// struct func sendMoney(from user1: inout User, to user2: inout User) { // これ自体は OK user1.money -= 100 user2.money += 100 } sendMoney(from: &user1, to: &user2) // OK sendMoney(from: &user1, to: &user1) // コンパイルエラー// struct func sendMoney(from user1: inout User, to user2: inout User) { // これ自体は OK user1.money -= 100 user2.money += 100 } sendMoney(from: &user1, to: &user2) // OK sendMoney(from: &user1, to: &user1) // コンパイルエラー