Prevent expression selector from selecting just a label

Previously, extract variable could act on e.g. 'break@outerLoop' and
extract the label, leading into nonsensical 'val x = @outerLoop'.
Prevent JetRefactoringUtil.selectExpression from returning label
expressions to fix this.

 #KT-4515 Fixed

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java

@@ -1042,4 +1042,9 @@ public class JetPsiUtil {
                 expression;
         return (JetToken) elementType;
     }
+
+    public static boolean isLabelIdentifierExpression(PsiElement element) {
+        return element instanceof JetSimpleNameExpression &&
+               ((JetSimpleNameExpression) element).getReferencedNameElementType() == JetTokens.LABEL_IDENTIFIER;
+    }
 }

idea/src/org/jetbrains/jet/plugin/codeInsight/CodeInsightUtils.java

@@ -13,10 +13,7 @@ import com.intellij.refactoring.util.CommonRefactoringUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.FunctionDescriptor;
-import org.jetbrains.jet.lang.psi.JetBlockExpression;
-import org.jetbrains.jet.lang.psi.JetElement;
-import org.jetbrains.jet.lang.psi.JetExpression;
-import org.jetbrains.jet.lang.psi.JetFile;
+import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.types.JetType;
 import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns;
 import org.jetbrains.jet.renderer.DescriptorRenderer;
@@ -35,7 +32,13 @@ public class CodeInsightUtils {
         else if (!(element instanceof JetExpression)) {
             return null;
         }
-        else if (element instanceof JetBlockExpression) {
+
+        // For cases like 'this@outerClass', don't return the label part
+        if (JetPsiUtil.isLabelIdentifierExpression(element)) {
+            element = PsiTreeUtil.getParentOfType(element, JetExpression.class);
+        }
+
+        if (element instanceof JetBlockExpression) {
             List<JetElement> statements = ((JetBlockExpression) element).getStatements();
             if (statements.size() == 1) {
                 JetElement elem = statements.get(0);

idea/src/org/jetbrains/jet/plugin/refactoring/JetRefactoringUtil.java

@@ -405,7 +405,11 @@ public class JetRefactoringUtil {
                && !(element instanceof JetClassBody)) {
             if (element instanceof JetExpression && !(element instanceof JetStatementExpression)) {
                 boolean addExpression = true;
-                if (element.getParent() instanceof JetQualifiedExpression) {
+
+                if (JetPsiUtil.isLabelIdentifierExpression(element)) {
+                    addExpression = false;
+                }
+                else if (element.getParent() instanceof JetQualifiedExpression) {
                     JetQualifiedExpression qualifiedExpression = (JetQualifiedExpression) element.getParent();
                     if (qualifiedExpression.getReceiverExpression() != element) {
                         addExpression = false;

idea/testData/expressionSelection/labelledStatement.kt

@@ -0,0 +1,7 @@
+fun f() {
+    @loop while (true) {
+        break@lo<selection>o</selection>p
+    }
+}
+// KT-4515: Extract variable can attempt to extract a label from a labelled statement.
+/* break@loop */

idea/testData/expressionSelection/labelledThis.kt

@@ -0,0 +1,6 @@
+class Foo() {
+    val s = this@F<selection>o</selection>o.toString()
+}
+
+// KT-4515: Extract variable can attempt to extract a label from a labelled statement.
+/* this@Foo */

idea/testData/smartSelection/labelledStatement.kt

@@ -0,0 +1,7 @@
+fun f() {
+    @loop while (true) {
+        break@lo<caret>op
+    }
+}
+// KT-4515: Extract variable can attempt to extract a label from a labelled statement.
+/* */

idea/tests/org/jetbrains/jet/plugin/ExpressionSelectionTestGenerated.java

@@ -41,6 +41,16 @@ public class ExpressionSelectionTestGenerated extends AbstractExpressionSelectio
         doTestExpressionSelection("idea/testData/expressionSelection/binaryExpr.kt");
     }
     
+    @TestMetadata("labelledStatement.kt")
+    public void testLabelledStatement() throws Exception {
+        doTestExpressionSelection("idea/testData/expressionSelection/labelledStatement.kt");
+    }
+    
+    @TestMetadata("labelledThis.kt")
+    public void testLabelledThis() throws Exception {
+        doTestExpressionSelection("idea/testData/expressionSelection/labelledThis.kt");
+    }
+    
     @TestMetadata("noExpression.kt")
     public void testNoExpression() throws Exception {
         doTestExpressionSelection("idea/testData/expressionSelection/noExpression.kt");

idea/tests/org/jetbrains/jet/plugin/SmartSelectionTestGenerated.java

@@ -36,6 +36,11 @@ public class SmartSelectionTestGenerated extends AbstractSmartSelectionTest {
         JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), "org.jetbrains.jet.generators.tests.TestsPackage", new File("idea/testData/smartSelection"), Pattern.compile("^([^\\.]+)\\.kt$"), true);
     }
     
+    @TestMetadata("labelledStatement.kt")
+    public void testLabelledStatement() throws Exception {
+        doTestSmartSelection("idea/testData/smartSelection/labelledStatement.kt");
+    }
+    
     @TestMetadata("labelledThis.kt")
     public void testLabelledThis() throws Exception {
         doTestSmartSelection("idea/testData/smartSelection/labelledThis.kt");