Fixed bug that resulted in a false positive error when defining a new…

… type alias using the `TypeAliasType` constructor that defines no new type parameters but references an outer-scoped type parameter in the type alias definition. This addresses #5341.
microsoft · Jun 19, 2023 · b7df200 · b7df200
1 parent d816d00
commit b7df200
Show file tree

Hide file tree

Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/packages/pyright-internal/src/analyzer/typeEvaluator.ts b/packages/pyright-internal/src/analyzer/typeEvaluator.ts
@@ -12009,7 +12009,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
             nameNode,
             valueExpr,
             /* typeParamNodes */ undefined,
-            () => typeParameters
+            () => typeParameters ?? []
         );
     }
 

diff --git a/packages/pyright-internal/src/tests/samples/typeAliasType2.py b/packages/pyright-internal/src/tests/samples/typeAliasType2.py
@@ -1,6 +1,6 @@
 # This sample tests the TypeAliasType constructor.
 
-from typing import Callable, ParamSpec, TypeVar, TypeVarTuple
+from typing import Callable, Generic, ParamSpec, TypeVar, TypeVarTuple
 from typing_extensions import TypeAliasType
 
 T1 = TypeVar("T1")
@@ -45,3 +45,7 @@
 TA7 = TypeAliasType("TA7", TA6)
 
 JSONNode = TypeAliasType("JSONNode", list[JSONNode] | dict[str, JSONNode] | str | float)
+
+
+class A(Generic[T]):
+    L = TypeAliasType("L", list[T])