Break statements, The Go Programming Language Specification.
A “break” statement terminates execution of the innermost “for”,
“switch” or “select” statement.BreakStmt = "break" [ Label ] .
If there is a label, it must be that of an enclosing “for”, “switch”
or “select” statement, and that is the one whose execution terminates
(§For statements, §Switch statements, §Select statements).L: for i < n { switch i { case 5: break L } }
Therefore, the break
statement in your example terminates the switch
statement, the “innermost” statement.