KT-1759 str.plus(str)

compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/Concat.java

@@ -34,12 +34,14 @@ import java.util.List;
 public class Concat implements IntrinsicMethod {
     @Override
     public StackValue generate(ExpressionCodegen codegen, InstructionAdapter v, Type expectedType, PsiElement element, List<JetExpression> arguments, StackValue receiver, @NotNull GenerationState state) {
-        codegen.generateStringBuilderConstructor();
         if (receiver == null || receiver == StackValue.none()) {                                                     // LHS + RHS
+            codegen.generateStringBuilderConstructor();
             codegen.invokeAppend(arguments.get(0));                                // StringBuilder(LHS)
             codegen.invokeAppend(arguments.get(1));
         }
         else {                                    // LHS.plus(RHS)
+            receiver.put(JetTypeMapper.TYPE_OBJECT, v);
+            codegen.generateStringBuilderConstructor();
             v.swap();                                                              // StringBuilder LHS
             codegen.invokeAppendMethod(expectedType);  // StringBuilder(LHS)
             codegen.invokeAppend(arguments.get(0));

compiler/testData/codegen/regressions/kt1759.kt

@@ -0,0 +1,11 @@
+class Greeter(var name : String) {
+    fun greet() {
+        name = name.plus("")
+        System.out?.println("Hello, $name");
+    }
+}
+
+fun box() : String {
+    Greeter("OK").greet()
+    return "OK"
+}

compiler/tests/org/jetbrains/jet/codegen/ClassGenTest.java

@@ -310,7 +310,10 @@ public class ClassGenTest extends CodegenTestCase {
 
     public void testKt1538() throws Exception {
         blackBoxFile("regressions/kt1538.kt");
-        System.out.println(generateToText());
+    }
+
+    public void testKt1759() throws Exception {
+        blackBoxFile("regressions/kt1759.kt");
     }
 
     public void testResolveOrder() throws Exception {