`y` escape because the println use interface{} as its parameter, golang
can't know in compiling time what this parameter could be use (to be copy
to global or send to other goroutine). so it is the interface self make
golang hard to keep variable in stack
On Wednesday, June 2, 2021 at 1:30:49 AM UTC+8 ren...@ix.netcom.com wrote:
> Whenever you take the address of something the compiler is going to have a
> hard time with escape analysis due to aliasing. Especially with a complex
> function like println with varadic args.
>
> On Jun 1, 2021, at 11:55 AM, 'Axel Wagner' via golang-nuts <
> golan...@googlegroups.com> wrote:
>
>
>
> "escape" as in "the compiler's escape analysis decides to put it on the
> heap, instead of the stack". You can compile using `-gcflags=-m` to test
> that yourself.
>
> On Tue, Jun 1, 2021 at 6:39 PM Robert Glonek <rob...@glonek.co.uk> wrote:
>
>> What do you mean by escape? It prints the ptr to y, like the previous
>> prints the ptr to x. Y is the same pointer throughout, as it should be.
>>
>> On Tuesday, 1 June 2021 at 14:51:50 UTC+1 tapi...@gmail.com wrote:
>>
>>>
>>> package main
>>>
>>> func newIntPtr(n int) *int {
>>> return &n
>>> }
>>>
>>> func main() {
>>> x := newIntPtr(3)
>>> y := newIntPtr(5)
>>> c := make(chan bool)
>>> go func() {
>>> *y++
>>> close(c)
>>> }()
>>> <-c
>>> println(*x, *y)
>>> println(&x)
>>> //println(&y) // This line makes y escape.
>>> }
>>>
>>> --
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