Fixed bug that caused false positive when evaluating type compatibility between two TypedDict types that are structurally the same but have different declarations. PEP 589 indicates that these should be treated as compatible types.

packages/pyright-internal/src/analyzer/typeEvaluator.ts

@@ -17338,10 +17338,16 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
         // Handle typed dicts. They also use a form of structural typing for type
         // checking, as defined in PEP 589.
         if (ClassType.isTypedDictClass(destType) && ClassType.isTypedDictClass(srcType)) {
-            if ((flags & CanAssignFlags.EnforceInvariance) !== 0 && !ClassType.isSameGenericClass(destType, srcType)) {
+            if (!canAssignTypedDict(evaluatorInterface, destType, srcType, diag, recursionCount)) {
                 return false;
             }
-            return canAssignTypedDict(evaluatorInterface, destType, srcType, diag, recursionCount);
+
+            // If invariance is being enforced, the two TypedDicts must be assignable to each other.
+            if ((flags & CanAssignFlags.EnforceInvariance) !== 0 && !ClassType.isSameGenericClass(destType, srcType)) {
+                return canAssignTypedDict(evaluatorInterface, srcType, destType, /* diag */ undefined, recursionCount);
+            }
+
+            return true;
         }
 
         // Handle special-case type promotions.

packages/pyright-internal/src/tests/samples/typedDict16.py

@@ -0,0 +1,80 @@
+# This sample tests that type compatibility between TypedDicts.
+
+from typing import List, TypedDict
+
+
+class TD0(TypedDict):
+    key: str
+
+
+class TD1(TD0):
+    value: str
+
+
+class TD2(TypedDict):
+    key: str
+    value: str
+
+
+v1: TD2 = TD1(key="", value="")
+v2: TD1 = TD2(key="", value="")
+
+v3 = [v2]
+v4: List[TD2] = v3
+v5 = [v1]
+v6: List[TD1] = v5
+
+
+class TD10(TypedDict, total=False):
+    key: str
+
+
+class TD11(TD10):
+    value: str
+
+
+class TD12(TypedDict):
+    key: str
+    value: str
+
+
+# This should generate an error.
+v10: TD12 = TD11(key="", value="")
+
+# This should generate an error.
+v11: TD11 = TD12(key="", value="")
+
+
+v12 = [v10]
+# This should generate an error.
+v13: List[TD10] = v12
+
+v14 = [v11]
+# This should generate an error.
+v15: List[TD12] = v14
+
+
+class TD20(TypedDict):
+    key: str
+    value: str
+
+
+class TD21(TypedDict):
+    key: str
+    value: str
+    extra: str
+
+
+# This should generate an error.
+v20: TD21 = TD20(key="", value="")
+
+v21: TD20 = TD21(key="", value="", extra="")
+
+
+v22 = [v20]
+# This should generate an error.
+v23: List[TD20] = v22
+
+v24: List[TD20] = [v21]
+# This should generate an error.
+v25: List[TD21] = v24

packages/pyright-internal/src/tests/typeEvaluator2.test.ts

@@ -986,3 +986,9 @@ test('TypedDict15', () => {
 
     TestUtils.validateResults(analysisResults, 2);
 });
+
+test('TypedDict16', () => {
+    const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typedDict16.py']);
+
+    TestUtils.validateResults(analysisResults, 7);
+});