Fixed recent regression that results in incorrect narrowed type when …

…using the `x in y` pattern where `y` is a container type whose element type is `Unknown` or `Any`. This addresses #9457.

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

@@ -2060,7 +2060,7 @@ export function getElementTypeForContainerNarrowing(containerType: Type) {
 export function narrowTypeForContainerElementType(evaluator: TypeEvaluator, referenceType: Type, elementType: Type) {
     return evaluator.mapSubtypesExpandTypeVars(referenceType, /* options */ undefined, (referenceSubtype) => {
         return mapSubtypes(elementType, (elementSubtype) => {
-            if (isAnyOrUnknown(referenceSubtype)) {
+            if (isAnyOrUnknown(elementSubtype)) {
                 return referenceSubtype;
             }
 

packages/pyright-internal/src/tests/samples/typeNarrowingIn1.py

@@ -1,40 +1,22 @@
 # This sample tests type narrowing for the "in" operator.
 
-from typing import Callable, Generic, Literal, ParamSpec, TypeVar, TypedDict
+from typing import Any, Callable, Generic, Literal, ParamSpec, TypeVar, TypedDict
 import random
 
 
-def verify_str(p: str) -> None: ...
-
-
-def verify_int(p: int) -> None: ...
-
-
-def verify_none(p: None) -> None: ...
-
-
-x: str | None
-y: int | str
-if random.random() < 0.5:
-    x = None
-    y = 1
-else:
-    x = "2"
-    y = "2"
-
-if x in ["2"]:
-    verify_str(x)
-
-    # This should generate an error because x should
-    # be narrowed to a str.
-    verify_none(x)
+def func0(x: str | None, y: int | str):
+    if random.random() < 0.5:
+        x = None
+        y = 1
+    else:
+        x = "2"
+        y = "2"
 
-if y in [2]:
-    verify_int(y)
+    if x in ["2"]:
+        reveal_type(x, expected_text="Literal['2']")
 
-    # This should generate an error because y should
-    # be narrowed to an int.
-    verify_str(y)
+    if y in [1]:
+        reveal_type(y, expected_text="Literal[1]")
 
 
 def func1(x: int | str | None, y: Literal[1, 2, "b"], b: int):
@@ -184,3 +166,13 @@ def func13(x: type[T13]) -> type[T13]:
         reveal_type(x, expected_text="type[str]* | type[int]* | type[float]*")
 
     return x
+
+
+def func14(x: str, y: dict[Any, Any]):
+    if x in y:
+        reveal_type(x, expected_text="str")
+
+
+def func15(x: Any, y: dict[str, str]):
+    if x in y:
+        reveal_type(x, expected_text="str")

packages/pyright-internal/src/tests/typeEvaluator1.test.ts

@@ -496,7 +496,7 @@ test('TypeNarrowingTupleLength1', () => {
 test('TypeNarrowingIn1', () => {
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeNarrowingIn1.py']);
 
-    TestUtils.validateResults(analysisResults, 2);
+    TestUtils.validateResults(analysisResults, 0);
 });
 
 test('TypeNarrowingIn2', () => {