1// Copyright 2011 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package main
6
7import (
8	"./p"
9)
10
11type Exported interface {
12	private()
13}
14
15type Implementation struct{}
16
17func (p *Implementation) private() {}
18
19
20func main() {
21	// nothing unusual here
22	var x Exported
23	x = new(Implementation)
24	x.private()  //  main.Implementation.private()
25
26	// same here - should be and is legal
27	var px p.Exported
28	px = p.X
29
30	// this assignment is correctly illegal:
31	//	px.private undefined (cannot refer to unexported field or method private)
32	// px.private()
33
34	// this assignment is correctly illegal:
35	//	*Implementation does not implement p.Exported (missing p.private method)
36	// px = new(Implementation)
37
38	// this assignment is correctly illegal:
39	//	p.Exported does not implement Exported (missing private method)
40	// x = px
41
42	// this assignment unexpectedly compiles and then executes
43	defer func() {
44		recover()
45	}()
46	x = px.(Exported)
47
48	println("should not get this far")
49
50	// this is a legitimate call, but because of the previous assignment,
51	// it invokes the method private in p!
52	x.private()  // p.Implementation.private()
53}
54