duplicate-arguments-array: false breaks variadic positional arguments

[markus456]

I decided to split off this from the problem originally mentioned in issue #1318 as it seems to have unintended side-effects. I've re-tested this with Yargs 17.0 and the problem remains. Unless I'm missing something obvious, this makes it impossible to use variadic positional arguments with "duplicate-arguments-array": false.

---

This seems to also affect variadic positional arguments:

var yargs = require("yargs")

yargs
    .parserConfiguration({
        "duplicate-arguments-array": false,
    })
    .command(
        "test <name> <key> <value> [extras...]",
        "Test positional arguments",
        function (yargs) {},
        function (argv) {
            console.log(argv.name, argv.key, argv.value, argv.extras)
        }
    )
    .parse()

$ node index.js test name key1 value1 key2 value2
name key1 value1 [ 'value2' ]

Removing "duplicate-arguments-array": false from the parser configuration results in expected output:

$ node index.js test name key1 value1 key2 value2
name key1 value1 [ 'key2', 'value2' ]

Explicitly specifying the type of the variadic argument as array with .positional doesn't seem to affect it. This was with yargs 16.2.0.

Originally posted by @markus456 in #1318 (comment)

[markus456]

Here's an example with options included that shows the problem.

var yargs = require("yargs")

yargs
    .parserConfiguration({
        "duplicate-arguments-array": false,
    })
    .command(
        "test <name> <key> <value> [extras...]",
        "Test positional arguments",
        function (yargs) {},
        function (argv) {
            console.log(argv.name, argv.key, argv.value, argv.extras, argv["test-option"])
        }
    )
    .option("test-option",  {type: "string", describe: "a test option"})
    .parse()

Here's the output with "duplicate-arguments-array": false:

$ node index.js test name key1 value1 key2 value2 --test-option opt1 --test-option opt2
name key1 value1 [ 'value2' ] opt2

And here's without it:

$ node index.js test name key1 value1 key2 value2 --test-option opt1 --test-option opt2
name key1 value1 [ 'key2', 'value2' ] [ 'opt1', 'opt2' ]