cgo C struct field access from Go: underscore or no underscore?

I'm running into a disconnect between the online documentation and the behavior I see in my programs accessing C structs within GO code. go version says I am using:

go version go1.4.2 linux/amd64

According to the GO CGO documentation:

> Within the Go file, C's struct field names that are keywords in Go can be
> accessed by prefixing them with an underscore: if x points at a C struct with
> a field named "type", x._type accesses the field. C struct fields that cannot
> be expressed in Go, such as bit fields or misaligned data, are omitted in the
> Go struct, replaced by appropriate padding to reach the next field or the end
> of the struct.

I had troubles with this, so made a quick sample program to test it out:

package main
// struct rec
// {
//      int    i;
//      double d;
//      char*  s;
// };
import "C"
import "fmt"
func main() {
        s := "hello world"
        r := C.struct_rec{}
        r.i = 9
        r.d = 9.876
        r.s = C.CString(s)
        fmt.Printf("\n\tr.i: %d\n\tr.d: %f\n\tr.s: %s\n", 
                r.i, 
                r.d, 
                C.GoString(r.s))
}

When I use underscores as the docs indicate (eg, substitute r._i for r.i above) I get the following compile error:

> r._i undefined (type C.struct_rec has no field or method _i)

When I don't use underscores it works fine. I tried this with both pointers and non-pointers. The only other idea I can think of is that maybe it's because I allocated the instances in GO rather than C, is that the case??

Thanks for any help!

The answer is in the very quote you have in your question:

>Within the Go file, C's struct field names that are keywords in Go can be accessed by prefixing them with an underscore(…)

i, d, and s are not keywords in Go.