Bug: Command-line interface generator exits with success code 0 even when you pass random jibberish in the arguments

[unclechu]

The Problem

Take for instance test.raku:

#! /usr/bin/env raku
use v6.d;

multi MAIN('foo') { say 'foo subcommand handler' }
multi MAIN('bar') { say 'bar subcommand handler' }

sub USAGE {
  print $*USAGE ~ "\n\n" ~ qq:to/USAGE/;
  Some example text
  USAGE
}

When I call ./test.raku --help I get the usage info and the exit code is success (0) which is expected, as I correctly and explicitly requested usage info by --help. But when I call ./test.raku random-text or just ./test.raku I get the same usage info but it exits with success (0) while it should be error non-zero exit code it’s arguments parsing failure.

Expected Behavior

When calling ./foo.raku or ./foo.raku random-jibberish to get a non-zero (error) exit code.

Actual Behavior

I get successful exit code (0).

Steps to Reproduce

1. Save the example from “The Problem” section above to test.raku file and chmod +x test.raku

2. Run this:

   $ ./foo.raku
   Usage:
     ./foo.raku foo
     ./foo.raku bar
   
   Some example text
   $ echo $?
   0

   $ ./foo.raku any-random-text
   Usage:
     ./foo.raku foo
     ./foo.raku bar
   
   Some example text
   $ echo $?
   0

Environment

• Operating system: NixOS 23.11.2936.428544ae95ee (Tapir)
• Compiler version (rakudo -v or raku -v):

  $ rakudo -v
  Welcome to Rakudo™ v2023.08.
  Implementing the Raku® Programming Language v6.d.
  Built on MoarVM version 2023.09.

[ab5tract]

USAGE is the older way to define things. In the code there is a comment mentioning that a deprecated message should be shown but it looks like this has not yet been added.

The newer approach is GENERATE-USAGE(&main, |capture) {...}, which is more flexible but also more complicated. However, it will print to STDERR and exit with status 2 if triggered without --help.

Since USAGE leaves the user in charge of printing -- and doesn't provide access to passed arguments -- there is no way to conditionally divert the erroneous cases to STDERR.

However, at first glance it does seem trivial to at least conditionally set the exit status for USAGE, so I've submitted a PR to do just that.

[ab5tract]

@unclechu This should be fixed as of a4c7d5d. Happy hacking!