Does a break statement break from a switch/select?

Question

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.

A hopefully illustrative example:

loop:
for {
        switch expr {
        case foo:
                if condA {
                        doA()
                        break // like 'goto A'
                }

                if condB {
                        doB()
                        break loop // like 'goto B'                        
                }

                doC()
        case bar:
                // ...
        }
A:
        doX()
        // ...
}

B:
doY()
// ....

Yes, break breaks the inner switch.

https://play.golang.org/p/SZdDuVjic4

package main

import "fmt"

func main() {

myloop:
    for x := 0; x < 7; x++ {
        fmt.Printf("%d", x)
        switch {
        case x == 1:
            fmt.Println("start")
        case x == 5:
            fmt.Println("stop")
            break myloop
        case x > 2:
            fmt.Println("crunching..")
            break
        default:
            fmt.Println("idling..")
        }
    }
}

0idling..
1start
2idling..
3crunching..
4crunching..
5stop

Program exited.

Just from a switch block. There's plenty of examples in Golang own code you can examine (compare inner break with outer break).

This question might be too old already but I still think label makes our code become harder to read. Instead of breaking the for inside select, just set a flag for the loop and handle it inside select-case before invoking break. For example:

loop := true
for loop {
    select {
    case <-msg:
        // do your task here
    case <-ctx.Done():
        loop = false
        break
    }
}