TypeAlias return type for functions that create types to avoid mypy errors (#671)

Author: mauvilsa

CHANGELOG.rst

@@ -29,6 +29,8 @@ Fixed
   <https://github.com/omni-us/jsonargparse/pull/667>`__).
 - Failure when a link target has an undefined parent (`#668
   <https://github.com/omni-us/jsonargparse/pull/668>`__)
+- Functions that create types now have ``TypeAlias`` return type to avoid mypy
+  errors (`#671 <https://github.com/omni-us/jsonargparse/pull/671>`__).
 
 
 v4.36.0 (2025-01-17)

jsonargparse/typing.py

@@ -5,8 +5,14 @@
 import os
 import pathlib
 import re
+import sys
 from typing import Any, Callable, Dict, List, Optional, Pattern, Tuple, Type, Union
 
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias as _TypeAlias
+else:
+    _TypeAlias = type
+
 from ._common import is_final_class
 from ._optionals import final, pydantic_support
 from ._util import Path, get_import_path, get_private_kwargs, import_object
@@ -58,7 +64,7 @@ def extend_base_type(
     docstring: Optional[str] = None,
     extra_attrs: Optional[dict] = None,
     register_key: Optional[Tuple] = None,
-) -> type:
+) -> _TypeAlias:
     """Creates and registers an extension of base type.
 
     Args:
@@ -103,7 +109,7 @@ def restricted_number_type(
     restrictions: Union[Tuple, List[Tuple]],
     join: str = "and",
     docstring: Optional[str] = None,
-) -> type:
+) -> _TypeAlias:
     """Creates or returns an already registered restricted number type class.
 
     Args:
@@ -174,7 +180,7 @@ def restricted_string_type(
     name: str,
     regex: Union[str, Pattern],
     docstring: Optional[str] = None,
-) -> type:
+) -> _TypeAlias:
     """Creates or returns an already registered restricted string type class.
 
     Args:
@@ -213,7 +219,7 @@ def _is_path_type(value, type_class):
     return isinstance(value, Path)
 
 
-def path_type(mode: str, docstring: Optional[str] = None, **kwargs) -> type:
+def path_type(mode: str, docstring: Optional[str] = None, **kwargs) -> _TypeAlias:
     """Creates or returns an already registered path type class.
 
     Args:

jsonargparse_tests/test_dataclass_like.py

@@ -39,7 +39,7 @@ class DataClassA:
         a2: a2 help
     """
 
-    a1: PositiveInt = PositiveInt(1)  # type: ignore[valid-type]
+    a1: PositiveInt = PositiveInt(1)
     a2: str = "2"
 
 
@@ -52,7 +52,7 @@ class DataClassB:
         b2: b2 help
     """
 
-    b1: PositiveFloat = PositiveFloat(3.0)  # type: ignore[valid-type]
+    b1: PositiveFloat = PositiveFloat(3.0)
     b2: DataClassA = DataClassA(a2="x")
 
 

jsonargparse_tests/test_postponed_annotations.py

@@ -345,7 +345,7 @@ def test_get_types_dataclass_pep585(parser):
 
 @dataclasses.dataclass
 class DataWithInit585(Data585):
-    def __init__(self, b: Path_drw, **kwargs):  # type: ignore[valid-type]
+    def __init__(self, b: Path_drw, **kwargs):
         super().__init__(b=os.fspath(b), **kwargs)
 
 

jsonargparse_tests/test_typehints.py

@@ -1386,7 +1386,7 @@ def test_action_typehint_none_type_error():
         (Dict[bool, type(None)], bool, False),  # type: ignore[misc]
         (Optional[Path_fr], Path_fr, True),
         (Union[type(None), Path_fr], Path_fr, True),
-        (Dict[Path_fr, type(None)], Path_fr, False),  # type: ignore[misc,valid-type]
+        (Dict[Path_fr, type(None)], Path_fr, False),  # type: ignore[misc]
         (Optional[EnumABC], Enum, True),
         (Union[type(None), EnumABC], Enum, True),
         (Dict[EnumABC, type(None)], Enum, False),  # type: ignore[misc]