error break-value

error Стандарт: [§5.6]

break со значением допустим только в loop.

What it means#

break value is allowed only in loop, which is an expression; for and while always produce () (§5.6).

oxl✓ проверяется в CI

fn main() {
  for x in [1, 2, 3] {
    break x      // <- break-value
  }
}

error

break-value

oxl✓ проверяется в CI

fn firstOf(xs: List<i32>) -> i32 {
  var found = 0
  for x in xs {
    found = x
    break
  }
  found
}

Use loop { ... break result }, or store the value in a variable and break without a value.