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// run
// This test makes sure that t.s = t.s[0:x] doesn't write
// either the slice pointer or the capacity.
// See issue #14855.
package main
import "fmt"
const N = 1000000
type T struct {
s []int
}
func main() {
done := make(chan struct{})
a := make([]int, N+10)
t := &T{a}
go func() {
for i := 0; i < N; i++ {
t.s = t.s[1:9]
}
done <- struct{}{}
}()
go func() {
for i := 0; i < N; i++ {
t.s = t.s[0:8] // should only write len
}
done <- struct{}{}
}()
<-done
<-done
ok := true
if cap(t.s) != cap(a)-N {
fmt.Printf("wanted cap=%d, got %d\n", cap(a)-N, cap(t.s))
ok = false
}
if &t.s[0] != &a[N] {
fmt.Printf("wanted ptr=%p, got %p\n", &a[N], &t.s[0])
ok = false
}
if !ok {
panic("bad")
}
}
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