inspection and code cleanup for redundant visibility modifiers

idea/idea-core/src/org/jetbrains/kotlin/idea/core/psiModificationUtils.kt

@@ -166,6 +166,17 @@ public fun KtClass.getOrCreateCompanionObject() : KtObjectDeclaration {
 
 //TODO: code style option whether to insert redundant 'public' keyword or not
 public fun KtDeclaration.setVisibility(visibilityModifier: KtModifierKeywordToken) {
+    val defaultVisibilityKeyword = implicitVisibility()
+
+    if (visibilityModifier == defaultVisibilityKeyword) {
+        this.visibilityModifierType()?.let { removeModifier(it) }
+        return
+    }
+
+    addModifier(visibilityModifier)
+}
+
+fun KtDeclaration.implicitVisibility(): KtModifierKeywordToken? {
     val defaultVisibilityKeyword = if (hasModifier(KtTokens.OVERRIDE_KEYWORD)) {
         (resolveToDescriptor() as? CallableMemberDescriptor)
                 ?.overriddenDescriptors
@@ -175,13 +186,7 @@ public fun KtDeclaration.setVisibility(visibilityModifier: KtModifierKeywordToke
     else {
         KtTokens.DEFAULT_VISIBILITY_KEYWORD
     }
-
-    if (visibilityModifier == defaultVisibilityKeyword) {
-        this.visibilityModifierType()?.let { removeModifier(it) }
-        return
-    }
-
-    addModifier(visibilityModifier)
+    return defaultVisibilityKeyword
 }
 
 fun KtSecondaryConstructor.getOrCreateBody(): KtBlockExpression {

idea/src/META-INF/plugin.xml

@@ -1308,6 +1308,13 @@
                      cleanupTool="true"
                      level="WARNING"/>
 
+    <localInspection implementationClass="org.jetbrains.kotlin.idea.inspections.RedundantVisibilityModifierInspection"
+                     displayName="Redundant visibility modifier"
+                     groupName="Kotlin"
+                     enabledByDefault="true"
+                     cleanupTool="true"
+                     level="WARNING"/>
+
     <referenceImporter implementation="org.jetbrains.kotlin.idea.quickfix.KotlinReferenceImporter"/>
 
     <fileType.fileViewProviderFactory filetype="KJSM" implementationClass="com.intellij.psi.ClassFileViewProviderFactory"/>

idea/src/org/jetbrains/kotlin/idea/inspections/RedundantVisibilityModifierInspection.kt

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.idea.inspections
+
+import com.intellij.codeInspection.*
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiElementVisitor
+import org.jetbrains.kotlin.idea.core.implicitVisibility
+import org.jetbrains.kotlin.psi.KtDeclaration
+import org.jetbrains.kotlin.psi.KtVisitorVoid
+import org.jetbrains.kotlin.psi.psiUtil.visibilityModifier
+
+class RedundantVisibilityModifierInspection : AbstractKotlinInspection(), CleanupLocalInspectionTool {
+    override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean, session: LocalInspectionToolSession): PsiElementVisitor {
+        return object : KtVisitorVoid() {
+            override fun visitDeclaration(dcl: KtDeclaration) {
+                val visibilityModifier = dcl.visibilityModifier() ?: return
+                if (visibilityModifier.node.elementType == dcl.implicitVisibility()) {
+                    holder.registerProblem(visibilityModifier,
+                                           "Redundant visibility modifier",
+                                           ProblemHighlightType.LIKE_UNUSED_SYMBOL,
+                                           RemoveVisibilityModifierFix())
+                }
+            }
+        }
+    }
+
+    class RemoveVisibilityModifierFix : LocalQuickFix {
+        override fun getName(): String = "Remove redundant visibility modifier"
+
+        override fun getFamilyName(): String = getName()
+
+        override fun applyFix(project: Project, descriptor: ProblemDescriptor) {
+            descriptor.psiElement.delete()
+        }
+    }
+}

idea/testData/inspections/redundantVisibilityModifier/inspectionData/expected.xml

