Fix: --print_shtab crashing on failure to get signature parameters from one class

CHANGELOG.rst

@@ -19,6 +19,9 @@ Fixed
 ^^^^^
 - Resolving of import paths for some ``torch`` functions not working (`#535
   <https://github.com/omni-us/jsonargparse/pull/535>`__).
+- ``--print_shtab`` crashing on failure to get signature parameters from one
+  class (`lightning#10858 comment
+  <https://github.com/Lightning-AI/pytorch-lightning/discussions/10858#discussioncomment-9846252>`__).
 
 Changed
 ^^^^^^^

jsonargparse/_completions.py

@@ -25,10 +25,6 @@
 )
 from ._util import NoneType, Path, import_object, unique
 
-shtab_shell: ContextVar = ContextVar("shtab_shell")
-shtab_prog: ContextVar = ContextVar("shtab_prog")
-shtab_preambles: ContextVar = ContextVar("shtab_preambles")
-
 
 def handle_completions(parser):
     if find_spec("argcomplete") and "_ARGCOMPLETE" in os.environ:
@@ -76,6 +72,10 @@ def argcomplete_warn_redraw_prompt(prefix, message):
 
 # shtab
 
+shtab_shell: ContextVar = ContextVar("shtab_shell")
+shtab_prog: ContextVar = ContextVar("shtab_prog")
+shtab_preambles: ContextVar = ContextVar("shtab_preambles")
+
 
 class ShtabAction(argparse.Action):
     def __init__(
@@ -236,7 +236,7 @@ def get_typehint_choices(typehint, prefix, parser, skip, choices=None, added_sub
         origin = get_typehint_origin(typehint)
         if origin == Union:
             for subtype in typehint.__args__:
-                if subtype in added_subclasses:
+                if subtype in added_subclasses or subtype is object:
                     continue
                 get_typehint_choices(subtype, prefix, parser, skip, choices, added_subclasses)
         elif ActionTypeHint.is_subclass_typehint(typehint):
@@ -261,8 +261,12 @@ def add_subactions_and_get_subclass_choices(typehint, prefix, parser, skip, adde
     subclasses = defaultdict(list)
     for path in paths:
         choices.append(path)
-        cls = import_object(path)
-        params = get_signature_parameters(cls)
+        try:
+            cls = import_object(path)
+            params = get_signature_parameters(cls, None, parser._logger)
+        except Exception as ex:
+            parser._logger.debug(f"Unable to get signature parameters for '{path}': {ex}")
+            continue
         num_skip = next((s for s in skip if isinstance(s, int)), 0)
         if num_skip > 0:
             params = params[num_skip:]

jsonargparse_tests/test_shtab.py

@@ -13,9 +13,10 @@
 
 from jsonargparse import ArgumentParser
 from jsonargparse._completions import norm_name
+from jsonargparse._parameter_resolvers import get_signature_parameters
 from jsonargparse._typehints import type_to_str
 from jsonargparse.typing import Path_drw, Path_fr
-from jsonargparse_tests.conftest import get_parse_args_stdout
+from jsonargparse_tests.conftest import capture_logs, get_parse_args_stdout
 
 
 @pytest.fixture(autouse=True)
@@ -203,6 +204,22 @@ def __init__(self, p1: int, p3: float):
         pass
 
 
+def test_bash_subclasses_fail_get_perams(parser, logger):
+    def get_params_patch(cls, method, logger):
+        if cls == SubB:
+            raise Exception("test get params failure")
+        return get_signature_parameters(cls, method, logger)
+
+    parser.logger = logger
+    parser.add_argument("--cls", type=Base)
+    with capture_logs(logger) as logs, patch("jsonargparse._completions.get_signature_parameters", get_params_patch):
+        shtab_script = get_shtab_script(parser, "bash")
+    assert "'--cls' '--cls.p1' '--cls.p2'" in shtab_script
+    assert f"'{__name__}.SubB'" in shtab_script
+    assert "'--cls.p3'" not in shtab_script
+    assert "test_shtab.SubB': test get params failure" in logs.getvalue()
+
+
 def test_bash_subclasses_help(parser):
     parser.add_argument("--cls", type=Base)
     shtab_script = get_shtab_script(parser, "bash")