// checkInterface checks that the method set of x implements the
// interface itype.
// On success it returns "", on failure, an error message.
//
func checkInterface(i *interpreter, itype *types.Interface, x iface) string {
mset := findMethodSet(i, x.t)
it := itype.Underlying().(*types.Interface)
for i, n := 0, it.NumMethods(); i < n; i++ {
m := it.Method(i)
id := ssa.MakeId(m.Name(), m.Pkg())
if mset[id] == nil {
return fmt.Sprintf("interface conversion: %v is not %v: missing method %v", x.t, itype, id)
}
}
return "" // ok
}
