将结构B（从结构A继承）附加到结构A的切片上

I have a struct B which inherits from the struct A. I have another struct C (which contains a slice of structs A) and I want to append B to C.

package main

type A struct {
    target string
}

type B struct{
    A
    values []int
}

type C struct{
    Cols []*A
}

func main() {

var values = []int{1,2,3}
var col1 = C{} 
var col2 = &B {
    A: A{
        target: "txt",
    },
    values: values,
    }

col1.Cols = append(col1.Cols, col2)

}

When running this code, it generates an error: cannot use col2 (type *B) as type *A in append

What's wrong please ? I'm newer

Ps: sorry for my bad English

col1.Cols is type *A, col2 is type *B, col2.A is type A, if you want to add new element to the slices, they should be of the same type. so if you change the last statement to

col1.Cols = append(col1.Cols, &col2.A)

it will work.