Golang在struct中使用反射设置nil字符串指针值

reflect.Value.CanSet()falseSet()

package main 

import (
    "fmt" 
    "reflect" 
) 

type Person struct { 
    FirstName *string 
    LastName *string 
} 

func main() { 
    p := Person{} 
    firstName := "Ryan" 
    p.FirstName = &firstName 

    rp := reflect.ValueOf(p) 
    fmt.Println("rp:", rp) 

    for i := 0; i < rp.NumField(); i++ { 
     fmt.Printf("%s: Pointer: %d CanSet: %t\n", rp.Type().Field(i).Name, rp.Field(i).Pointer(), rp.Field(i).Elem().CanSet()) 
    } 

    rp.Field(0).Elem().SetString("Brian") 
    fmt.Println(*p.FirstName) 

    // Yields nil pointer error 
    // rp.Field(1).Elem().SetString("Johnson") 
    // fmt.Println(*p.LastName) 

    fmt.Println(rp.Field(1).Type()) 
    fmt.Println(rp.Field(1).CanSet()) 
    // fmt.Println(rp.Field(1).Elem().Type()) // nil pointer here also 
    fmt.Println(rp.Field(1).Elem().CanSet()) 
}