Fix several false positives and make safer "redundant companion ref"

Don't report it on an import directive #KT-23520 Fixed
Don't report it if companion nested class is referenced #KT-23519 Fixed
Check companion reference both by descriptor and by name

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

@@ -11,24 +11,28 @@ import com.intellij.codeInspection.ProblemHighlightType
 import com.intellij.codeInspection.ProblemsHolder
 import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiElementVisitor
+import org.jetbrains.kotlin.descriptors.ConstructorDescriptor
+import org.jetbrains.kotlin.idea.caches.resolve.resolveToCall
 import org.jetbrains.kotlin.idea.references.mainReference
-import org.jetbrains.kotlin.idea.search.usagesSearch.descriptor
+import org.jetbrains.kotlin.psi.*
-import org.jetbrains.kotlin.psi.KtDotQualifiedExpression
+import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
-import org.jetbrains.kotlin.psi.KtObjectDeclaration
-import org.jetbrains.kotlin.psi.KtReferenceExpression
-import org.jetbrains.kotlin.psi.referenceExpressionVisitor
-import org.jetbrains.kotlin.resolve.DescriptorUtils
 
 class RedundantCompanionReferenceInspection : AbstractKotlinInspection() {
     override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean): PsiElementVisitor {
         return referenceExpressionVisitor(fun(expression) {
             val parent = expression.parent as? KtDotQualifiedExpression ?: return
             if (expression == parent.selectorExpression && parent.parent !is KtDotQualifiedExpression) return
+            if (parent.getStrictParentOfType<KtImportDirective>() != null) return
 
-            val descriptor = (expression.mainReference.resolve() as? KtObjectDeclaration)?.descriptor ?: return
+            val objectDeclaration = expression.mainReference.resolve() as? KtObjectDeclaration ?: return
-            if (!DescriptorUtils.isCompanionObject(descriptor)) return
+            if (!objectDeclaration.isCompanion()) return
+            if (expression.text != objectDeclaration.name) return
 
-            if (expression == parent.receiverExpression && expression.text == descriptor.containingDeclaration?.name?.asString()) return
+            val grandParent = parent.parent as? KtQualifiedExpression
+            if (grandParent != null) {
+                val grandParentDescriptor = grandParent.resolveToCall()?.resultingDescriptor ?: return
+                if (grandParentDescriptor is ConstructorDescriptor) return
+            }
 
             holder.registerProblem(
                 expression,

idea/testData/inspectionsLocal/redundantCompanionReference/companionDoubleNested.kt

@@ -0,0 +1,11 @@
+// PROBLEM: none
+
+class Owner {
+    companion object {
+        class InCompanion {
+            class Nested
+        }
+    }
+}
+
+val y = Owner.<caret>Companion.InCompanion.Nested()

idea/testData/inspectionsLocal/redundantCompanionReference/companionNested.kt

@@ -0,0 +1,9 @@
+// PROBLEM: none
+
+class Owner {
+    companion object {
+        class InCompanion
+    }
+}
+
+val y = Owner.<caret>Companion.InCompanion()

idea/testData/inspectionsLocal/redundantCompanionReference/import.kt

@@ -0,0 +1,13 @@
+// PROBLEM: none
+
+import Owner.<caret>Companion.some
+
+class Owner {
+    companion object {
+        const val some = ""
+    }
+}
+
+class User {
+    val anything = some
+}

idea/testData/inspectionsLocal/redundantCompanionReference/named.kt

@@ -0,0 +1,9 @@
+class C {
+    companion object Obj {
+        fun create() = C()
+    }
+}
+
+fun test() {
+    C.<caret>Obj.create()
+}

idea/testData/inspectionsLocal/redundantCompanionReference/named.kt.after

@@ -0,0 +1,9 @@
+class C {
+    companion object Obj {
+        fun create() = C()
+    }
+}
+
+fun test() {
+    C.create()
+}

idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -2553,6 +2553,18 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("companionDoubleNested.kt")
+        public void testCompanionDoubleNested() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/redundantCompanionReference/companionDoubleNested.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("companionNested.kt")
+        public void testCompanionNested() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/redundantCompanionReference/companionNested.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("directCompanion.kt")
         public void testDirectCompanion() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/redundantCompanionReference/directCompanion.kt");
@@ -2565,12 +2577,24 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("import.kt")
+        public void testImport() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/redundantCompanionReference/import.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("methodArgument.kt")
         public void testMethodArgument() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/redundantCompanionReference/methodArgument.kt");
             doTest(fileName);
         }
 
+        @TestMetadata("named.kt")
+        public void testNamed() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/redundantCompanionReference/named.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("notCompanion.kt")
         public void testNotCompanion() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/redundantCompanionReference/notCompanion.kt");