should_fail.go

package main

import "fmt"

type readonly struct{}
type readwrite struct{}

type dbAcl interface{ readonly | readwrite }

type Driver[acl dbAcl] struct {
	value int
}

func (d *Driver[_]) Read() int {
	return d.value
}

func (d *Driver[readwrite]) Write(i int) {
	d.value = i
}

func NewReadOnly() Driver[readonly] {
	return Driver[readonly]{value: 15}
}

func NewReadWrite() Driver[readwrite] {
	return Driver[readwrite]{value: 15}
}

func main() {
	drw := NewReadWrite()
	fmt.Println(drw.Read())
	drw.Write(10)
	fmt.Println(drw.Read())

	dro := NewReadOnly()
	fmt.Println(dro.Read())
	dro.Write(10)
	fmt.Println(dro.Read())
}