[swift-users] [swift-evolution] Padding structs

[Joe Groff]

> On Jan 19, 2016, at 11:00 AM, Alexandre Lopoukhine <superlopuh at gmail.com> wrote:
> 
> Thanks Joe,
> 
> I was wondering which group I should write to, but I decided that part of the question was related to the evolution of swift.
> 
> The part related to current usage stems from trying to encode a struct containing a UInt8 and UInt32, and it taking up 8 bytes, unexpectedly to me.
> 
> The same happens with a tuple containing the same values.

A C struct would be the same size by default, since UInt32's natural alignment is to 4 bytes. Aligned accesses are generally much more efficient (though less so on recent Intel and ARM microarchitectures, I hear).

-Joe