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      1 // errorcheck -0 -l -d=wb
      2 
      3 // Copyright 2015 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 where write barriers are and are not emitted.
      8 
      9 package p
     10 
     11 import "unsafe"
     12 
     13 func f(x **byte, y *byte) {
     14 	*x = y // ERROR "write barrier"
     15 
     16 	z := y // no barrier
     17 	*x = z // ERROR "write barrier"
     18 }
     19 
     20 func f1(x *[]byte, y []byte) {
     21 	*x = y // ERROR "write barrier"
     22 
     23 	z := y // no barrier
     24 	*x = z // ERROR "write barrier"
     25 }
     26 
     27 func f1a(x *[]byte, y *[]byte) {
     28 	*x = *y // ERROR "write barrier"
     29 
     30 	z := *y // no barrier
     31 	*x = z  // ERROR "write barrier"
     32 }
     33 
     34 func f2(x *interface{}, y interface{}) {
     35 	*x = y // ERROR "write barrier"
     36 
     37 	z := y // no barrier
     38 	*x = z // ERROR "write barrier"
     39 }
     40 
     41 func f2a(x *interface{}, y *interface{}) {
     42 	*x = *y // ERROR "write barrier"
     43 
     44 	z := y // no barrier
     45 	*x = z // ERROR "write barrier"
     46 }
     47 
     48 func f3(x *string, y string) {
     49 	*x = y // ERROR "write barrier"
     50 
     51 	z := y // no barrier
     52 	*x = z // ERROR "write barrier"
     53 }
     54 
     55 func f3a(x *string, y *string) {
     56 	*x = *y // ERROR "write barrier"
     57 
     58 	z := *y // no barrier
     59 	*x = z  // ERROR "write barrier"
     60 }
     61 
     62 func f4(x *[2]string, y [2]string) {
     63 	*x = y // ERROR "write barrier"
     64 
     65 	z := y // no barrier
     66 	*x = z // ERROR "write barrier"
     67 }
     68 
     69 func f4a(x *[2]string, y *[2]string) {
     70 	*x = *y // ERROR "write barrier"
     71 
     72 	z := *y // no barrier
     73 	*x = z  // ERROR "write barrier"
     74 }
     75 
     76 type T struct {
     77 	X *int
     78 	Y int
     79 	M map[int]int
     80 }
     81 
     82 func f5(t, u *T) {
     83 	t.X = &u.Y // ERROR "write barrier"
     84 }
     85 
     86 func f6(t *T) {
     87 	t.M = map[int]int{1: 2} // ERROR "write barrier"
     88 }
     89 
     90 func f7(x, y *int) []*int {
     91 	var z [3]*int
     92 	i := 0
     93 	z[i] = x // ERROR "write barrier"
     94 	i++
     95 	z[i] = y // ERROR "write barrier"
     96 	i++
     97 	return z[:i]
     98 }
     99 
    100 func f9(x *interface{}, v *byte) {
    101 	*x = v // ERROR "write barrier"
    102 }
    103 
    104 func f10(x *byte, f func(interface{})) {
    105 	f(x)
    106 }
    107 
    108 func f11(x *unsafe.Pointer, y unsafe.Pointer) {
    109 	*x = unsafe.Pointer(uintptr(y) + 1) // ERROR "write barrier"
    110 }
    111 
    112 func f12(x []*int, y *int) []*int {
    113 	// write barrier for storing y in x's underlying array
    114 	x = append(x, y) // ERROR "write barrier"
    115 	return x
    116 }
    117 
    118 func f12a(x []int, y int) []int {
    119 	// y not a pointer, so no write barriers in this function
    120 	x = append(x, y)
    121 	return x
    122 }
    123 
    124 func f13(x []int, y *[]int) {
    125 	*y = append(x, 1) // ERROR "write barrier"
    126 }
    127 
    128 func f14(y *[]int) {
    129 	*y = append(*y, 1) // ERROR "write barrier"
    130 }
    131 
    132 type T1 struct {
    133 	X *int
    134 }
    135 
    136 func f15(x []T1, y T1) []T1 {
    137 	return append(x, y) // ERROR "write barrier"
    138 }
    139 
    140 type T8 struct {
    141 	X [8]*int
    142 }
    143 
    144 func f16(x []T8, y T8) []T8 {
    145 	return append(x, y) // ERROR "write barrier"
    146 }
    147