KT-12797: Fix completion to show inner classes from base class

#KT-12797 fixed

idea/ide-common/src/org/jetbrains/kotlin/idea/codeInsight/ReferenceVariantsHelper.kt

@@ -269,7 +269,11 @@ class ReferenceVariantsHelper(
         }
         else {
             // process non-instance members and class constructors
-            descriptors.addNonExtensionCallablesAndConstructors(resolutionScope, kindFilter, nameFilter, constructorFilter = { !it.isInner })
+            descriptors.addNonExtensionCallablesAndConstructors(
+                    resolutionScope,
+                    kindFilter, nameFilter, constructorFilter = { !it.isInner },
+                    classesOnly = false
+            )
         }
         return descriptors
     }
@@ -328,7 +332,18 @@ class ReferenceVariantsHelper(
             constructorFilter: (ClassDescriptor) -> Boolean
     ) {
         for (receiverType in receiverTypes) {
-            addNonExtensionCallablesAndConstructors(receiverType.memberScope.memberScopeAsImportingScope(), kindFilter, nameFilter, constructorFilter)
+            addNonExtensionCallablesAndConstructors(
+                    receiverType.memberScope.memberScopeAsImportingScope(),
+                    kindFilter, nameFilter, constructorFilter,
+                    false
+            )
+            receiverType.constructor.supertypes.forEach {
+                addNonExtensionCallablesAndConstructors(
+                        it.memberScope.memberScopeAsImportingScope(),
+                        kindFilter, nameFilter, constructorFilter,
+                        true
+                )
+            }
         }
     }
 
@@ -336,7 +351,8 @@ class ReferenceVariantsHelper(
             scope: HierarchicalScope,
             kindFilter: DescriptorKindFilter,
             nameFilter: (Name) -> Boolean,
-            constructorFilter: (ClassDescriptor) -> Boolean
+            constructorFilter: (ClassDescriptor) -> Boolean,
+            classesOnly: Boolean
     ) {
         var filterToUse = DescriptorKindFilter(kindFilter.kindMask and DescriptorKindFilter.CALLABLES.kindMask).exclude(DescriptorKindExclude.Extensions)
 
@@ -351,7 +367,7 @@ class ReferenceVariantsHelper(
                 if (!constructorFilter(descriptor)) continue
                 descriptor.constructors.filterTo(this) { kindFilter.accepts(it) }
             }
-            else if (kindFilter.accepts(descriptor)) {
+            else if (!classesOnly && kindFilter.accepts(descriptor)) {
                 this.add(descriptor)
             }
         }

idea/idea-completion/testData/basic/common/InnerInBaseClass.kt

@@ -0,0 +1,15 @@
+
+abstract class A {
+    inner class InnerInA
+}
+
+abstract class B : A() {
+    inner class InnerInB
+}
+
+fun foo(b: B) {
+    val v = b.InnerIn<caret>
+}
+
+// EXIST: InnerInB
+// EXIST: InnerInA

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/JSBasicCompletionTestGenerated.java

@@ -470,6 +470,12 @@ public class JSBasicCompletionTestGenerated extends AbstractJSBasicCompletionTes
             doTest(fileName);
         }
 
+        @TestMetadata("InnerInBaseClass.kt")
+        public void testInnerInBaseClass() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/InnerInBaseClass.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("InsideAnonymousClass.kt")
         public void testInsideAnonymousClass() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/InsideAnonymousClass.kt");

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/JvmBasicCompletionTestGenerated.java

@@ -470,6 +470,12 @@ public class JvmBasicCompletionTestGenerated extends AbstractJvmBasicCompletionT
             doTest(fileName);
         }
 
+        @TestMetadata("InnerInBaseClass.kt")
+        public void testInnerInBaseClass() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/InnerInBaseClass.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("InsideAnonymousClass.kt")
         public void testInsideAnonymousClass() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/InsideAnonymousClass.kt");