return weak type of class as return type of constructor call if the actual return type of __new__ is unknown (PY-6671)

python/src/com/jetbrains/python/psi/impl/PyCallExpressionImpl.java

@@ -162,6 +162,12 @@ public class PyCallExpressionImpl extends PyElementImpl implements PyCallExpress
               }
             }
             if (t != null && !(t instanceof PyNoneType)) {
+              if (t instanceof PyTypeReference) {
+                PyType resolved = ((PyTypeReference)t).resolve(callee, context);
+                if (resolved == null) {
+                  return new PyWeakClassType(cls, false);
+                }
+              }
               return t;
             }
           }

python/testData/completion/unknownNewReturnType.after.py

@@ -0,0 +1,11 @@
+def foo(): return foo()
+
+class Template(object):
+    def __new__(cls):
+        return foo()
+
+    def xyzzy(self):
+        pass
+
+t = Template()
+t.xyzzy()

python/testData/completion/unknownNewReturnType.py

@@ -0,0 +1,11 @@
+def foo(): return foo()
+
+class Template(object):
+    def __new__(cls):
+        return foo()
+
+    def xyzzy(self):
+        pass
+
+t = Template()
+t.x<caret>

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

@@ -584,4 +584,8 @@ public class PythonCompletionTest extends PyTestCase {
   public void testNoInitForSubmodules() {
     doMultiFileTest();
   }
+
+  public void testUnknownNewReturnType() {  // PY-6671
+    doTest();
+  }
 }