Invalid completion record on BreakStatement with label

[sebmck]

invalid completion record: {"type":"break","target":null}

var i = 0;
var s = '';

function* f() {
  s += 'a';
  while(i++ < 3) {
    s += 'b';
    label1: {
      s += 'c';
      break label1;
      s += 'd';
    }
    s += 'e';
  }
  s += 'f';
}

var g = f();
g.next();
assert.equal(s, 'abcebcebcef');

[sebmck]

Looks like it's due to the leap manager trying to resolve it to a loop when any expression can be in a label statement.

[benjamn]

What's the expected behavior? Can a labeled break statement break from a labeled statement that isn't a loop?

[sebmck]

Looks like it just breaks the current block. So in the original example code s += 'd'; after break label1; never gets ran.

For some context the example is taken from the traceur test suite.

[benjamn]

Interesting!

[sebmck]

@benjamn Great! Unrelated question but have the generator error messages been standardised? I'm running 6to5 against the Traceur tests (which is how I found this bug) and the error messages don't match up which isn't that big of a deal but just thought I'd ask.

[benjamn]

Most if not all errors in the generator spec just say "if X then throw a TypeError" with no specified message. I've tried to keep compatibility with V8 just so the tests work in Node v0.11, but maybe I'm over-testing those error messages…

[lukasmlady]

Another invalid completion record: {"type":"break","target":null}:

  go(function*() {
    // Enter mini event loop.
    eventLoop:
    while(true) {
      let {channel, value} = yield alts([stickiness, killChan]);

      switch(channel) {
        // When the stickiness changes.
        case stickiness:
          $navItems
            .find(".js-siteNavItemIcon")
            .each((idx, el) => resetIcon($(el), state.isSticky));

          break;

        case killChan:
          break eventLoop;
      }
    }
  });

If I remove the .each((idx, el) => resetIcon($(el), state.isSticky)); line, it works - so the problem is the arrow function.

If I replace the let {channel, value} = yield alts([stickiness, killChan]); with var in the beginning, then it works as well (even with the arrow function).

[benjamn]

@lukasmlady would you mind minimizing that example as far as possible (if it isn't already minimal) and opening a new issue? I think this bug might have a distinct root cause.

[lukasmlady]

@benjamn yep, will do.

[lukasmlady]

@benjamn Created #169.