[swift-evolution] [Pre-proposal] Fix function type grammar

[Chris Lattner]

> On Jul 3, 2016, at 9:04 AM, Anton Zhilin via swift-evolution <swift-evolution at swift.org> wrote:
> 
> Chris Lattner via swift-evolution <swift-evolution at ...> writes:
> 
>> Hi Anton,
>> 
>> This looks correct, but what is the proposal “for”?  This seems like it 
> is just encoding what SE-0066 was about.
>> 
>> -Chris
> 
> Questions about that proposal are often risen on the list.
> Some think that we will still be able to supply () argument
> to () -> T functions.
> 
> To clear that up completely, I suggest adding this grammar change
> to SE-0066 or one of the newer proposals. Key idea is that parentheses
> are part of function type grammar and have nothing common with tuples
> or unit type.

Sure, that makes sense to me.  Please submit a PR that expands on SE-0066 when this settles, I don’t think we need another review cycle.  Thank you!

-Chris