1// run
2
3// Copyright 2016 The Go Authors. All rights reserved.
4// Use of this source code is governed by a BSD-style
5// license that can be found in the LICENSE file.
6
7// Test that an interface conversion error panics with an "interface
8// conversion" run-time error. It was (incorrectly) panicking with a
9// "nil pointer dereference."
10
11package main
12
13import (
14	"fmt"
15	"runtime"
16	"strings"
17)
18
19type I interface {
20	Get() int
21}
22
23func main() {
24	defer func() {
25		r := recover()
26		if r == nil {
27			panic("expected panic")
28		}
29		re, ok := r.(runtime.Error)
30		if !ok {
31			panic(fmt.Sprintf("got %T, expected runtime.Error", r))
32		}
33		if !strings.Contains(re.Error(), "interface conversion") {
34			panic(fmt.Sprintf("got %q, expected interface conversion error", re.Error()))
35		}
36	}()
37	e := (interface{})(0)
38	if _, ok := e.(I); ok {
39		panic("unexpected interface conversion success")
40	}
41	fmt.Println(e.(I))
42	panic("unexpected interface conversion success")
43}
44