Make sure we return nil slices as empty slices sometimes

[flyingmutant]

As there is code that can work with a := []int{}, but fail with var a []int.

Can we treat empty slices as having something like len = -1 during generation?

[wfscheper]

The only time I can think of where go will handle those differently is in comparison to nil. For example, the following will only print "a is nil" once:

var a []int
if a == nil {
    fmt.Println("a is nil")  // this will print
}
a = []int{}
if a == nil {
    fmt.Println("a is nil")  // this won't
}

[flyingmutant]

Closing as it looks like there is not a lot of value in this.