x = [] decodes into nil

[dtcaciuc]

The following program works differently between 0.3.1 and 0.4.1:

package main

import (
    "log"
    "reflect"

    "github.com/BurntSushi/toml"
)

func main() {
    blob := `
    x = []
    `
    var d map[string]interface{}
    if _, err := toml.Decode(blob, &d); err != nil {
        log.Fatal(err)
    }

    x := d["x"]
    log.Println(x, reflect.ValueOf(x).IsNil())
}

On 0.3.1,

[] false

On 0.4.1,

[] true

For my use case, this is a problem because I'm subsequently encoding the value into JSON and it writes x = null instead of the expected x = []. It also goes deeper than that, for instance x = [[]] would get JSONed as x = [null].

Is this an intended change? Do you think it would be possible/correct to restore the previous behaviour?

[arp242]

It's not really an intentional change, as far as I can recall.

It's really the encoding/json behaviour that's problematic; it's a long-standing issue. I'll probably fix it eventually, but it might be a while. I'll review and merge PRs though.