERABLE = "java/lang/Iterable";
     private static final String CLASS_ITERATOR = "java/util/Iterator";
@@ -1085,11 +1085,6 @@ public class ExpressionCodegen extends JetVisitor {
                                                     Arrays.asList(expression.getLeft(), expression.getRight())));
                     return;
                 }
-                DeclarationDescriptor cls = op.getContainingDeclaration();
-                if (isClass(cls, "String") && op.getName().equals("plus")) {
-                    generateConcatenation(expression);
-                    return;
-                }
             }
             throw new UnsupportedOperationException("Don't know how to generate binary op " + expression);
         }
@@ -1289,15 +1284,7 @@ public class ExpressionCodegen extends JetVisitor {
         }
     }
 
-    private void generateConcatenation(JetBinaryExpression expression) {
+    public void generateStringBuilderConstructor() {
-        generateStringBuilderConstructor();
-        invokeAppend(expression.getLeft());
-        invokeAppend(expression.getRight());
-        v.invokevirtual(CLASS_STRING_BUILDER, "toString", "()Ljava/lang/String;");
-        myStack.push(StackValue.onStack(Type.getObjectType(CLASS_STRING)));
-    }
-
-    private void generateStringBuilderConstructor() {
         Type type = Type.getObjectType(CLASS_STRING_BUILDER);
         v.anew(type);
         v.dup();
@@ -1305,7 +1292,7 @@ public class ExpressionCodegen extends JetVisitor {
         v.invokespecial(CLASS_STRING_BUILDER, method.getName(), method.getDescriptor());
     }
 
-    private void invokeAppend(final JetExpression expr) {
+    public void invokeAppend(final JetExpression expr) {
         if (expr instanceof JetBinaryExpression) {
             final JetBinaryExpression binaryExpression = (JetBinaryExpression) expr;
             if (binaryExpression.getOperationToken() == JetTokens.PLUS) {

idea/src/org/jetbrains/jet/codegen/intrinsics/Concat.java

@@ -0,0 +1,24 @@
+package org.jetbrains.jet.codegen.intrinsics;
+
+import com.intellij.psi.PsiElement;
+import org.jetbrains.jet.codegen.ExpressionCodegen;
+import org.jetbrains.jet.codegen.StackValue;
+import org.jetbrains.jet.lang.psi.JetExpression;
+import org.objectweb.asm.Type;
+import org.objectweb.asm.commons.InstructionAdapter;
+
+import java.util.List;
+
+/**
+ * @author yole
+ */
+public class Concat implements IntrinsicMethod {
+    @Override
+    public StackValue generate(ExpressionCodegen codegen, InstructionAdapter v, Type expectedType, PsiElement element, List<JetExpression> arguments) {
+        codegen.generateStringBuilderConstructor();
+        codegen.invokeAppend(arguments.get(0));
+        codegen.invokeAppend(arguments.get(1));
+        v.invokevirtual(ExpressionCodegen.CLASS_STRING_BUILDER, "toString", "()Ljava/lang/String;");
+        return StackValue.onStack(Type.getObjectType("java/lang/String"));
+    }
+}

idea/src/org/jetbrains/jet/codegen/intrinsics/IntrinsicMethods.java

@@ -19,7 +19,6 @@ import java.util.Map;
 public class IntrinsicMethods {
     private static final IntrinsicMethod UNARY_MINUS = new UnaryMinus();
     private static final IntrinsicMethod NUMBER_CAST = new NumberCast();
-    private static final IntrinsicMethod ARRAY_SIZE = new ArraySize();
     private static final IntrinsicMethod INV = new Inv();
     private static final IntrinsicMethod TYPEINFO = new TypeInfo();
     private static final IntrinsicMethod VALUE_TYPEINFO = new ValueTypeInfo();
@@ -35,7 +34,7 @@ public class IntrinsicMethods {
         for (String method : primitiveCastMethods) {
             declareIntrinsicProperty("Number", method, NUMBER_CAST);
         }
-        declareIntrinsicProperty("Array", "size", ARRAY_SIZE);
+        declareIntrinsicProperty("Array", "size", new ArraySize());
 
         for (String primitiveNumberType : PRIMITIVE_NUMBER_TYPES) {
             declareIntrinsicFunction(primitiveNumberType, "minus", 0, UNARY_MINUS);
@@ -57,6 +56,8 @@ public class IntrinsicMethods {
         declareBinaryOp("and", Opcodes.IAND);
         declareBinaryOp("or", Opcodes.IOR);
         declareBinaryOp("xor", Opcodes.IXOR);
+
+        declareIntrinsicFunction("String", "plus", 1, new Concat());
     }
 
     private void declareBinaryOp(String methodName, int opcode) {