const bsrc = `package b; import "a"; type T struct { F interface { a.I } }; var _ = a.T(T{})`

	a := mustTypecheck(asrc, nil, nil)

	conf := Config{Importer: importHelper{pkg: a}}
	mustTypecheck(bsrc, &conf, nil)
}

type importHelper struct {
	pkg      *Package
	fallback Importer
}

func (h importHelper) Import(path string) (*Package, error) {

	const bsrc = `package b; import "a"; type T struct { F interface { a.I } }; var _ = a.T(T{})`

	a := mustTypecheck(asrc, nil, nil)

	conf := Config{Importer: importHelper{pkg: a}}
	mustTypecheck(bsrc, &conf, nil)
}

type importHelper struct {
	pkg      *Package
	fallback Importer
}

func (h importHelper) Import(path string) (*Package, error) {

	src := fmt.Sprintf(`package p; import "unsafe"; type _ unsafe.Pointer /* use unsafe */; func _[P ~[]byte]() { %s }`, src0)

	uses := make(map[*ast.Ident]Object)
	types := make(map[ast.Expr]TypeAndValue)
	mustTypecheck(src, nil, &Info{Uses: uses, Types: types})

	// find called function
	n := 0
	var fun ast.Expr
	for x := range types {
		if call, _ := x.(*ast.CallExpr); call != nil {
			fun = call.Fun
			n++
		}

	src := fmt.Sprintf(`package p; import "unsafe"; type _ unsafe.Pointer /* use unsafe */; func _[P ~[]byte]() { %s }`, src0)

	uses := make(map[*syntax.Name]Object)
	types := make(map[syntax.Expr]TypeAndValue)
	mustTypecheck(src, nil, &Info{Uses: uses, Types: types})

	// find called function
	n := 0
	var fun syntax.Expr
	for x := range types {
		if call, _ := x.(*syntax.CallExpr); call != nil {
			fun = call.Fun
			n++