fix(config): forward token kwarg to get_config_dict in PreTrainedConfig.from_pretrained (#50081)

`token` is an explicit parameter of `PreTrainedConfig.from_pretrained` but was
never added to `kwargs` before calling `get_config_dict`. This caused it to
arrive as `None` in `cached_files`, silently dropping the caller's token.

Consequence: loading from private or gated repos using `token=` as a kwarg
only worked if `HF_TOKEN` was also set as an env var. In clean environments
(e.g. CI pipelines that pass the token explicitly without `hf auth login`),
it would fail with a 401 / RepositoryNotFoundError.

All other `from_pretrained` entry points (tokenizers, processors, feature
extractors) already forward `token` correctly. This was specific to the config
loading path.

Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>

Author: ydshieh

src/transformers/configuration_utils.py

@@ -877,6 +877,7 @@ def from_pretrained(
         kwargs["cache_dir"] = cache_dir
         kwargs["force_download"] = force_download
         kwargs["local_files_only"] = local_files_only
+        kwargs["token"] = token
         kwargs["revision"] = revision
 
         config_dict, kwargs = cls.get_config_dict(pretrained_model_name_or_path, **kwargs)

tests/utils/test_configuration_utils.py

@@ -476,6 +476,33 @@ def __init__(
         self.assertIsInstance(new_config_instance.nan, float)
 
 
+class ConfigTokenPropagationTest(unittest.TestCase):
+    def test_token_kwarg_forwarded_to_get_config_dict(self):
+        """
+        Regression test: `token` is an explicit parameter of `PreTrainedConfig.from_pretrained`
+        but was not forwarded into `kwargs` before calling `get_config_dict`, so it arrived as
+        `None` in `cached_files`. This broke loading from private/gated repos when `token=` was
+        passed as a kwarg and `HF_TOKEN` env var was not set.
+        """
+        captured = {}
+
+        def fake_get_config_dict(cls, pretrained_model_name_or_path, **kwargs):
+            captured["token"] = kwargs.get("token")
+            raise OSError("stop")  # abort early, we only care about kwargs
+
+        with mock.patch.object(BertConfig, "get_config_dict", classmethod(fake_get_config_dict)):
+            try:
+                BertConfig.from_pretrained("dummy-repo", token="my-secret-token")
+            except OSError:
+                pass
+
+        self.assertEqual(
+            captured.get("token"),
+            "my-secret-token",
+            "token kwarg was not forwarded to get_config_dict",
+        )
+
+
 class ConfigSubclassKwOnlyTest(unittest.TestCase):
     """Test that config subclasses with non-default fields following parent default fields
     no longer raise TypeError (fixed by kw_only=True in __init_subclass__). Regression