How to safely convert a pointer to *unsafe.Pointer

[ju...@sqreen.io]

Hello,

I would like to make sure that the following line of Go is a defined behavior:

 addr := (*unsafe.Pointer)((unsafe.Pointer)(&ptr))

I use it to perform atomic loads and stores to addr such as in this simple example: https://play.golang.org/p/DpDrRvTYMG8

It allows me not to use atomic.Value which performs two atomic operations and possible disable preemption (https://golang.org/src/sync/atomic/value.go?s=1233:1269#L35).

Thanks for your help,

Julio

[Ian Lance Taylor]

Yes, that operation is defined. As documented at
https://golang.org/pkg/unsafe, you can use unsafe.Pointer to convert
from a pointer to one type to a pointer to a different type.

Ian