Crystal: `next` accepts named arguments

[straight-shoota]

Arguments to next are parsed like arguments to method calls, but they shouldn't support named parameters:

next 1, foo: 2

This should probably raise a syntax error. Could also capture the named arguments and provide them somehow to the yielding scope, but that's probably too complicated - and not really useful.

If only named arguments are provided next foo: 2, it raises Index out of bounds.

[r00ster91]

That's also happening at break.

[MakeNowJust]

return statement accepts named arguments (of course not work). Because they are parsed by same parse_control_expression method.

Additionally yield accepts named arguments also, but we cannot refer these values. It should be fixed.

[straight-shoota]

If no positional arguments are present, named arguments could perhaps be transformed to a named tuple. So next foo: bar would be equal to next {foo: bar}. But it's not a huge difference, so probably not worth it to have this special case.

[asterite]

All of this works in Ruby, I would do nothing regarding this for now.

[MakeNowJust]

foo = while true
        break 1, foo: 1
      end
p foo

In Ruby it yields [1, {foo: 1}], but in Crystal it yields what?

[MakeNowJust]

Wow! Crystal ignore break and next value inside while loop... #1277