Executable subcommand does not preserve end-of-options delimiter before option-like operands

[yminod]

Description

Related PR: #2531

A stand-alone executable subcommand does not preserve the first end-of-options delimiter (--) when Commander dispatches to the child process.

This means an option-like operand after -- can be reparsed by the child command as an option, rather than as a positional argument.

Reproduction

Parent:

const { Command } = require('commander');

new Command()
  .name('parent')
  .command('child', 'run child', {
    executableFile: 'child.js',
  })
  .parse();

Child:

const { Command } = require('commander');

new Command()
  .name('parent child')
  .argument('[input]')
  .action((input) => console.log({ input }))
  .parse();

Run:

node parent.js child -- --not-an-option

Expected

The child command should receive the end-of-options delimiter and treat the following value as an operand:

{ input: '--not-an-option' }

Actual

The child command reports an unknown option:

error: unknown option '--not-an-option'

Notes

Commander already treats the first -- as an end-of-options delimiter for normal parsing, consistent with POSIX Utility Syntax Guideline 10¹. The README also documents -- as ending option processing, with remaining arguments used without being interpreted².

For stand-alone executable subcommands, the README says the executable is responsible for handling its own options, rather than declaring them at the top level³. But in this case the parent consumes the delimiter before spawning the executable, so the child does not receive the same end-of-options boundary from the original command line.

I think the compatible behavior is to keep the existing in-process command behavior unchanged, but restore the first delimiter only when spawning an executable subcommand.

Footnotes

1. https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap12.html#tag_12_02 ↩

2. https://github.com/tj/commander.js/blob/ba6d13ddb4243e5913367734f8c159089ffe7834/Readme.md?plain=1#L200 ↩

3. https://github.com/tj/commander.js/blob/ba6d13ddb4243e5913367734f8c159089ffe7834/Readme.md?plain=1#L703 ↩

[shadowspawn]

I was aware of the behaviour. Often the -- get used when passing through options for another command, which is what is happening here behind the scenes. But ideally the implementation decision to use external subcommands would be transparent.