[CS2] Array destructuring bug

[boris-petrov]

x = ([a..., b]) ->
  console.log a, b

x [1, 2, 3, 4]

This produces the incorrect:

var x,
  slice = [].slice;

x = function(arg) {
  var arg, i;
  a = 2 <= arg.length ? slice.call(arg, 0, i = arg.length - 1) : (i = 0, []), b = arg[i++];
  return console.log(a, b);
};

x([1, 2, 3, 4]);

As you can see, the variable a is not defined anywhere and this blows up.

Using CoffeeScript 2.0.0-beta4.

PS. Actually b is not defined either.

[vendethiel]

Fixed by #4640. Not yet released.

[boris-petrov]

@vendethiel - is this supposed to be fixed in beta5? I have a case where it doesn't work with it. Should I try to create a small reproduction or the fix for this is not merged in beta5?

[vendethiel]

Please try to create a repro

[helixbass]

@GeoffreyBooth this seems to have been introduced by #4478. Should be reopened

([a..., b]) -> illustrates the problem - a and b aren't declared in the compilation:

var slice = [].slice;

(function(arg) {
  var arg, i;
  a = 2 <= arg.length ? slice.call(arg, 0, i = arg.length - 1) : (i = 0, []), b = arg[i++];
});

[helixbass]

Should be fixed by #4683

[boris-petrov]

Thanks for the quick fixes. I'll wait for beta6 then, hopefully it comes out soon. :)