[swift-evolution] [Proposal] Use inout at function call sites

[Joe Groff]

> On Jan 29, 2016, at 2:49 PM, Dmitri Gribenko via swift-evolution <swift-evolution at swift.org> wrote:
> 
> On Fri, Jan 29, 2016 at 2:44 PM, Trent Nadeau via swift-evolution
> <swift-evolution at swift.org> wrote:
>> The `&` prefix operator is a holdover from C where it is usually read as
>> "address of" and creates a pointer. While very useful in C due to its
>> pervasive use of pointers, its meaning is not the same
> 
> Since there is an implicit conversion from &x expression to
> UnsafePointer (for C interop), I have seen so many times people write
> buggy code with the & operator, assuming that it is returning a stable
> inner pointer to the data structure, like in C.  I don't have a
> preference for the replacement, but I strongly believe that & is the
> wrong way to spell this operation, because of the strong (and wrong!)
> connection with C syntax that people tend to make.  'inout' keyword at
> the call site sounds like a fine replacement to me.

Yeah, I like getting away from the baggage of the '&x' notation too. Implicit C pointer interop assumes that the C function has Swift-like by-value (for const) or inout-like (for non-const) semantics, and I like the idea of making that more explicit in the call site.

-Joe