Loop Variable Change

Go 1.22 changed the scoping rules for for and range loop variables. Before 1.22, the loop variable was a single variable reused across every iteration, which broke code that spawned goroutines or registered callbacks inside the loop. Since 1.22, each iteration gets its own copy, and a whole class of subtle bugs disappears. This lesson explains the old behavior, the classic bug that motivated the change, the new semantics, and how to migrate safely.