Fix completion private members described in stubs (PY-27146)

No more private element filtering in CompletionVariantsProcessor, let's leave it for types.

python/src/com/jetbrains/python/inspections/PyProtectedMemberInspection.java

@@ -157,13 +157,7 @@ public class PyProtectedMemberInspection extends PyInspection {
     @Nullable
     private PyClass getNotPyiClassOwner(@Nullable PsiElement element) {
       final PyClass owner = getClassOwner(element);
-      if (owner != null) {
-        final PsiElement originalOwner = PyiUtil.getOriginalElement(owner);
-        if (originalOwner instanceof PyClass) {
-          return (PyClass)originalOwner;
-        }
-      }
-      return owner;
+      return owner == null ? null : PyiUtil.stubToOriginal(owner, PyClass.class);
     }
 
     @Nullable

python/src/com/jetbrains/python/psi/impl/references/PyQualifiedReference.java

@@ -128,10 +128,9 @@ public class PyQualifiedReference extends PyReferenceImpl {
       return true;
     }
     if (match.size() > 1) {
-      final PyClass ourClass = qualifierType.getPyClass();
-      final PsiElement originalOurClass = PyiUtil.getOriginalElement(ourClass);
+      final PyClass ourClass = PyiUtil.stubToOriginal(qualifierType.getPyClass(), PyClass.class);
       final PsiElement theirClass = CompletionUtil.getOriginalOrSelf(match.get(match.size() - 1));
-      if (originalOurClass != null && originalOurClass != theirClass || originalOurClass == null && ourClass != theirClass) return true;
+      if (ourClass != theirClass) return true;
     }
     return false;
   }

python/src/com/jetbrains/python/psi/resolve/CompletionVariantsProcessor.java

@@ -156,9 +156,6 @@ public class CompletionVariantsProcessor extends VariantsProcessor {
 
   @Override
   protected void addElement(@NotNull String name, @NotNull PsiElement element) {
-    if (PyUtil.isClassPrivateName(name) && !PyUtil.inSameFile(element, myContext)) {
-      return;
-    }
     markAsProcessed(name);
     myVariants.put(name, setupItem(LookupElementBuilder.createWithSmartPointer(name, element).withIcon(element.getIcon(0))));
   }

python/src/com/jetbrains/python/psi/types/PyClassTypeImpl.java

@@ -30,6 +30,7 @@ import com.jetbrains.python.psi.resolve.CompletionVariantsProcessor;
 import com.jetbrains.python.psi.resolve.PyResolveContext;
 import com.jetbrains.python.psi.resolve.PyResolveProcessor;
 import com.jetbrains.python.psi.resolve.RatedResolveResult;
+import com.jetbrains.python.pyi.PyiUtil;
 import com.jetbrains.python.toolbox.Maybe;
 import one.util.streamex.StreamEx;
 import org.jetbrains.annotations.NotNull;
@@ -788,7 +789,7 @@ public class PyClassTypeImpl extends UserDataHolderBase implements PyClassType {
     if (containingClass != null) {
       containingClass = CompletionUtil.getOriginalElement(containingClass);
     }
-    boolean withinOurClass = containingClass == getPyClass() || isInSuperCall(expressionHook);
+    final boolean withinOurClass = containingClass == PyiUtil.stubToOriginal(getPyClass(), PyClass.class) || isInSuperCall(expressionHook);
 
     final CompletionVariantsProcessor processor = new CompletionVariantsProcessor(
       expressionHook, new FilterNotInstance(myClass), null, false, suppressParentheses
@@ -808,7 +809,7 @@ public class PyClassTypeImpl extends UserDataHolderBase implements PyClassType {
     for (LookupElement le : processor.getResultList()) {
       String name = le.getLookupString();
       if (namesAlready.contains(name)) continue;
-      if (!withinOurClass && isClassPrivate(name)) continue;
+      if (!withinOurClass && PyUtil.isClassPrivateName(name)) continue;
       if (!withinOurClass && isClassProtected(name) && prefix == null) continue;
       namesAlready.add(name);
       ret.add(le);
@@ -849,7 +850,7 @@ public class PyClassTypeImpl extends UserDataHolderBase implements PyClassType {
       Object[] ancestry = type.getCompletionVariants(name, expressionHook, context);
       for (Object ob : ancestry) {
         String inheritedName = ob.toString();
-        if (!namesAlready.contains(inheritedName) && !isClassPrivate(inheritedName)) {
+        if (!namesAlready.contains(inheritedName) && !PyUtil.isClassPrivateName(inheritedName)) {
           ret.add(ob);
           namesAlready.add(inheritedName);
         }
@@ -858,10 +859,6 @@ public class PyClassTypeImpl extends UserDataHolderBase implements PyClassType {
     }
   }
 
-  private static boolean isClassPrivate(String lookup_string) {
-    return lookup_string.startsWith("__") && !lookup_string.endsWith("__");
-  }
-
   private static boolean isClassProtected(@NotNull final String lookupString) {
     return lookupString.startsWith("_") && !lookupString.startsWith("__");
   }

python/src/com/jetbrains/python/pyi/PyiUtil.java

@@ -125,6 +125,15 @@ public class PyiUtil {
            PyKnownDecoratorUtil.getKnownDecorators((PyFunction)element, context).contains(overload);
   }
 
+  @NotNull
+  public static <T extends PyElement> T stubToOriginal(@NotNull T element, @NotNull Class<T> cls) {
+    final PsiElement originalElement = getOriginalElement(element);
+    if (cls.isInstance(originalElement)) {
+      return cls.cast(originalElement);
+    }
+    return element;
+  }
+
   private static boolean pyButNotPyiFile(@Nullable PsiFile file) {
     return file instanceof PyFile && !(file instanceof PyiFile);
   }

python/testData/completion/privateMemberOwnerResolvedToStub/a.after.py

@@ -0,0 +1,12 @@
+class Test:
+    @classmethod
+    def foo(cls):
+        return cls._bar(), cls.__egg()
+
+    @staticmethod
+    def _bar():
+        pass
+
+    @staticmethod
+    def __egg():
+        pass

python/testData/completion/privateMemberOwnerResolvedToStub/a.py

@@ -0,0 +1,12 @@
+class Test:
+    @classmethod
+    def foo(cls):
+        return cls._bar(), cls.__eg<caret>
+
+    @staticmethod
+    def _bar():
+        pass
+
+    @staticmethod
+    def __egg():
+        pass

python/testData/completion/privateMemberOwnerResolvedToStub/a.pyi

@@ -0,0 +1,7 @@
+class Test:
+    @classmethod
+    def foo(cls): ...
+    @staticmethod
+    def _bar(): ...
+    @staticmethod
+    def __egg(): ...

python/testSrc/com/jetbrains/python/PythonCompletionTest.java

@@ -1194,6 +1194,11 @@ public class PythonCompletionTest extends PyTestCase {
     assertDoesntContain(variants, "bar=");
   }
 
+  // PY-27146
+  public void testPrivateMemberOwnerResolvedToStub() {
+    doMultiFileTest();
+  }
+
   @Override
   protected String getTestDataPath() {
     return super.getTestDataPath() + "/completion";