passthrough passes through a flag as positional

[dbohdan]

I have found a surprising passthrough behavior in Kong v1.2.1. The following example demonstrates it.

package main

import (
	"encoding/json"
	"fmt"

	"github.com/alecthomas/kong"
)

type cli struct {
	Command string   `arg:"" passthrough:""`
	Args    []string `arg:"" optional:"" name:"args"`
	Timeout float64  `short:"t" default:"0"`
}

func main() {
	var cliConfig cli
	kong.Parse(&cliConfig)

	m, err := json.Marshal(cliConfig)
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Println(string(m))
}

$ ./foo -t 9 ls -la
{"Command":"ls","Args":["-la"],"Timeout":9}
$ ./foo -t 9 -la
{"Command":"-l","Args":["a"],"Timeout":9}

Kong takes the first flag and passes it through as a positional argument. It seems like this should be an error. Instead of -l becoming a positional argument, I expected it to be treated as an unknown flag and flags to only be passed through after a non-flag argument.

Edit: I have just learned about github.com/alecthomas/repr. :-)