for-loops and declaration-like init expressions

[John Lenz]

Would this still be legal, in this scheme?

  for ((function x(){}); ;) x  // 0
  for ((class x(){}); ;) x  // 0



On Thu, Jun 5, 2014 at 7:58 AM, Andreas Rossberg <rossberg at google.com>
wrote:

> C-style for-loops allow declarations as init statements, but only some
> of them. Yet, the others (function and class) are actually
> syntactically legal in that position as well, because they are simply
> parsed as expressions. Consider:
>
>   let x = 0
>   for (let x = 1; ;) x  // 1
>   for (const x = 1; ;) x  // 1
>   for (function x(){}; ;) x  // 0
>   for (class x(){}; ;) x  // 0
>


> I think these latter two examples violate the principle of least
> surprise. I wonder if it wouldn't be cleaner to rule them out, by
> imposing the same lookahead restrictions on for-loop init expressions
> as there are for expression statements.
>
> The one caveat is that for function, that would actually be a breaking
> change, but is it likely to be a real world one?
>
> What do you think?
>
> /Andreas
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