From 1dfa08e124b40e24d49fc6f534e0ff29c94e4c51 Mon Sep 17 00:00:00 2001
From: Semyon Proshev <Semyon.Proshev@jetbrains.com>
Date: Fri, 10 Nov 2017 22:57:37 +0300
Subject: [PATCH] Collect metaclass members while calculating class member
 names (PY-21408)

---
 .../python/psi/types/PyClassTypeImpl.java     | 27 ++++++++++++++
 .../ClassMetaAttrsAgainstStructural.py        | 37 +++++++++++++++++++
 .../PyTypeCheckerInspectionTest.java          |  5 +++
 3 files changed, 69 insertions(+)
 create mode 100644 python/testData/inspections/PyTypeCheckerInspection/ClassMetaAttrsAgainstStructural.py

diff --git a/python/src/com/jetbrains/python/psi/types/PyClassTypeImpl.java b/python/src/com/jetbrains/python/psi/types/PyClassTypeImpl.java
index 3e5fdf02eb42..1d17b87cfc8c 100644
--- a/python/src/com/jetbrains/python/psi/types/PyClassTypeImpl.java
+++ b/python/src/com/jetbrains/python/psi/types/PyClassTypeImpl.java
@@ -662,6 +662,9 @@ public class PyClassTypeImpl extends UserDataHolderBase implements PyClassType {
   @NotNull
   @Override
   public Set<String> getMemberNames(boolean inherited, @NotNull TypeEvalContext context) {
+    // PyNamedTupleType.getMemberNames provide names that we are not able to visit,
+    // so this method could not be replaced with PyClassLikeType.visitMembers
+
     final Set<String> result = new LinkedHashSet<>();
 
     for (PyFunction function : myClass.getMethods()) {
@@ -692,11 +695,35 @@ public class PyClassTypeImpl extends UserDataHolderBase implements PyClassType {
           result.addAll(ancestorType.getMemberNames(false, context));
         }
       }
+
+      result.addAll(getMetaClassMemberNames(context));
     }
 
     return result;
   }
 
+  @NotNull
+  private Set<String> getMetaClassMemberNames(@NotNull TypeEvalContext context) {
+    if (!myClass.isNewStyleClass(context)) {
+      return Collections.emptySet();
+    }
+
+    final PyClassLikeType typeType = getMetaClassType(context, true);
+    if (typeType == null) {
+      return Collections.emptySet();
+    }
+
+    if (isDefinition()) {
+      return typeType.getMemberNames(true, context);
+    }
+    else if (typeType instanceof PyClassType) {
+      final List<PyTargetExpression> typeInstanceAttributes = ((PyClassType)typeType).getPyClass().getInstanceAttributes();
+      return ContainerUtil.map2SetNotNull(typeInstanceAttributes, PyTargetExpression::getName);
+    }
+
+    return Collections.emptySet();
+  }
+
   private void addOwnClassMembers(PsiElement expressionHook,
                                   Set<String> namesAlready,
                                   boolean suppressParentheses,
diff --git a/python/testData/inspections/PyTypeCheckerInspection/ClassMetaAttrsAgainstStructural.py b/python/testData/inspections/PyTypeCheckerInspection/ClassMetaAttrsAgainstStructural.py
new file mode 100644
index 000000000000..d3b014b102fc
--- /dev/null
+++ b/python/testData/inspections/PyTypeCheckerInspection/ClassMetaAttrsAgainstStructural.py
@@ -0,0 +1,37 @@
+class B1(type):
+    meta_attr = "meta_attr"
+
+
+class A1(metaclass=B1):
+    pass
+
+
+def print_A1(a):
+    print(a.__name__)
+    print(a.meta_attr)
+
+
+def print_unknown(a):
+    print(a.unknown)
+
+
+print_A1(A1)
+print_unknown(<warning descr="Type 'Type[A1]' doesn't have expected attribute 'unknown'">A1</warning>)
+
+
+class B2(type):
+    def __init__(self, what, bases, dict):
+        self.meta_attr = "meta_attr"
+        super().__init__(what, bases, dict)
+
+
+class A2(metaclass=B2):
+    pass
+
+
+def print_A2(a):
+    print(a.meta_attr)
+
+
+print_A2(A2())
+print_unknown(<warning descr="Type 'A2' doesn't have expected attribute 'unknown'">A2()</warning>)
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java
index cb9e1f605b54..0a7dd0d0f99d 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java
@@ -446,4 +446,9 @@ public class PyTypeCheckerInspectionTest extends PyInspectionTestCase {
   public void testMatchingOpenFunctionCallTypesPy2() {
     doMultiFileTest();
   }
+
+  // PY-21408
+  public void testClassMetaAttrsAgainstStructural() {
+    runWithLanguageLevel(LanguageLevel.PYTHON30, this::doTest);
+  }
 }