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

[Anton Zhilin]

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.