Test of implicit field selections in method calls.

The two level wrapping T -> unexported -> U is required
to exercise the implicit selections exportedness check;
with only a single level, the receiver declaration in
"func (unexported) F()" would fail the earlier
unexportedness check.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

import "testdata/b"

func _(x b.T) {
	x.F() //@ inline(re"F", re"in x.F, implicit reference to unexported field .unexported cannot be made explicit")
}

-- b/b.go --
package b

type T struct { unexported }
type unexported struct { U }
type U struct{}
func (U) F() {}