Added fake override search in unused symbol inspection #KT-13288 Fixed

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

@@ -29,6 +29,7 @@ import com.intellij.codeInspection.ex.EntryPointsManagerBase
 import com.intellij.codeInspection.ex.EntryPointsManagerImpl
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.util.text.StringUtil
+import com.intellij.psi.PsiClass
 import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiElementVisitor
 import com.intellij.psi.PsiReference
@@ -40,11 +41,16 @@ import com.intellij.psi.search.searches.DefinitionsScopedSearch
 import com.intellij.psi.search.searches.ReferencesSearch
 import com.intellij.refactoring.safeDelete.SafeDeleteHandler
 import org.jetbrains.kotlin.asJava.LightClassUtil
+import org.jetbrains.kotlin.asJava.classes.KtLightClass
 import org.jetbrains.kotlin.asJava.toLightClass
 import org.jetbrains.kotlin.asJava.toLightMethods
+import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.annotations.Annotated
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.idea.caches.resolve.resolveToDescriptorIfAny
+import org.jetbrains.kotlin.idea.core.toDescriptor
 import org.jetbrains.kotlin.idea.findUsages.KotlinFindUsagesHandlerFactory
 import org.jetbrains.kotlin.idea.findUsages.handlers.KotlinFindClassUsagesHandler
 import org.jetbrains.kotlin.idea.imports.importableFqName
@@ -57,6 +63,7 @@ import org.jetbrains.kotlin.psi.psiUtil.*
 import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
 import org.jetbrains.kotlin.util.OperatorNameConventions
+import org.jetbrains.kotlin.util.findCallableMemberBySignature
 import org.jetbrains.kotlin.utils.singletonOrEmptyList
 import java.awt.GridBagConstraints
 import java.awt.GridBagLayout
@@ -154,7 +161,7 @@ class UnusedSymbolInspection : AbstractKotlinInspection() {
                 if (declaration is KtNamedFunction && isConventionalName(declaration)) return
 
                 // More expensive, resolve-based checks
-                if (declaration.resolveToDescriptorIfAny() == null) return
+                declaration.resolveToDescriptorIfAny() ?: return
                 if (isEntryPoint(declaration)) return
                 if (declaration is KtProperty && declaration.isSerializationImplicitlyUsedField()) return
                 if (declaration is KtNamedFunction && declaration.isSerializationImplicitlyUsedMethod()) return
@@ -232,8 +239,8 @@ class UnusedSymbolInspection : AbstractKotlinInspection() {
         return (declaration is KtObjectDeclaration && declaration.isCompanion() &&
                 declaration.getBody()?.declarations?.isNotEmpty() == true) ||
                hasReferences(declaration, useScope) ||
-               hasOverrides(declaration, useScope)
+               hasOverrides(declaration, useScope) ||
-
+               hasFakeOverrides(declaration, useScope)
     }
 
     private fun hasReferences(declaration: KtNamedDeclaration, useScope: SearchScope): Boolean {
@@ -272,6 +279,37 @@ class UnusedSymbolInspection : AbstractKotlinInspection() {
         return DefinitionsScopedSearch.search(declaration, useScope).findFirst() != null
     }
 
+    private fun hasFakeOverrides(declaration: KtNamedDeclaration, useScope: SearchScope): Boolean {
+        val ownerClass = declaration.containingClassOrObject as? KtClass ?: return false
+        if (!ownerClass.isInheritable()) return false
+        val descriptor = declaration.toDescriptor() as? CallableMemberDescriptor ?: return false
+        if (descriptor.modality == Modality.ABSTRACT) return false
+        val lightMethods = declaration.toLightMethods()
+        return DefinitionsScopedSearch.search(ownerClass, useScope).any {
+            element: PsiElement ->
+
+            when (element) {
+                is KtLightClass -> {
+                    val memberBySignature =
+                            (element.kotlinOrigin?.toDescriptor() as? ClassDescriptor)?.findCallableMemberBySignature(descriptor)
+                    memberBySignature != null &&
+                    !memberBySignature.kind.isReal &&
+                    memberBySignature.overriddenDescriptors.any { it != descriptor }
+                }
+                is PsiClass ->
+                    lightMethods.any {
+                        lightMethod ->
+
+                        val sameMethods = element.findMethodsBySignature(lightMethod, true)
+                        sameMethods.all { it.containingClass != element } &&
+                        sameMethods.any { it.containingClass != lightMethod.containingClass }
+                    }
+                else ->
+                    false
+            }
+        }
+    }
+
     override fun createOptionsPanel(): JComponent? {
         val panel = JPanel(GridBagLayout())
         panel.add(

