1// run
2
3// Copyright 2014 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
7package main
8
9import "unsafe"
10
11var (
12	hello = "hello"
13	bytes = []byte{1, 2, 3, 4, 5}
14	ints  = []int32{1, 2, 3, 4, 5}
15
16	five = 5
17
18	ok = true
19)
20
21func notOK() {
22	if ok {
23		println("BUG:")
24		ok = false
25	}
26}
27
28func checkString(desc, s string) {
29	p1 := *(*uintptr)(unsafe.Pointer(&s))
30	p2 := *(*uintptr)(unsafe.Pointer(&hello))
31	if p1-p2 >= 5 {
32		notOK()
33		println("string", desc, "has invalid base")
34	}
35}
36
37func checkBytes(desc string, s []byte) {
38	p1 := *(*uintptr)(unsafe.Pointer(&s))
39	p2 := *(*uintptr)(unsafe.Pointer(&bytes))
40	if p1-p2 >= 5 {
41		println("byte slice", desc, "has invalid base")
42	}
43}
44
45func checkInts(desc string, s []int32) {
46	p1 := *(*uintptr)(unsafe.Pointer(&s))
47	p2 := *(*uintptr)(unsafe.Pointer(&ints))
48	if p1-p2 >= 5*4 {
49		println("int slice", desc, "has invalid base")
50	}
51}
52
53func main() {
54	{
55		x := hello
56		checkString("x", x)
57		checkString("x[5:]", x[5:])
58		checkString("x[five:]", x[five:])
59		checkString("x[5:five]", x[5:five])
60		checkString("x[five:5]", x[five:5])
61		checkString("x[five:five]", x[five:five])
62		checkString("x[1:][2:][2:]", x[1:][2:][2:])
63		y := x[4:]
64		checkString("y[1:]", y[1:])
65	}
66	{
67		x := bytes
68		checkBytes("x", x)
69		checkBytes("x[5:]", x[5:])
70		checkBytes("x[five:]", x[five:])
71		checkBytes("x[5:five]", x[5:five])
72		checkBytes("x[five:5]", x[five:5])
73		checkBytes("x[five:five]", x[five:five])
74		checkBytes("x[1:][2:][2:]", x[1:][2:][2:])
75		y := x[4:]
76		checkBytes("y[1:]", y[1:])
77	}
78	{
79		x := ints
80		checkInts("x", x)
81		checkInts("x[5:]", x[5:])
82		checkInts("x[five:]", x[five:])
83		checkInts("x[5:five]", x[5:five])
84		checkInts("x[five:5]", x[five:5])
85		checkInts("x[five:five]", x[five:five])
86		checkInts("x[1:][2:][2:]", x[1:][2:][2:])
87		y := x[4:]
88		checkInts("y[1:]", y[1:])
89	}
90}
91