proposal: unsafe: add a func to convert bool type to int

[ahfuzhang]

Proposal Details

sometimes I don't want to use if when search a table.
So if we can convert a bool value to int, then we can reduce if clause .

For example:

var aTableToSearch = []int64{xxxx}
var a int = 1234

func getValueFromTable(index int) int64{
     if a>1000{
          return aTableToSearch[0]
     }
     return aTableToSearch[index]
}

We can change another way if we can convert bool to int:

var aTableToSearch = []int64{xxxx}
var a int = 1234

func getValueFromTable(index int) int64{
     return aTableToSearch[index*BoolToInt(!(a>1000))]
}

func BoolToInt(b bool) int{
    return int(*(*uint8)(unsafe.Pointer(&b)))  // this way is slow, use assemly
}

[ALTree]

This is a dup of #64825, closing here in favour of the older thread.