The value is assigned means that generate a copy.

assignment_copy.go

package main

import "fmt"

type Pool struct {
	array [3]int
}

func main() {
	a := [...]int{1, 2, 3}
	pool := Pool{
		array: a,
	}
	fmt.Printf("Pool: %v\n", pool)
	a[0] = 4
	fmt.Printf("Pool: %v\n", pool)
	pool.array = a
	fmt.Printf("Pool: %v\n", pool)
	a[1] = 5
	fmt.Printf("Pool: %v\n", pool)
	b := a
	fmt.Printf("B: %v\n", b)
	a[2] = 6
	fmt.Printf("B: %v\n", b)
	b[2] = 7
	fmt.Printf("A: %v\n", a)

}

// Output:
// Pool: {[1 2 3]}
// Pool: {[1 2 3]}
// Pool: {[4 2 3]}
// Pool: {[4 2 3]}
// B: [4 5 3]
// B: [4 5 3]
// A: [4 5 6]