type eface struct {
    _type *_type
    data  unsafe.Pointer
}
type _type struct {
    size       uintptr // type size
    ptrdata    uintptr // size of memory prefix holding all pointers
    hash       uint32  // hash of type; avoids computation in hash tables
    tflag      tflag   // extra type information flags
    align      uint8   // alignment of variable with this type
    fieldalign uint8   // alignment of struct field with this type
    kind       uint8   // enumeration for C
    alg        *typeAlg  // algorithm table
    gcdata    *byte    // garbage collection data
    str       nameOff  // string form
    ptrToThis typeOff  // type for pointer to this type, may be zero
}

type iface struct {
    tab  *itab
    data unsafe.Pointer
}
// layout of Itab known to compilers
// allocated in non-garbage-collected memory
// Needs to be in sync with
// ../cmd/compile/internal/gc/reflect.go:/^func.dumptypestructs.
type itab struct {
    inter  *interfacetype
    _type  *_type
    link   *itab
    bad    int32
    inhash int32      // has this itab been added to hash?
    fun    [1]uintptr // variable sized
}

struct Iface
{
    Itab* tab;
    void* data;
};
struct Itab
{
    InterfaceType* inter;
    Type* type;
    void (*fun[])(void);
};

var w io.Writer

package main
import ("fmt")
func main(){
       var a interface{} = nil // tab = nil, data = nil
       var b interface{} = (*int)(nil) // tab 包含 *int 類型信息, data = nil
       fmt.Println(a==nil)
       fmt.Println(b==nil)
}

func IsNil(i interface{}) bool {
    defer func() {
        recover()
    }()
    vi := reflect.ValueOf(i)
    return vi.IsNil()
}

func (v Value) IsNil() bool 

func IsNil(i interface{}) bool {
    vi := reflect.ValueOf(i)
    if vi.Kind() == reflect.Ptr {
        return vi.IsNil()
    }
    return false
}

reflect.TypeOf()