From f7da96db034fea606618bb2b384b14f68db55475 Mon Sep 17 00:00:00 2001
From: Mikhail Golubev <mikhail.golubev@jetbrains.com>
Date: Tue, 19 Dec 2017 17:19:06 +0300
Subject: [PATCH] PY-27656 PY-27604 Exclude ancestors of metaclasses from class
 hierarchy

in case this relationship was created implicitly by inheriting an
instance of metaclass.

It also fixes warnings about the first parameter of SQLAlchemy model
methods being named "self" instead of "cls" since we no longer consider
these classes descendants of "type".
---
 .../jetbrains/python/psi/impl/PyClassImpl.java  | 17 ++++++++++++++++-
 .../DirectlyInstantiatedMetaclassAncestor.py    | 13 +++++++++++++
 .../python/codeInsight/PyClassMROTest.java      |  5 +++++
 3 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 python/testData/codeInsight/classMRO/DirectlyInstantiatedMetaclassAncestor.py

diff --git a/python/src/com/jetbrains/python/psi/impl/PyClassImpl.java b/python/src/com/jetbrains/python/psi/impl/PyClassImpl.java
index 09fe1bd98699..24b3ed199cdd 100644
--- a/python/src/com/jetbrains/python/psi/impl/PyClassImpl.java
+++ b/python/src/com/jetbrains/python/psi/impl/PyClassImpl.java
@@ -427,7 +427,22 @@ public class PyClassImpl extends PyBaseElementImpl<PyClassStub> implements PyCla
       final List<List<PyClassLikeType>> lines = new ArrayList<>();
       for (PyClassLikeType base : bases) {
         if (base != null) {
-          final List<PyClassLikeType> baseClassMRO = mroLinearize(base, true, context, cache);
+          // Don't include ancestors of a metaclass instance
+          final List<PyClassLikeType> baseClassMRO;
+          if (base.isDefinition()) {
+            baseClassMRO = mroLinearize(base, true, context, cache);
+          }
+          else {
+            List<PyClassLikeType> metaclassInstanceMro = new ArrayList<>();
+            metaclassInstanceMro.add(base);
+            if (base instanceof PyClassType) {
+              final PyClassImpl pyClass = as(((PyClassType)base).getPyClass(), PyClassImpl.class);
+              if (pyClass != null) {
+                ContainerUtil.addIfNotNull(metaclassInstanceMro, pyClass.getImplicitSuper(context));
+              }
+            }
+            baseClassMRO = metaclassInstanceMro;
+          }
           if (!baseClassMRO.isEmpty()) {
             // mroMerge() updates passed MRO lists internally
             lines.add(new LinkedList<>(baseClassMRO));
diff --git a/python/testData/codeInsight/classMRO/DirectlyInstantiatedMetaclassAncestor.py b/python/testData/codeInsight/classMRO/DirectlyInstantiatedMetaclassAncestor.py
new file mode 100644
index 000000000000..1382eff7461b
--- /dev/null
+++ b/python/testData/codeInsight/classMRO/DirectlyInstantiatedMetaclassAncestor.py
@@ -0,0 +1,13 @@
+class MetaBase(type):
+    pass
+
+
+class Meta(MetaBase):
+    pass
+
+
+Base = Meta('Base', (), {})
+
+
+class MyClass(Base):
+    pass
\ No newline at end of file
diff --git a/python/testSrc/com/jetbrains/python/codeInsight/PyClassMROTest.java b/python/testSrc/com/jetbrains/python/codeInsight/PyClassMROTest.java
index 1fcc619a197d..53e485b6bb9f 100644
--- a/python/testSrc/com/jetbrains/python/codeInsight/PyClassMROTest.java
+++ b/python/testSrc/com/jetbrains/python/codeInsight/PyClassMROTest.java
@@ -125,6 +125,11 @@ public class PyClassMROTest extends PyTestCase {
     assertMRO(getClass("MyClass"), "Base", "object");
   }
 
+  // PY-27656
+  public void testDirectlyInstantiatedMetaclassAncestor() {
+    runWithLanguageLevel(LanguageLevel.PYTHON30, () -> assertMRO(getClass("MyClass"), "Meta", "object"));
+  }
+
   // PY-20026
   public void testUnresolvedMetaClassAncestors() {
     runWithLanguageLevel(LanguageLevel.PYTHON30, () -> assertMRO(getClass("CompositeFieldMeta"), "type", "object"));