feat: Show subcommand's help info when passing unrecognized arguments

news/2480.feature.md

@@ -0,0 +1 @@
+Show subcommand's help info when passing unrecognized arguments.

src/pdm/cli/utils.py

@@ -9,6 +9,7 @@
 from collections import ChainMap, OrderedDict
 from concurrent.futures import ThreadPoolExecutor
 from fnmatch import fnmatch
+from gettext import gettext as _
 from json import dumps
 from pathlib import Path
 from typing import (
@@ -152,6 +153,13 @@ def __init__(self, *args: Any, **kwargs: Any) -> None:
         )
         self._optionals.title = "options"
 
+    def parse_known_args(self, args: Any = None, namespace: Any = None) -> Any:
+        args, argv = super().parse_known_args(args, namespace)
+        if argv:
+            msg = _("unrecognized arguments: %s")
+            self.error(msg % " ".join(argv))
+        return args, argv
+
 
 class ErrorArgumentParser(ArgumentParser):
     """A subclass of argparse.ArgumentParser that raises

tests/cli/test_utils.py

@@ -0,0 +1,4 @@
+def test_help_with_unknown_arguments(pdm):
+    result = pdm(["add", "--unknown-args"])
+    assert "Usage: pdm add " in result.stderr
+    assert result.exit_code == 2