Support increment and '+=' on local delegated properties in JS backend

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/DelegatePropertyTest.java

@@ -35,6 +35,14 @@ public class DelegatePropertyTest extends SingleFileTranslationTest {
         checkFooBoxIsOk();
     }
 
+    public void testLocalVarInc() throws Exception {
+        checkFooBoxIsOk();
+    }
+
+    public void testLocalVarPlusAssign() throws Exception {
+        checkFooBoxIsOk();
+    }
+
     public void testCapturedLocalVal() throws Exception {
         checkFooBoxIsOk();
     }

js/js.translator/src/org/jetbrains/kotlin/js/translate/operation/IntrinsicAssignmentTranslator.java

@@ -21,13 +21,14 @@ import com.google.dart.compiler.backend.js.ast.JsBinaryOperator;
 import com.google.dart.compiler.backend.js.ast.JsExpression;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.kotlin.js.translate.context.TranslationContext;
+import org.jetbrains.kotlin.js.translate.utils.TranslationUtils;
 import org.jetbrains.kotlin.lexer.KtToken;
 import org.jetbrains.kotlin.psi.KtBinaryExpression;
-import org.jetbrains.kotlin.psi.KtSimpleNameExpression;
 import org.jetbrains.kotlin.types.expressions.OperatorConventions;
 
 import static org.jetbrains.kotlin.js.translate.utils.PsiUtils.getOperationToken;
 import static org.jetbrains.kotlin.js.translate.utils.PsiUtils.isAssignment;
+import static org.jetbrains.kotlin.js.translate.utils.TranslationUtils.isSimpleNameExpressionNotDelegatedLocalVar;
 
 public final class IntrinsicAssignmentTranslator extends AssignmentTranslator {
 
@@ -53,7 +54,7 @@ public final class IntrinsicAssignmentTranslator extends AssignmentTranslator {
 
     @NotNull
     private JsExpression translateAsAssignmentOperation() {
-        if (expression.getLeft() instanceof KtSimpleNameExpression) {
+        if (isSimpleNameExpressionNotDelegatedLocalVar(expression.getLeft(), context())) {
             return translateAsPlainAssignmentOperation();
         }
         return translateAsAssignToCounterpart();

js/js.translator/src/org/jetbrains/kotlin/js/translate/operation/IntrinsicIncrementTranslator.java

@@ -21,11 +21,11 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.kotlin.js.translate.context.TranslationContext;
 import org.jetbrains.kotlin.lexer.KtToken;
 import org.jetbrains.kotlin.lexer.KtTokens;
-import org.jetbrains.kotlin.psi.KtSimpleNameExpression;
 import org.jetbrains.kotlin.psi.KtUnaryExpression;
 
 import static org.jetbrains.kotlin.js.translate.utils.PsiUtils.getOperationToken;
 import static org.jetbrains.kotlin.js.translate.utils.PsiUtils.isPrefix;
+import static org.jetbrains.kotlin.js.translate.utils.TranslationUtils.isSimpleNameExpressionNotDelegatedLocalVar;
 
 
 public final class IntrinsicIncrementTranslator extends IncrementTranslator {
@@ -44,16 +44,12 @@ public final class IntrinsicIncrementTranslator extends IncrementTranslator {
 
     @NotNull
     private JsExpression translate() {
-        if (isPrimitiveExpressionIncrement()) {
+        if (isSimpleNameExpressionNotDelegatedLocalVar(expression.getBaseExpression(), context())) {
             return primitiveExpressionIncrement();
         }
         return translateIncrementExpression();
     }
 
-    private boolean isPrimitiveExpressionIncrement() {
-        return expression.getBaseExpression() instanceof KtSimpleNameExpression;
-    }
-
     @NotNull
     private JsExpression primitiveExpressionIncrement() {
         JsUnaryOperator operator = OperatorTable.getUnaryOperator(getOperationToken(expression));

js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/TranslationUtils.java

@@ -30,6 +30,7 @@ import org.jetbrains.kotlin.js.translate.context.TemporaryConstVariable;
 import org.jetbrains.kotlin.js.translate.context.TranslationContext;
 import org.jetbrains.kotlin.js.translate.general.Translation;
 import org.jetbrains.kotlin.psi.*;
+import org.jetbrains.kotlin.resolve.BindingContext;
 import org.jetbrains.kotlin.resolve.DescriptorUtils;
 import org.jetbrains.kotlin.types.KotlinType;
 
@@ -295,4 +296,12 @@ public final class TranslationUtils {
         }
         return suggestedName;
     }
+
+    public static boolean isSimpleNameExpressionNotDelegatedLocalVar(@Nullable KtExpression expression, @NotNull TranslationContext context) {
+        if (!(expression instanceof KtSimpleNameExpression)) {
+            return false;
+        }
+        DeclarationDescriptor descriptor = context.bindingContext().get(BindingContext.REFERENCE_TARGET, ((KtSimpleNameExpression) expression));
+        return !(descriptor instanceof LocalVariableDescriptor) || !((LocalVariableDescriptor) descriptor).isDelegated();
+    }
 }

js/js.translator/testData/delegateProperty/cases/localVarInc.kt

@@ -0,0 +1,19 @@
+package foo
+
+import kotlin.reflect.KProperty
+
+class Delegate {
+    var inner = 1
+    operator fun getValue(t: Any?, p: KProperty<*>): Int = inner
+    operator fun setValue(t: Any?, p: KProperty<*>, i: Int) {
+        inner = i
+    }
+}
+
+fun box(): String {
+    var prop: Int by Delegate()
+    var result = prop++
+    if (result != 1) return "fail increment result: $prop"
+    if (prop != 2) return "fail increment: $prop"
+    return "OK"
+}

js/js.translator/testData/delegateProperty/cases/localVarPlusAssign.kt

@@ -0,0 +1,20 @@
+//TODO: reuse same tests from JVM backend
+package foo
+
+import kotlin.reflect.KProperty
+
+class Delegate {
+    var inner = 1
+    operator fun getValue(t: Any?, p: KProperty<*>): Int = inner
+    operator fun setValue(t: Any?, p: KProperty<*>, i: Int) {
+        inner = i
+    }
+}
+
+fun box(): String {
+    var prop: Int by Delegate()
+    prop += 1
+    if (prop != 2) return "fail : $prop"
+    return "OK"
+}
+