@@ -0,0 +1,30 @@
+<problems>
+  <problem>
+    <file>redundantVisibilityModifier.kt</file>
+    <line>1</line>
+    <entry_point TYPE="file" FQNAME="temp:///src/redundantVisibilityModifier.kt" />
+    <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Redundant visibility modifier</problem_class>
+    <description>Redundant visibility modifier</description>
+  </problem>
+  <problem>
+    <file>redundantVisibilityModifier.kt</file>
+    <line>2</line>
+    <entry_point TYPE="file" FQNAME="temp:///src/redundantVisibilityModifier.kt" />
+    <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Redundant visibility modifier</problem_class>
+    <description>Redundant visibility modifier</description>
+  </problem>
+  <problem>
+    <file>redundantVisibilityModifier.kt</file>
+    <line>4</line>
+    <entry_point TYPE="file" FQNAME="temp:///src/redundantVisibilityModifier.kt" />
+    <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Redundant visibility modifier</problem_class>
+    <description>Redundant visibility modifier</description>
+  </problem>
+  <problem>
+    <file>redundantVisibilityModifier.kt</file>
+    <line>17</line>
+    <entry_point TYPE="file" FQNAME="temp:///src/redundantVisibilityModifier.kt" />
+    <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Redundant visibility modifier</problem_class>
+    <description>Redundant visibility modifier</description>
+  </problem>
+</problems>

idea/testData/inspections/redundantVisibilityModifier/inspectionData/inspections.test

@@ -0,0 +1 @@
+// INSPECTION_CLASS: org.jetbrains.kotlin.idea.inspections.RedundantVisibilityModifierInspection

idea/testData/inspections/redundantVisibilityModifier/redundantVisibilityModifier.kt

@@ -0,0 +1,22 @@
+public class C {
+    public val foo: Int = 0
+
+    public fun bar() {}
+
+}
+
+open class D {
+    protected open fun willRemainProtected() {
+    }
+
+    protected open fun willBecomePublic() {
+    }
+}
+
+class E : D() {
+    protected override fun willRemainProtected() {
+    }
+
+    public override fun willBecomePublic() {
+    }
+}

idea/testData/quickfix/redundantVisibilityModifier/.inspection

@@ -0,0 +1 @@
+org.jetbrains.kotlin.idea.inspections.RedundantVisibilityModifierInspection

idea/testData/quickfix/redundantVisibilityModifier/simple.kt

@@ -0,0 +1,3 @@
+// "Remove redundant visibility modifier" "true"
+<caret>public class C {
+}

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

@@ -0,0 +1,3 @@
+// "Remove redundant visibility modifier" "true"
+class C {
+}

idea/tests/org/jetbrains/kotlin/idea/codeInsight/InspectionTestGenerated.java

@@ -118,6 +118,12 @@ public class InspectionTestGenerated extends AbstractInspectionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("redundantVisibilityModifier/inspectionData/inspections.test")
+        public void testRedundantVisibilityModifier_inspectionData_Inspections_test() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspections/redundantVisibilityModifier/inspectionData/inspections.test");
+            doTest(fileName);
+        }
+
         @TestMetadata("spelling/inspectionData/inspections.test")
         public void testSpelling_inspectionData_Inspections_test() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspections/spelling/inspectionData/inspections.test");

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

@@ -5848,6 +5848,21 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
         }
     }
 
+    @TestMetadata("idea/testData/quickfix/redundantVisibilityModifier")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class RedundantVisibilityModifier extends AbstractQuickFixTest {
+        public void testAllFilesPresentInRedundantVisibilityModifier() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/quickfix/redundantVisibilityModifier"), Pattern.compile("^([\\w\\-_]+)\\.kt$"), true);
+        }
+
+        @TestMetadata("simple.kt")
+        public void testSimple() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/redundantVisibilityModifier/simple.kt");
+            doTest(fileName);
+        }
+    }
+
     @TestMetadata("idea/testData/quickfix/removeUnused")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)