Workaround for __type_params__ bug in Python 3.12.0

.github/workflows/pytest.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.12.0", "3.13"]
 
     steps:
       - uses: actions/checkout@v2

src/tyro/_resolver.py

@@ -381,12 +381,14 @@ def concretize_type_params(
         typ = resolve_newtype_and_aliases(typ)
         type_from_typevar = {}
         GenericAlias = getattr(types, "GenericAlias", None)
-        while (
-            GenericAlias is not None
-            and isinstance(typ, GenericAlias)
-            and len(getattr(typ, "__type_params__", ())) > 0
-        ):
-            for k, v in zip(typ.__type_params__, get_args(typ)):  # type: ignore
+        while GenericAlias is not None and isinstance(typ, GenericAlias):
+            type_params = getattr(typ, "__type_params__", ())
+            # The __len__ check is for a bug in Python 3.12.0:
+            # https://github.com/brentyi/tyro/issues/235
+            if not hasattr(type_params, "__len__") or len(type_params) == 0:
+                break
+
+            for k, v in zip(type_params, get_args(typ)):
                 type_from_typevar[k] = TypeParamResolver.concretize_type_params(
                     v, seen=seen
                 )

tests/test_new_style_annotations_min_py39.py

@@ -1,7 +1,8 @@
 import dataclasses
-from typing import Any, Literal, Optional, Union
+from typing import Any, Literal, Optional, Type, Union
 
 import pytest
+from helptext_utils import get_helptext_with_checks
 
 import tyro
 
@@ -67,3 +68,33 @@ def main(
 def test_tuple_direct() -> None:
     assert tyro.cli(tuple[int, ...], args="1 2".split(" ")) == (1, 2)  # type: ignore
     assert tyro.cli(tuple[int, int], args="1 2".split(" ")) == (1, 2)  # type: ignore
+
+
+try:
+    from torch.optim.lr_scheduler import LinearLR, LRScheduler
+
+    def test_type_with_init_false() -> None:
+        """https://github.com/brentyi/tyro/issues/235"""
+
+        @dataclasses.dataclass(frozen=True)
+        class LinearLRConfig:
+            _target: type[LRScheduler] = dataclasses.field(
+                init=False, default_factory=lambda: LinearLR
+            )
+            _target2: Type[LRScheduler] = dataclasses.field(
+                init=False, default_factory=lambda: LinearLR
+            )
+            start_factor: float = 1.0 / 3
+            end_factor: float = 1.0
+            total_iters: Optional[int] = None
+
+        def main(config: LinearLRConfig) -> LinearLRConfig:
+            return config
+
+        assert tyro.cli(main, args=[]) == LinearLRConfig()
+        assert "_target" not in get_helptext_with_checks(LinearLRConfig)
+except ImportError:
+    # We can't install PyTorch in Python 3.13.
+    import sys
+
+    assert sys.version_info >= (3, 13)

tests/test_py311_generated/test_new_style_annotations_min_py39_generated.py

@@ -1,7 +1,8 @@
 import dataclasses
-from typing import Any, Literal, Optional
+from typing import Any, Literal, Optional, Type
 
 import pytest
+from helptext_utils import get_helptext_with_checks
 
 import tyro
 
@@ -67,3 +68,33 @@ def main(
 def test_tuple_direct() -> None:
     assert tyro.cli(tuple[int, ...], args="1 2".split(" ")) == (1, 2)  # type: ignore
     assert tyro.cli(tuple[int, int], args="1 2".split(" ")) == (1, 2)  # type: ignore
+
+
+try:
+    from torch.optim.lr_scheduler import LinearLR, LRScheduler
+
+    def test_type_with_init_false() -> None:
+        """https://github.com/brentyi/tyro/issues/235"""
+
+        @dataclasses.dataclass(frozen=True)
+        class LinearLRConfig:
+            _target: type[LRScheduler] = dataclasses.field(
+                init=False, default_factory=lambda: LinearLR
+            )
+            _target2: Type[LRScheduler] = dataclasses.field(
+                init=False, default_factory=lambda: LinearLR
+            )
+            start_factor: float = 1.0 / 3
+            end_factor: float = 1.0
+            total_iters: Optional[int] = None
+
+        def main(config: LinearLRConfig) -> LinearLRConfig:
+            return config
+
+        assert tyro.cli(main, args=[]) == LinearLRConfig()
+        assert "_target" not in get_helptext_with_checks(LinearLRConfig)
+except ImportError:
+    # We can't install PyTorch in Python 3.13.
+    import sys
+
+    assert sys.version_info >= (3, 13)