You might be interested in https://github.com/golang/go/issues/61372
On Mon, Aug 14, 2023 at 3:52 PM Diego Augusto Molina <
diegoaugustomol...@gmail.com> wrote:
> Hi, thank you for reading. Whenever I need to use a zero value for a
> generic type in a func I do something like the following:
>
> <code>
> func SetZero[T any](pt *T) T {
> var zeroT T
> *pt = zeroT
> }
> </code>
>
> That's all good, but I wonder how, if possible, it could be proved to the
> compiler that zeroT is the zero value for T. That would be to enable
> memclr optimization when bulk setting slice or array values to the zero
> value of their element type. Currently, as of 1.21, this only works when
> the src is a constant holding the zero value of the type. I also tried with
> something like *new(T), and it doesn't work either. But proving that the
> expression *new(T) in the src is the zero value for the type could
> potentially be easier than checking back if a certain variable (e.g. zeroT
> in the example) hasn't yet been reassigned or initialized to a non-zero
> value.
> Also, as there's no guarantee of what would T could hold, it could use
> memclrHasPointers if that makes sense, which seems like a fare tradeoff
> at least for now if we want to play with slices with generic element type.
> For reference, this is the code I'm trying:
>
> <code>
> package main
> // file generic_slice_element_type_memclr.go
>
> func clear[T any](s []T) {
> for i := range s {
> s[i] = *new(T)
> }
> }
>
> func main() {
> clear([]int{1, 2, 3})
> }
> </code>
>
> And I'm compiling it with:
>
> <code>
> $ go version
> go version go1.21.0 darwin/amd64
> $ go tool compile -S generic_slice_element_type_memclr.go
> ...
> </code>
>
> Kind regards.
>
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