Test annotated struct narrowing

src/tyro/_fields.py

@@ -186,12 +186,12 @@ def with_new_type_stripped(
         self, new_type_stripped: TypeForm[Any] | Callable
     ) -> FieldDefinition:
         if get_origin(self.type) is Annotated:
-            new_type = Annotated[(new_type_stripped, *get_args(self.type)[1:])]
+            new_type = Annotated[(new_type_stripped, *get_args(self.type)[1:])]  # type: ignore
         else:
-            new_type = new_type_stripped
+            new_type = new_type_stripped  # type: ignore
         return dataclasses.replace(
             self,
-            type=new_type,
+            type=new_type,  # type: ignore
             type_stripped=new_type_stripped,
         )
 

tests/test_nested.py

@@ -2,11 +2,11 @@
 from typing import Any, Generic, Mapping, NewType, Optional, Tuple, TypeVar, Union
 
 import pytest
+import tyro
 from frozendict import frozendict  # type: ignore
-from helptext_utils import get_helptext_with_checks
 from typing_extensions import Annotated, Final, Literal
 
-import tyro
+from helptext_utils import get_helptext_with_checks
 
 
 def test_nested() -> None:
@@ -1231,3 +1231,18 @@ class Args:
 
     assert tyro.cli(Args, args=[]) == Args(A("hello"))
     assert "default: inner:alt" in get_helptext_with_checks(Args)
+
+
+def test_annotated_narrow() -> None:
+    @dataclasses.dataclass
+    class A: ...
+
+    @dataclasses.dataclass
+    class B(A):
+        x: int
+
+    def main(x: Annotated[A, tyro.conf.OmitArgPrefixes] = B(x=3)) -> Any:
+        return x
+
+    assert tyro.cli(main, args=[]) == B(x=3)
+    assert tyro.cli(main, args="--x 5".split(" ")) == B(x=5)

tests/test_py311_generated/test_nested_generated.py

@@ -1241,3 +1241,18 @@ class Args:
 
     assert tyro.cli(Args, args=[]) == Args(A("hello"))
     assert "default: inner:alt" in get_helptext_with_checks(Args)
+
+
+def test_annotated_narrow() -> None:
+    @dataclasses.dataclass
+    class A: ...
+
+    @dataclasses.dataclass
+    class B(A):
+        x: int
+
+    def main(x: Annotated[A, tyro.conf.OmitArgPrefixes] = B(x=3)) -> Any:
+        return x
+
+    assert tyro.cli(main, args=[]) == B(x=3)
+    assert tyro.cli(main, args="--x 5".split(" ")) == B(x=5)