error[E0426]: use of undeclared label `'a`
  --> $DIR/label_break_value_invalid.rs:6:19
   |
LL |             break 'a $val;
   |                   ^^ undeclared label `'a`
...
LL |                 mac2!(2);
   |                 -------- in this macro invocation
   |
   = note: this error originates in the macro `mac2` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0426]: use of undeclared label `'a`
  --> $DIR/label_break_value_invalid.rs:28:19
   |
LL |     let x: u8 = mac3!('b: {
   |                       -- a label with a similar name is reachable
LL |         if true {
LL |             break 'a 3;
   |                   ^^
   |                   |
   |                   undeclared label `'a`
   |                   help: try using similarly named label: `'b`

error[E0426]: use of undeclared label `'a`
  --> $DIR/label_break_value_invalid.rs:33:29
   |
LL |     let x: u8 = mac3!(break 'a 4);
   |                             ^^ undeclared label `'a`

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0426`.