Fix validation of defaults getting stuck for path with stdin default

CHANGELOG.rst

@@ -28,6 +28,8 @@ Fixed
   <https://github.com/omni-us/jsonargparse/pull/833>`__).
 - Targets of links applied on parse not being instantiated (`#834
   <https://github.com/omni-us/jsonargparse/pull/834>`__).
+- Validation of defaults getting stuck for path with ``-`` (stdin) default
+  (`#837 <https://github.com/omni-us/jsonargparse/pull/837>`__).
 
 
 v4.45.0 (2025-12-26)

jsonargparse/_common.py

@@ -59,6 +59,7 @@ def __call__(self, class_type: type[ClassType], *args, **kwargs) -> ClassType:
 defaults_cache: ContextVar[Optional[Namespace]] = ContextVar("defaults_cache", default=None)
 lenient_check: ContextVar[Union[bool, str]] = ContextVar("lenient_check", default=False)
 parsing_defaults: ContextVar[bool] = ContextVar("parsing_defaults", default=False)
+validating_defaults: ContextVar[bool] = ContextVar("validating_defaults", default=False)
 load_value_mode: ContextVar[Optional[str]] = ContextVar("load_value_mode", default=None)
 class_instantiators: ContextVar[Optional[InstantiatorsDictType]] = ContextVar("class_instantiators", default=None)
 nested_links: ContextVar[list[dict]] = ContextVar("nested_links", default=[])
@@ -72,6 +73,7 @@ def __call__(self, class_type: type[ClassType], *args, **kwargs) -> ClassType:
     "defaults_cache": defaults_cache,
     "lenient_check": lenient_check,
     "parsing_defaults": parsing_defaults,
+    "validating_defaults": validating_defaults,
     "load_value_mode": load_value_mode,
     "class_instantiators": class_instantiators,
     "nested_links": nested_links,
@@ -207,7 +209,7 @@ def validate_default(container: ActionsContainer, action: argparse.Action):
 
         if isinstance(container, ArgumentGroup):
             container = container.parser  # type: ignore[assignment]
-        with parser_context(parent_parser=container):
+        with parser_context(parent_parser=container, validating_defaults=True):
             default = action.default
             action.default = None
             action.default = action._check_type_(default)  # type: ignore[attr-defined]

jsonargparse/_core.py

@@ -1037,7 +1037,8 @@ def get_defaults(self, skip_validation: bool = False, **kwargs) -> Namespace:
                 cfg["__default_config__"] = default_config_file
             self._logger.debug("Parsed default configuration from path: %s", default_config_file)
 
-        ActionTypeHint.add_sub_defaults(self, cfg)
+        with parser_context(validating_defaults=True):
+            ActionTypeHint.add_sub_defaults(self, cfg)
 
         return cfg
 

jsonargparse/_typehints.py

@@ -59,6 +59,7 @@
     nested_links,
     parent_parser,
     parser_context,
+    validating_defaults,
 )
 from ._loaders_dumpers import (
     get_loader_exceptions,
@@ -897,6 +898,8 @@ def adapt_typehints(
             prev_val = prev_val + [None] * (len(val) - len(prev_val) if val_is_list else 1)
         list_path = None
         if enable_path and type(val) is str:
+            if validating_defaults.get():
+                return val
             with suppress(TypeError):
                 from ._optionals import _get_config_read_mode
 

jsonargparse_tests/conftest.py

@@ -193,6 +193,15 @@ def logger() -> logging.Logger:
     return logger
 
 
+def patch_parsing_settings(fn):
+    @wraps(fn)
+    def _patch_parsing_settings(*args, **kwargs):
+        with patch.dict("jsonargparse._common.parsing_settings"):
+            return fn(*args, **kwargs)
+
+    return _patch_parsing_settings
+
+
 @contextmanager
 def capture_logs(logger: logging.Logger) -> Iterator[StringIO]:
     with ExitStack() as stack:

jsonargparse_tests/test_parsing_settings.py

@@ -12,7 +12,7 @@
 
 
 @pytest.fixture(autouse=True)
-def patch_parsing_settings():
+def auto_patch_parsing_settings():
     with patch.dict("jsonargparse._common.parsing_settings"):
         yield
 

jsonargparse_tests/test_paths.py

@@ -12,7 +12,7 @@
 
 import pytest
 
-from jsonargparse import ArgumentError, Namespace
+from jsonargparse import ArgumentError, Namespace, set_parsing_settings
 from jsonargparse._optionals import fsspec_support, url_support
 from jsonargparse._paths import _current_path_dir, _parse_url
 from jsonargparse.typing import Path, Path_drw, Path_fc, Path_fr, path_type
@@ -21,6 +21,7 @@
     is_posix,
     json_or_yaml_dump,
     json_or_yaml_load,
+    patch_parsing_settings,
     responses_activate,
     responses_available,
     skip_if_fsspec_unavailable,
@@ -524,6 +525,16 @@
     assert json_or_yaml_load(parser.dump(cfg)) == {"paths": ["path1", "path2"]}
 
 
+def test_path_fr_default_stdin(parser):
+    parser.add_argument("--path", type=Path_fr, default="-")
+
+    defaults = parser.get_defaults()
+    assert defaults.path == Path_fr("-")
+
+    defaults = parser.parse_args([])
+    assert defaults.path == Path_fr("-")
+
+
 # enable_path tests
 
 
@@ -622,7 +633,10 @@
         ctx.match("Expected a path but no-such-file either not accessible or invalid")
 
 
-def test_enable_path_list_path_fr_default_stdin(parser, tmp_cwd, mock_stdin, subtests):
+@pytest.mark.parametrize("validate_defaults", [False, True])
+@patch_parsing_settings
+def test_enable_path_list_path_fr_default_stdin(parser, tmp_cwd, validate_defaults, mock_stdin, subtests):
+    set_parsing_settings(validate_defaults=validate_defaults)
     (tmp_cwd / "file1").touch()
     (tmp_cwd / "file2").touch()
 
@@ -633,6 +647,10 @@
         default="-",
     )
 
+    with subtests.test("defaults"):
+        defaults = parser.get_defaults()
+        assert defaults.list == "-"
+
     with subtests.test("without args"):
         with mock_stdin("file1\nfile2\n"):
             cfg = parser.parse_args([])