What is the correct way to convert Go func to uintptr?

In the Go language, converting a `func` type to a `uintptr` type is a common operation, but the correct method is not to convert directly, because this may leading to some potential problems. The correct method is to use the `Pointer` function in the `unsafe` package to convert the `func` type value to the `unsafe.Pointer` type first, and then convert it to the `uintptr` type. This ensures the safety of type conversion and avoids unpredictable errors. Although this method requires the use of the `unsafe` package, under the right circumstances, it can effectively solve the problem of converting `Go func` to `uintptr`.

Question content

I need to pass and receive go functions in go code.

Due to the way system calls work in the go language, the type used for "passage" is uintptr.

I have no choice but uintptr since syscall.syscalln accepts and returns this type.

What is the correct way to convert go func to uintptr?

I tried using it in the sandbox but I can't simply convert it.

package main

import (
    "fmt"
    "unsafe"
)

func main() {
    var f MyFunc = SumInt
    fmt.Println(f(1, 2))
    test(uintptr(f))                 // Cannot convert an expression of the type 'MyFunc' to the type 'uintptr'
    test(uintptr(unsafe.Pointer(f))) // Cannot convert an expression of the type 'MyFunc' to the type 'unsafe.Pointer'
}

type MyFunc func(a int, b int) (sum int)

func SumInt(a, b int) int {
    return a + b
}

func test(x uintptr) {
    var xf MyFunc
    xf = MyFunc(x)                 // Cannot convert an expression of the type 'uintptr' to the type 'MyFunc'
    xf = MyFunc(unsafe.Pointer(x)) // Cannot convert an expression of the type 'unsafe.Pointer' to the type 'MyFunc'
    fmt.Println(xf(1, 2))
}

I searched on the internet but this information cannot be seen directly in google.

Thanks.

Solution

I found a solution! I need to pass a function pointer.

package main

import (
    "fmt"
    "unsafe"
)

func main() {
    var f myfunc = sumint
    fmt.println(f(1, 2))
    test(uintptr(unsafe.pointer(&f)))
}

type myfunc func(a int, b int) (sum int)

func sumint(a, b int) int {
    return a + b
}

func test(x uintptr) {
    var xfp *myfunc
    xfp = (*myfunc)(unsafe.pointer(x))

    var xf myfunc
    xf = *xfp
    fmt.println(xf(1, 2))
}

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Process finished with the exit code 0

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