786 rm extra env vars (#787)

* Exclude version action env var in helptext

When using `default_env=True`, the `action="version"` arguments no longer
gets an unused environment variable in helptext.

* Rm subcommand ARG/ENV help when default_env=True

When using `default_env=True`, subcommands in the help output no longer
show unusable ARG or ENV PREFIX_<subcommand>.

---------
Co-authored-by: Claude <noreply@anthropic.com>

Author: asmacdo

CHANGELOG.rst

@@ -11,6 +11,14 @@ The semantic versioning only considers the public API as described in
 :ref:`api-ref`. Components not mentioned in :ref:`api-ref` or different import
 paths are considered internals and can change in minor and patch releases.
 
+v4.42.1 (unreleased)
+--------------------
+
+Fixed
+^^^^^
+- Prevent extra environment variables in helptext when default_env=True, for
+  version actions and subcommands(`#787
+  <https://github.com/omni-us/jsonargparse/pull/787>`__).
 
 v4.42.0 (2025-10-14)
 --------------------

jsonargparse/_formatters.py

@@ -8,6 +8,8 @@
     Action,
     HelpFormatter,
     _HelpAction,
+    _SubParsersAction,
+    _VersionAction,
 )
 from io import StringIO
 from string import Template
@@ -249,8 +251,11 @@ def _format_action_invocation(self, action: Action) -> str:
             return value
         if not parser.default_env:
             return super()._format_action_invocation(action)
+        # Subcommand choices (individual subcommands in the list) don't get ARG: prefix or ENV: line
+        if isinstance(action, _SubParsersAction._ChoicesPseudoAction):
+            return super()._format_action_invocation(action)
         extr = ""
-        if not isinstance(action, (_ActionHelpClassPath, _ActionPrintConfig, ShtabAction, _HelpAction)):
+        if not isinstance(action, (_ActionHelpClassPath, _ActionPrintConfig, ShtabAction, _HelpAction, _VersionAction)):
             extr += "\n  ENV:   " + get_env_var(self, action)
         return "ARG:   " + super()._format_action_invocation(action) + extr
 

jsonargparse_tests/test_formatters.py

@@ -22,6 +22,14 @@ def test_help_basics(parser):
     assert "APP_HELP" not in help_str
 
 
+def test_help_action_version(parser):
+    parser.add_argument("--version", action="version", version="1.0.0")
+    help_str = get_parser_help(parser)
+    assert "ARG:   --version" in help_str
+    assert "APP_VERSION" not in help_str
+    assert "show program's version number and exit" in help_str
+
+
 def test_help_action_config_file(parser):
     parser.add_argument("-c", "--cfg", help="Config in yaml/json.", action="config")
     help_str = get_parser_help(parser)
@@ -140,6 +148,25 @@ def test_help_default_config_files_with_required(tmp_path, parser):
     assert "from config" in help_str
 
 
+def test_help_subcommands_with_default_env(parser):
+    subcommands = parser.add_subcommands()
+    subparser1 = ArgumentParser()
+    subparser2 = ArgumentParser()
+    subcommands.add_subcommand("greet", subparser1, help="Greet someone")
+    subcommands.add_subcommand("farewell", subparser2, help="Say goodbye")
+    help_str = get_parser_help(parser)
+    # Individual subcommands should NOT have ARG: prefix or ENV: lines
+    assert "ARG:   greet" not in help_str
+    assert "ARG:   farewell" not in help_str
+    assert "ENV:   APP_GREET" not in help_str
+    assert "ENV:   APP_FAREWELL" not in help_str
+    # But the subcommand names and help should still be present
+    assert "greet" in help_str
+    assert "Greet someone" in help_str
+    assert "farewell" in help_str
+    assert "Say goodbye" in help_str
+
+
 def test_format_usage(parser):
     parser.add_argument("--v1")
     with patch.dict(os.environ, {"COLUMNS": "200"}):