idea/testData/inspections/unusedSymbol/property/triangle.kt

@@ -0,0 +1,17 @@
+// See KT-13288
+
+interface Inter {
+    fun something(): String
+}
+
+abstract class Abstract {
+    fun something() = "hi"
+}
+
+class Test: Abstract(), Inter {
+}
+
+fun main(args: Array<String>) {
+    val x: Inter = Test()
+    x.something()
+}

idea/testData/quickfix/removeUnused/deledage.kt

@@ -0,0 +1,15 @@
+// "Safe delete 'something'" "false"
+// ACTION: Convert function to property
+// ACTION: Convert to block body
+// ACTION: Specify return type explicitly
+
+interface Inter {
+    fun something(): String
+}
+
+class Impl : Inter {
+    override fun <caret>something() = "hi"
+}
+
+class Test: Inter by Impl() {
+}

idea/testData/quickfix/removeUnused/javaTriangle.before.Dependency.java

@@ -0,0 +1,3 @@
+interface Inter {
+    String something();
+}

idea/testData/quickfix/removeUnused/javaTriangle.before.Main.kt

@@ -0,0 +1,13 @@
+// "Safe delete 'something'" "false"
+// ACTION: Convert function to property
+// ACTION: Convert member to extension
+// ACTION: Convert to block body
+// ACTION: Move to companion object
+// ACTION: Specify return type explicitly
+
+abstract class Abstract {
+    fun <caret>something() = "hi"
+}
+
+class Test: Abstract(), Inter {
+}

idea/testData/quickfix/removeUnused/javaTriangle2.before.Dependency.java

@@ -0,0 +1,7 @@
+interface Inter {
+    String something();
+}
+
+class Test extends Abstract implements Inter {
+
+}

idea/testData/quickfix/removeUnused/javaTriangle2.before.Main.kt

@@ -0,0 +1,10 @@
+// "Safe delete 'something'" "false"
+// ACTION: Convert function to property
+// ACTION: Convert member to extension
+// ACTION: Convert to block body
+// ACTION: Move to companion object
+// ACTION: Specify return type explicitly
+
+abstract class Abstract {
+    fun <caret>something() = "hi"
+}

idea/testData/quickfix/removeUnused/javaTriangle3.before.Dependency.java

@@ -0,0 +1,5 @@
+class Test extends Abstract {
+    String something() {
+        return "123";
+    }
+}

idea/testData/quickfix/removeUnused/javaTriangle3.before.Main.kt

@@ -0,0 +1,11 @@
+// "Safe delete 'something'" "false"
+// ACTION: Convert function to property
+// ACTION: Convert member to extension
+// ACTION: Convert to block body
+// ACTION: Move to companion object
+// ACTION: Specify return type explicitly
+
+
+abstract class Abstract {
+    open fun <caret>something() = "hi"
+}

idea/testData/quickfix/removeUnused/javaTriangleUnused.after.kt

@@ -0,0 +1,4 @@
+// "Safe delete 'something'" "true"
+
+abstract class Abstract {
+}

idea/testData/quickfix/removeUnused/javaTriangleUnused.before.Dependency.java

@@ -0,0 +1,9 @@
+interface Inter {
+    String something();
+}
+
+class Test extends Abstract implements Inter {
+    String something() {
+        return "123";
+    }
+}

idea/testData/quickfix/removeUnused/javaTriangleUnused.before.Main.kt

@@ -0,0 +1,5 @@
+// "Safe delete 'something'" "true"
+
+abstract class Abstract {
+    fun <caret>something() = "hi"
+}

idea/testData/quickfix/removeUnused/javaTriangleUnused2.after.kt

@@ -0,0 +1,4 @@
+// "Safe delete 'something'" "true"
+
+abstract class Abstract {
+}

