"add operator modifier" fix handles fake overrides

#KT-9347 Fixed

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

@@ -28,17 +28,20 @@ import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.diagnostics.Diagnostic
 import org.jetbrains.kotlin.diagnostics.DiagnosticWithParameters2
+import org.jetbrains.kotlin.idea.codeInsight.DescriptorToSourceUtilsIde
 import org.jetbrains.kotlin.idea.quickfix.AddModifierFix
 import org.jetbrains.kotlin.idea.quickfix.CleanupFix
 import org.jetbrains.kotlin.idea.quickfix.JetSingleIntentionActionFactory
 import org.jetbrains.kotlin.idea.search.usagesSearch.descriptor
 import org.jetbrains.kotlin.lexer.JetTokens
-import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.JetClassOrObject
+import org.jetbrains.kotlin.psi.JetModifierListOwner
+import org.jetbrains.kotlin.psi.JetNamedFunction
+import org.jetbrains.kotlin.psi.JetVisitorVoid
 import org.jetbrains.kotlin.psi.psiUtil.getNonStrictParentOfType
 import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
 import org.jetbrains.kotlin.resolve.OverrideResolver
 import org.jetbrains.kotlin.resolve.dataClassUtils.isComponentLike
-import org.jetbrains.kotlin.resolve.source.PsiSourceElement
 import org.jetbrains.kotlin.types.expressions.OperatorConventions
 
 public class OperatorModifierInspection : AbstractKotlinInspection() {
@@ -122,8 +125,9 @@ private class AddModifierLocalQuickFix() : LocalQuickFix {
 
 object OperatorModifierFixFactory : JetSingleIntentionActionFactory() {
     override fun createAction(diagnostic: Diagnostic): IntentionAction? {
-        val param = (diagnostic as? DiagnosticWithParameters2<*, *, *>)?.a as? FunctionDescriptor ?: return null
-        val target = (param.source as? PsiSourceElement)?.psi as? JetDeclaration ?: return null
+        val functionDescriptor = (diagnostic as? DiagnosticWithParameters2<*, *, *>)?.a as? FunctionDescriptor ?: return null
+        val target = DescriptorToSourceUtilsIde.getAnyDeclaration(diagnostic.psiFile.project, functionDescriptor)
+                as? JetModifierListOwner ?: return null
         return object : AddModifierFix(target, JetTokens.OPERATOR_KEYWORD), CleanupFix {}
     }
 }

idea/testData/quickfix/modifiers/operatorModifierInherited.kt

@@ -0,0 +1,10 @@
+// "Add 'operator' modifier" "true"
+open class Foo {
+    fun get(idx: Int): Any = 5
+}
+
+object Bar : Foo()
+
+fun test(): Any {
+    return Bar<caret>[5]
+}

idea/testData/quickfix/modifiers/operatorModifierInherited.kt.after

@@ -0,0 +1,10 @@
+// "Add 'operator' modifier" "true"
+open class Foo {
+    operator fun get(idx: Int): Any = 5
+}
+
+object Bar : Foo()
+
+fun test(): Any {
+    return Bar<caret>[5]
+}

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

@@ -4427,6 +4427,12 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
             doTest(fileName);
         }
 
+        @TestMetadata("operatorModifierInherited.kt")
+        public void testOperatorModifierInherited() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/quickfix/modifiers/operatorModifierInherited.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("packageMemberCannotBeProtected.kt")
         public void testPackageMemberCannotBeProtected() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("idea/testData/quickfix/modifiers/packageMemberCannotBeProtected.kt");