hi, This is a variation for a previous topic <https://groups.google.com/g/golang-nuts/c/h75BwBsz4YA/m/FLBIjgFBBQAJ>, but since there isn't a clear solution, I thought I would ask if anyone can think of a work around.
I've been interacting a lot with C++ libraries from Go, and one of the commonly returned types is an abls::StatusOr <https://abseil.io/docs/cpp/guides/status>, for which I created a simple C wrapper that casts the error and value to a `char *` and `void *` respectively (dropping the type information in between C++ and Go). In Go I want to return the type information, so I defined a small generic function: // PointerOrError converts a StatusOr structure to either a pointer to T with the data // or the Status converted to an error message and then freed. func PointerOrError[T any](s C.StatusOr) (*T, error) { ptr, err := UnsafePointerOrError(s) // returns unsafe.Pointer, error if err != nil { return nil, err } return (*T)(ptr), nil } Now this doesn't work for my forward declared C++ types (most of them are just aliases to C++ objects) -- Go complaints with: `cannot use incomplete (or unallocatable) type as a type argument`, because `T` is incomplete indeed. But ... I will never instantiate `T`, I only care about `*T`, which is not incomplete. But there isn't a way to say a generics attribute is a pointer. So if I use the following: func PointerOrError2[T any](s C.StatusOr) (t T, err error) { var ptr unsafe.Pointer ptr, err = UnsafePointerOrError(s) // <-- unsafe.Pointer, error if err != nil { return } t = (T)(ptr) return } And instantiate it with a `PointerOrError2[*MyType](statusOr)` for instance, I get, as expected: cannot convert ptr (variable of type unsafe.Pointer) to type T Any suggestions to make this work ? I could probably craft something using the `reflect` package, but I was hoping for a smart (and likely faster?) generics solution. cheers Jan -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/bd1e1a06-e10b-460e-b04a-3ea06b3be06fn%40googlegroups.com.
