[swift-users] Simultaneous access to global tuple members

[Martin R]

In that example the tuple is a (stored) property of a class, not a global variable. And why does it crash for a global variable, but not for a local variable in a function?

(Sorry if I am overlooking something obvious.)

Martin


> On 8. Aug 2017, at 17:50, Guillaume Lessard <glessard at tffenterprises.com> wrote:
> 
> 
>> On Aug 8, 2017, at 01:11, Martin R via swift-users <swift-users at swift.org> wrote:
>> 
>> SE-0176 Enforce Exclusive Access to Memory (https://github.com/apple/swift-evolution/blob/master/proposals/0176-enforce-exclusive-access-to-memory.md) states that "Accesses to different stored properties of a struct or different elements of a tuple are allowed to overlap."
>> 
>> [snip]
>> 
>> Is there anything special with simultaneous access to members of a global tuple, or is this a bug?
> 
> Not a bug. The very next sentence after the one you quoted: “However, note that modifying part of a value type still requires exclusive access to the entire value”. The first example in that section (https://github.com/apple/swift-evolution/blob/master/proposals/0176-enforce-exclusive-access-to-memory.md#value-types) is similar to your example; it trips the dynamic enforcement mechanism for the same reason. The second example shows a possible workaround.
> 
> Sincerely,
> Guillaume Lessard
>