Can this be closed now?

There are a few more edge cases not covered by the fix. Also a similar problem exists for yield and return being allowed outside of functions.

The current fix probably cannot handle breaks in nested loops, because having only a boolean indicator in_loop is not enough to keep track of the nesting. For example,

def f():
    a = 3
    while a:
        for i in range(10):
            print(a, i)
            if i == 2:
                break
        a -= 1
        if a == 1:
            break

The self.in_loop will be reset to false at the end of the for loop, but we will still be inside the while loop.

One solution might be to use an integer to keep track of the level of nesting.

Yeah, this is the edge case I was alluding to above.

The in_loop flag should actually be enough, if instead of setting to false, it just saves and then restores the prior value.

@OddCoincidence please take a look at the PR #542 for the fix. Thank you~