1 // run 2 3 // This test makes sure that t.s = t.s[0:x] doesn't write 4 // either the slice pointer or the capacity. 5 // See issue #14855. 6 7 package main 8 9 import "fmt" 10 11 const N = 1000000 12 13 type T struct { 14 s []int 15 } 16 17 func main() { 18 done := make(chan struct{}) 19 a := make([]int, N+10) 20 21 t := &T{a} 22 23 go func() { 24 for i := 0; i < N; i++ { 25 t.s = t.s[1:9] 26 } 27 done <- struct{}{} 28 }() 29 go func() { 30 for i := 0; i < N; i++ { 31 t.s = t.s[0:8] // should only write len 32 } 33 done <- struct{}{} 34 }() 35 <-done 36 <-done 37 38 ok := true 39 if cap(t.s) != cap(a)-N { 40 fmt.Printf("wanted cap=%d, got %d\n", cap(a)-N, cap(t.s)) 41 ok = false 42 } 43 if &t.s[0] != &a[N] { 44 fmt.Printf("wanted ptr=%p, got %p\n", &a[N], &t.s[0]) 45 ok = false 46 } 47 if !ok { 48 panic("bad") 49 } 50 } 51
