1 // run 2 3 // Copyright 2017 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 // Issue 21687: cmd/compile evaluates x twice in "x op= y", which was 8 // detectable if evaluating y affects x. 9 10 package main 11 12 func ptrs() (int, int) { 13 one := 1 14 two := 2 15 16 x := &one 17 *x += func() int { 18 x = &two 19 return 0 20 }() 21 22 return one, two 23 } 24 25 func slices() (int, int) { 26 one := []int{1} 27 two := []int{2} 28 29 x := one 30 x[0] += func() int { 31 x = two 32 return 0 33 }() 34 35 return one[0], two[0] 36 } 37 38 func maps() (int, int) { 39 one := map[int]int{0: 1} 40 two := map[int]int{0: 2} 41 42 x := one 43 x[0] += func() int { 44 x = two 45 return 0 46 }() 47 48 return one[0], two[0] 49 } 50 51 var tests = [...]func() (int, int){ 52 ptrs, 53 slices, 54 maps, 55 } 56 57 func main() { 58 bad := 0 59 for i, f := range tests { 60 if a, b := f(); a+b != 3 { 61 println(i, a, b) 62 bad++ 63 } 64 } 65 if bad != 0 { 66 panic(bad) 67 } 68 } 69
