From 315031a47bb28bada6d583fb7adf820f024dcf27 Mon Sep 17 00:00:00 2001
From: Eric Traut <erictr@microsoft.com>
Date: Sun, 5 Mar 2023 23:10:19 -0700
Subject: [PATCH] Fixed a bug that led to a false positive error when using a
 subclass of `type` as a base class in a class declaration. This addresses
 https://github.com/microsoft/pyright/issues/4737.

---
 .../pyright-internal/src/analyzer/typeEvaluator.ts  |  8 +++++++-
 packages/pyright-internal/src/analyzer/typeUtils.ts | 13 ++++++++++---
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/packages/pyright-internal/src/analyzer/typeEvaluator.ts b/packages/pyright-internal/src/analyzer/typeEvaluator.ts
index 621dc2f22..dcc57b392 100644
--- a/packages/pyright-internal/src/analyzer/typeEvaluator.ts
+++ b/packages/pyright-internal/src/analyzer/typeEvaluator.ts
@@ -15983,7 +15983,13 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
                 }
 
                 if (!isAnyOrUnknown(argType) && !isUnbound(argType)) {
-                    if (isClass(argType) && TypeBase.isInstance(argType) && ClassType.isBuiltIn(argType, 'type')) {
+                    if (
+                        isClass(argType) &&
+                        TypeBase.isInstance(argType) &&
+                        argType.details.mro.some(
+                            (mroClass) => isClass(mroClass) && ClassType.isBuiltIn(mroClass, 'type')
+                        )
+                    ) {
                         argType =
                             argType.typeArguments && argType.typeArguments.length > 0
                                 ? argType.typeArguments[0]
diff --git a/packages/pyright-internal/src/analyzer/typeUtils.ts b/packages/pyright-internal/src/analyzer/typeUtils.ts
index 2bc234b8b..44dc96773 100644
--- a/packages/pyright-internal/src/analyzer/typeUtils.ts
+++ b/packages/pyright-internal/src/analyzer/typeUtils.ts
@@ -1987,9 +1987,16 @@ export function isEffectivelyInstantiable(type: Type): boolean {
         return true;
     }
 
-    // Handle the special case of 'type', which is instantiable.
-    if (isClassInstance(type) && ClassType.isBuiltIn(type, 'type')) {
-        return true;
+    // Handle the special case of 'type' (or subclasses thereof),
+    // which are instantiable.
+    if (isClassInstance(type)) {
+        if (
+            type.details.mro.some((mroClass) => {
+                return isClass(mroClass) && ClassType.isBuiltIn(mroClass, 'type');
+            })
+        ) {
+            return true;
+        }
     }
 
     if (isUnion(type)) {