`cloup.Argument` and `click.Argument` diverge now that Click 8.5.0 has argument `help`

[kdeldycke]

Bug description

Click 8.5.0 added a help parameter to click.Argument and a Positional arguments help section: pallets/click#3473. That is the feature Cloup has shipped since 0.14.0, and the two implementations now conflicts:

• A plain click.argument(..., help=...) inside a Cloup command loses its description.
• cloup.Argument drops the (DEPRECATED) label.

To Reproduce

import click
import cloup
from click.testing import CliRunner


@cloup.command()
@cloup.argument("input_path", help="Input path")
def a(**kwargs):
    """Case A: cloup.argument in a cloup command."""


@cloup.command()
@click.argument("input_path", help="Input path")
def b(**kwargs):
    """Case B: click.argument(help=...) in a cloup command."""


@cloup.command()
@cloup.argument("old_path", help="Legacy path", deprecated=True, required=False)
def c(**kwargs):
    """Case C: deprecated cloup.argument."""


@click.command()
@click.argument("old_path", help="Legacy path", deprecated=True, required=False)
def d(**kwargs):
    """Case D: deprecated click.argument."""


runner = CliRunner()
for name, cmd in [("A", a), ("B", b), ("C", c), ("D", d)]:
    print("###", name)
    print(runner.invoke(cmd, ["--help"], prog_name="example").output)

### A
Usage: example [OPTIONS] INPUT_PATH

  Case A: cloup.argument in a cloup command.

Positional arguments:
  INPUT_PATH  Input path

### B
Usage: example [OPTIONS] INPUT_PATH

  Case B: click.argument(help=...) in a cloup command.

Positional arguments:
  INPUT_PATH

### C
Usage: example [OPTIONS] [OLD_PATH!]

  Case C: deprecated cloup.argument.

Positional arguments:
  [OLD_PATH!]  Legacy path

### D
Usage: example [OPTIONS] [OLD_PATH!]

  Case D: deprecated click.argument.

Positional arguments:
  [OLD_PATH!]  Legacy path (DEPRECATED)

Expected behavior

Case B renders like case A, and case C carries the (DEPRECATED) label like case D.

[janluke]

There's another difference between Click and Cloup. Both print a "Positional arguments" section if at least 1 argument has help but:

• Cloup includes all arguments in the section, including those with no help
• Click only includes arguments with a help.

I guess the reasoning was that the arguments are already listed in the usage anyway, but I think this is potentially misleading for users.

[kdeldycke]

There's another difference between Click and Cloup. Both print a "Positional arguments" section if at least 1 argument has help but:

• Cloup includes all arguments in the section, including those with no help
• Click only includes arguments with a help.

I guess the reasoning was that the arguments are already listed in the usage anyway, but I think this is potentially misleading for users.

Good catch. I agree with you that this is inconsistent. Especially compared with the way options behave. I will propose a fix upstream.

[kdeldycke]

@janluke just made a proposal fix at pallets/click#3860