[swift-dev] Where are @_attributes documented?

[Joe Groff]

> On Dec 30, 2015, at 7:42 PM, Ling Wang <an00na at gmail.com> wrote:
> 
> Yes I’m submitting patches to stdlib. Thanks for pointing me to the doc folder.

Even if you're working on the stdlib, I wouldn't worry too much about using any internal attributes right away. The performance team usually handles adding those where needed.

-Joe

>> On Dec 30, 2015, at 7:35 PM, Joe Groff <jgroff at apple.com> wrote:
>> 
>> 
>>> On Dec 30, 2015, at 4:58 PM, Ling Wang via swift-dev <swift-dev at swift.org> wrote:
>>> 
>>> I want to submit some patches but I’m not sure whether I should apply some @_attributes(like @_transparent and @_semantics) that I see in stdlib to my API because I don’t know their meanings.
>> 
>> If it starts with an underscore, the answer is always "no, unless you're the standard library". These attributes are compiler-internal and not intended to be used by user code. We reserve the right to change them with reckless abandon.
>> 
>>> Where are they documented?
>> 
>> Some are documented in the compiler's 'doc/' subdirectory in various places.
>> 
>> -Joe
>