idea/testData/quickfix/removeUnused/javaTriangleUnused2.before.Dependency.java

@@ -0,0 +1,2 @@
+class Test extends Abstract {
+}

idea/testData/quickfix/removeUnused/javaTriangleUnused2.before.Main.kt

@@ -0,0 +1,5 @@
+// "Safe delete 'something'" "true"
+
+abstract class Abstract {
+    fun <caret>something() = "hi"
+}

idea/testData/quickfix/removeUnused/notTriangle.kt

@@ -0,0 +1,8 @@
+// "Safe delete 'something'" "true"
+
+abstract class Abstract {
+    open fun <caret>something() = "hi"
+}
+
+class Test: Abstract() {
+}

idea/testData/quickfix/removeUnused/notTriangle.kt.after

@@ -0,0 +1,7 @@
+// "Safe delete 'something'" "true"
+
+abstract class Abstract {
+}
+
+class Test: Abstract() {
+}

idea/testData/quickfix/removeUnused/triangle.kt

@@ -0,0 +1,17 @@
+// "Safe delete 'something'" "false"
+// ACTION: Convert function to property
+// ACTION: Convert member to extension
+// ACTION: Convert to block body
+// ACTION: Move to companion object
+// ACTION: Specify return type explicitly
+
+interface Inter {
+    fun something(): String
+}
+
+abstract class Abstract {
+    fun <caret>something() = "hi"
+}
+
+class Test: Abstract(), Inter {
+}

idea/testData/quickfix/removeUnused/triangle2.kt

@@ -0,0 +1,18 @@
+// "Safe delete 'something'" "false"
+// ACTION: Convert function to property
+// ACTION: Convert member to extension
+// ACTION: Convert to block body
+// ACTION: Move to companion object
+// ACTION: Specify return type explicitly
+
+interface Inter {
+    fun something(): String
+}
+
+abstract class Abstract {
+    open fun <caret>something() = "hi"
+}
+
+class Test: Abstract(), Inter {
+    override fun something() = "bye"
+}

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

@@ -1537,6 +1537,36 @@ public class QuickFixMultiFileTestGenerated extends AbstractQuickFixMultiFileTes
             KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/quickfix/removeUnused"), Pattern.compile("^(\\w+)\\.((before\\.Main\\.\\w+)|(test))$"), true);
         }
 
+        @TestMetadata("javaTriangle.before.Main.kt")
+        public void testJavaTriangle() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/removeUnused/javaTriangle.before.Main.kt");
+            doTestWithExtraFile(fileName);
+        }
+
+        @TestMetadata("javaTriangle2.before.Main.kt")
+        public void testJavaTriangle2() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/removeUnused/javaTriangle2.before.Main.kt");
+            doTestWithExtraFile(fileName);
+        }
+
+        @TestMetadata("javaTriangle3.before.Main.kt")
+        public void testJavaTriangle3() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/removeUnused/javaTriangle3.before.Main.kt");
+            doTestWithExtraFile(fileName);
+        }
+
+        @TestMetadata("javaTriangleUnused.before.Main.kt")
+        public void testJavaTriangleUnused() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/removeUnused/javaTriangleUnused.before.Main.kt");
+            doTestWithExtraFile(fileName);
+        }
+
+        @TestMetadata("javaTriangleUnused2.before.Main.kt")
+        public void testJavaTriangleUnused2() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/removeUnused/javaTriangleUnused2.before.Main.kt");
+            doTestWithExtraFile(fileName);
+        }
+
         @TestMetadata("usedObjectAsAliasMulti.before.Main.kt")
         public void testUsedObjectAsAliasMulti() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/removeUnused/usedObjectAsAliasMulti.before.Main.kt");

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

@@ -6901,6 +6901,30 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
             KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/quickfix/removeUnused"), Pattern.compile("^([\\w\\-_]+)\\.kt$"), true);
         }
 
+        @TestMetadata("deledage.kt")
+        public void testDeledage() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/removeUnused/deledage.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("notTriangle.kt")
+        public void testNotTriangle() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/removeUnused/notTriangle.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("triangle.kt")
+        public void testTriangle() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/removeUnused/triangle.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("triangle2.kt")
+        public void testTriangle2() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/removeUnused/triangle2.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("unusedClass.kt")
         public void testUnusedClass() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/removeUnused/unusedClass.kt");