Add "Remove redundant label" quick fix for REDUNDANT_LABEL_WARNING

#KT-26431 Fixed

idea/src/org/jetbrains/kotlin/idea/quickfix/QuickFixRegistrar.kt

@@ -613,5 +613,7 @@ class QuickFixRegistrar : QuickFixContributor {
         NO_VALUE_FOR_PARAMETER.registerFactory(AddConstructorParameterFromSuperTypeCallFix)
 
         UNEXPECTED_TRAILING_LAMBDA_ON_A_NEW_LINE.registerFactory(AddSemicolonBeforeLambdaExpressionFix.Factory)
+
+        REDUNDANT_LABEL_WARNING.registerFactory(RemoveRedundantLabelFix)
     }
 }

idea/src/org/jetbrains/kotlin/idea/quickfix/RemoveRedundantLabelFix.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.idea.quickfix
+
+import com.intellij.openapi.editor.Editor
+import com.intellij.openapi.project.Project
+import org.jetbrains.kotlin.diagnostics.Diagnostic
+import org.jetbrains.kotlin.psi.KtFile
+import org.jetbrains.kotlin.psi.KtLabelReferenceExpression
+import org.jetbrains.kotlin.psi.KtLabeledExpression
+import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
+
+class RemoveRedundantLabelFix(element: KtLabeledExpression) : KotlinQuickFixAction<KtLabeledExpression>(element) {
+    override fun getText(): String = "Remove redundant label"
+
+    override fun getFamilyName(): String = text
+
+    override fun invoke(project: Project, editor: Editor?, file: KtFile) {
+        val labeledExpression = element ?: return
+        val baseExpression = labeledExpression.baseExpression ?: return
+        labeledExpression.replace(baseExpression)
+    }
+
+    companion object : KotlinSingleIntentionActionFactory() {
+        override fun createAction(diagnostic: Diagnostic): KotlinQuickFixAction<KtLabeledExpression>? {
+            val labelReference = diagnostic.psiElement as? KtLabelReferenceExpression ?: return null
+            val labeledExpression = labelReference.getStrictParentOfType<KtLabeledExpression>() ?: return null
+            return RemoveRedundantLabelFix(labeledExpression)
+        }
+    }
+}

idea/testData/quickfix/removeRedundantLabel/simple.kt

@@ -0,0 +1,6 @@
+// "Remove redundant label" "true"
+fun foo() {
+    <caret>L1@ val x = L2@ bar()
+}
+
+fun bar() {}

idea/testData/quickfix/removeRedundantLabel/simple.kt.after

@@ -0,0 +1,6 @@
+// "Remove redundant label" "true"
+fun foo() {
+    val x = L2@ bar()
+}
+
+fun bar() {}

idea/testData/quickfix/removeRedundantLabel/simple2.kt

@@ -0,0 +1,6 @@
+// "Remove redundant label" "true"
+fun foo() {
+    L1@ val x = L2@<caret> bar()
+}
+
+fun bar() {}

idea/testData/quickfix/removeRedundantLabel/simple2.kt.after

@@ -0,0 +1,6 @@
+// "Remove redundant label" "true"
+fun foo() {
+    L1@ val x = bar()
+}
+
+fun bar() {}

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixMultiFileTestGenerated.java

@@ -3673,6 +3673,19 @@ public class QuickFixMultiFileTestGenerated extends AbstractQuickFixMultiFileTes
         }
     }
 
+    @TestMetadata("idea/testData/quickfix/removeRedundantLabel")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class RemoveRedundantLabel extends AbstractQuickFixMultiFileTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTestWithExtraFile, TargetBackend.ANY, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInRemoveRedundantLabel() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/quickfix/removeRedundantLabel"), Pattern.compile("^(\\w+)\\.((before\\.Main\\.\\w+)|(test))$"), TargetBackend.ANY, true);
+        }
+    }
+
     @TestMetadata("idea/testData/quickfix/removeSingleLambdaParameter")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixTestGenerated.java

@@ -10303,6 +10303,29 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
         }
     }
 
+    @TestMetadata("idea/testData/quickfix/removeRedundantLabel")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class RemoveRedundantLabel extends AbstractQuickFixTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, TargetBackend.ANY, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInRemoveRedundantLabel() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/quickfix/removeRedundantLabel"), Pattern.compile("^([\\w\\-_]+)\\.kt$"), TargetBackend.ANY, true);
+        }
+
+        @TestMetadata("simple.kt")
+        public void testSimple() throws Exception {
+            runTest("idea/testData/quickfix/removeRedundantLabel/simple.kt");
+        }
+
+        @TestMetadata("simple2.kt")
+        public void testSimple2() throws Exception {
+            runTest("idea/testData/quickfix/removeRedundantLabel/simple2.kt");
+        }
+    }
+
     @TestMetadata("idea/testData/quickfix/removeSingleLambdaParameter")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)