Embedded struct with prefix does not work well with kong.ConfigFlag

[midnightexigent]

The following examples:

package main

import (
        "fmt"

        "github.com/alecthomas/kong"
)

func main() {
        var cli1 struct {
                Module struct {
                        ConfigFile kong.ConfigFlag
                        Val1       int
                        Val2       int
                } `embed:"" prefix:"module."`
                // other params
        }

        kong.Parse(&cli1, kong.Configuration(kong.JSON))

        fmt.Println(cli1)

        var cli2 struct {
                Module struct {
                        ConfigFile kong.ConfigFlag
                        Module     struct {
                                Val1 int
                                Val2 int
                        } `embed:"" prefix:"module."`
                } `embed:"" prefix:"module."`
                // other params
        }
        kong.Parse(&cli2, kong.Configuration(kong.JSON))

        fmt.Println(cli2)
}

With a config file that looks like

{
    "val1": 1,
    "val2": 2
}

When run with the command
go run main.go --module.config-file ./config.json

Will output:

{{./config.json 0 0}}
{{./config.json {0 0}}}

Am I doing something wrong ? Or this is a bug/side effect ?

[alecthomas]

I think you might be expecting Module.ConfigFile to only load config for Module, but that's not how it works. Config file keys are global in all existing configuration loaders, not scoped to sub-structures, so the correct keys would be module.val1 etc.

Because they're global it also doesn't help to have ConfigFile underneath Module.

I think you could probably achieve what you want by writing your own custom resolver.