On Tue, Apr 21, 2020 at 8:17 AM T L <tapir....@gmail.com> wrote:
>
> And is the runtime.KeepAlive call in the following program essential to keep
> the correctness?
>
> package main
>
> import (
> "fmt"
> "unsafe"
> "reflect"
> "runtime"
> )
>
> func main() {
> a := [6]byte{'G', 'o', 'o', 'g', 'l', 'e'}
> bs := []byte("Golang")
> hdr := (*reflect.SliceHeader)(unsafe.Pointer(&bs))
> hdr.Data = uintptr(unsafe.Pointer(&a))
>
> runtime.KeepAlive(&a) // Is this line essential here?
>
> hdr.Len = 2
> hdr.Cap = len(a)
> fmt.Printf("%s\n", bs) // Go
> bs = bs[:cap(bs)]
> fmt.Printf("%s\n", bs) // Google
> }
I do not think the runtime.KeepAlive is required. Setting the Data
field using a *SliceHeader should keep the value alive.
Ian
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