package main

import "fmt"
import "reflect"

type (
    T1 struct{ X int }
    T2 struct{ T1 }
    T3 struct{ T2; Z int }
    T4 struct{ T2; Z int }
    T5 struct {
        T3
        T4
        Y int
    }
)

func main() {
    v := reflect.ValueOf(T5{})
    fmt.Println("X", v.FieldByName("X"))
    fmt.Println("Y", v.FieldByName("Y"))
    fmt.Println("Z", v.FieldByName("Z"))
}

should print:

X <invalid Value>
Y <int Value>
Z <invalid Value>

However, using gc, at tip, it prints:

<int Value>
<int Value>
<invalid Value>

play.golang.org produces the correct result ( http://play.golang.org/p/rBGZEubaNy ), as
does gccgo.

I suspect that gccgo and the playground use an older version of reflect.