shtab support literal and fix positionals (#693)

Author: mauvilsa

CHANGELOG.rst

@@ -15,6 +15,11 @@ paths are considered internals and can change in minor and patch releases.
 v4.38.0 (2025-02-??)
 --------------------
 
+Added
+^^^^^
+- Support ``shtab`` completion of ``Literal`` types (`#693
+  <https://github.com/omni-us/jsonargparse/pull/693>`__).
+
 Changed
 ^^^^^^^
 - ``validate`` now checks values before required so that errors related to wrong
@@ -30,6 +35,9 @@ Fixed
 - Help incorrectly showing environment variable name for ``--print_shtab``.
 - ``add_argument`` raises error when type is assigned with ``action=None``
   (`#687 <https://github.com/omni-us/jsonargparse/issues/687>`__).
+- ``shtab`` failing when parser has positional arguments (`#693
+  <https://github.com/omni-us/jsonargparse/pull/693>`__).
+
 
 v4.37.0 (2025-02-14)
 --------------------

jsonargparse/_completions.py

@@ -9,7 +9,7 @@
 from enum import Enum
 from importlib.util import find_spec
 from subprocess import PIPE, Popen
-from typing import List, Union
+from typing import List, Literal, Union
 
 from ._actions import ActionConfigFile, _ActionConfigLoad, _ActionHelpClassPath, remove_actions
 from ._parameter_resolvers import get_signature_parameters
@@ -162,7 +162,8 @@ def shtab_prepare_action(action, parser) -> None:
     choices = None
     if isinstance(action, ActionTypeHint):
         skip = getattr(action, "sub_add_kwargs", {}).get("skip", set())
-        choices = get_typehint_choices(action._typehint, action.option_strings[0], parser, skip)
+        prefix = action.option_strings[0] if action.option_strings else None
+        choices = get_typehint_choices(action._typehint, prefix, parser, skip)
         if shtab_shell.get() == "bash":
             message = f"Expected type: {type_to_str(action._typehint)}"
             add_bash_typehint_completion(parser, action, message, choices)
@@ -232,7 +233,9 @@ def get_typehint_choices(typehint, prefix, parser, skip, choices=None, added_sub
         choices.extend(list(typehint.__members__))
     else:
         origin = get_typehint_origin(typehint)
-        if origin == Union:
+        if origin == Literal:
+            choices.extend([str(a) for a in typehint.__args__ if isinstance(a, (str, int, float))])
+        elif origin == Union:
             for subtype in typehint.__args__:
                 if subtype in added_subclasses or subtype is object:
                     continue
@@ -273,18 +276,19 @@ def add_subactions_and_get_subclass_choices(typehint, prefix, parser, skip, adde
                 init_args[param.name].append(param.annotation)
                 subclasses[param.name].append(path.rsplit(".", 1)[-1])
 
-    for name, subtypes in init_args.items():
-        option_string = f"{prefix}.{name}"
-        if option_string not in parser._option_string_actions:
-            action = parser.add_argument(option_string)
-            for subtype in unique(subtypes):
-                subchoices = get_typehint_choices(subtype, option_string, parser, skip, None, added_subclasses)
-                if shtab_shell.get() == "bash":
-                    message = f"Expected type: {type_to_str(subtype)}; "
-                    message += f"Accepted by subclasses: {', '.join(subclasses[name])}"
-                    add_bash_typehint_completion(parser, action, message, subchoices)
-                elif subchoices:
-                    action.choices = subchoices
+    if prefix is not None:
+        for name, subtypes in init_args.items():
+            option_string = f"{prefix}.{name}"
+            if option_string not in parser._option_string_actions:
+                action = parser.add_argument(option_string)
+                for subtype in unique(subtypes):
+                    subchoices = get_typehint_choices(subtype, option_string, parser, skip, None, added_subclasses)
+                    if shtab_shell.get() == "bash":
+                        message = f"Expected type: {type_to_str(subtype)}; "
+                        message += f"Accepted by subclasses: {', '.join(subclasses[name])}"
+                        add_bash_typehint_completion(parser, action, message, subchoices)
+                    elif subchoices:
+                        action.choices = subchoices
 
     return choices
 

jsonargparse_tests/test_shtab.py

@@ -5,7 +5,7 @@
 from importlib.util import find_spec
 from os import PathLike
 from pathlib import Path
-from typing import Any, Callable, Optional, Union
+from typing import Any, Callable, Literal, Optional, Union
 from unittest.mock import patch
 
 import pytest
@@ -146,6 +146,19 @@ def test_bash_optional_enum(parser, subtests):
     )
 
 
+def test_bash_literal(parser, subtests):
+    typehint = Optional[Literal["one", "two"]]
+    parser.add_argument("--literal", type=typehint)
+    assert_bash_typehint_completions(
+        subtests,
+        parser,
+        [
+            ("literal", typehint, "", ["one", "two", "null"], "3/3"),
+            ("literal", typehint, "t", ["two"], "1/3"),
+        ],
+    )
+
+
 def test_bash_union(parser, subtests):
     typehint = Optional[Union[bool, AXEnum]]
     parser.add_argument("--union", type=typehint)
@@ -159,6 +172,19 @@ def test_bash_union(parser, subtests):
     )
 
 
+def test_bash_positional(parser, subtests):
+    typehint = Literal["Alice", "Bob"]
+    parser.add_argument("name", type=typehint)
+    assert_bash_typehint_completions(
+        subtests,
+        parser,
+        [
+            ("name", typehint, "", ["Alice", "Bob"], "2/2"),
+            ("name", typehint, "Al", ["Alice"], "1/2"),
+        ],
+    )
+
+
 def test_bash_config(parser):
     parser.add_argument("--cfg", action="config")
     shtab_script = get_shtab_script(parser, "bash")