[swift-dev] swift_retainCount in CoreFoundation

[Joe Groff]

> On Dec 26, 2015, at 12:52 PM, Philippe Hausler <phausler at apple.com> wrote:
> 
> 
>> On Dec 26, 2015, at 12:31 PM, Joe Groff <jgroff at apple.com <mailto:jgroff at apple.com>> wrote:
>> 
>>> 
>>> On Dec 25, 2015, at 9:02 PM, Philippe Hausler <phausler at apple.com <mailto:phausler at apple.com>> wrote:
>>> 
>>> > On Dec 22, 2015, at 1:08 PM, Joe Groff via swift-dev <swift-dev at swift.org <https://lists.swift.org/mailman/listinfo/swift-dev>> wrote:
>>> > 
>>> > It looks like the corelibs implementation of CoreFoundation references swift_retainCount in order to implement CFGetRetainCount. Is getting the retain count necessary to CF functionality, or can these functions be removed?
>>> 
>>> For some reason I was not on this list;
>>> So in response to your query about CF’s usage of CFGetRetainCount - I think we can safely forbid that function in the swift version since there is no safe way to use it (even CFMachPort is a bit dodgy for it’s usage).
>>> 
>>> It might take some surgery but I can probably excise that fairly simply.
>> 
>> That'd be awesome. Thanks Philippe! For CFMachPort's usage, since it's checking for a retainCount of 1, maybe we could use swift_isUniquelyReferenced* instead, which we do need to reliably support for COW.
>> 
>> -Joe
> 
> Actually the method that was being used there is not even compiled on mac targets, I was able to safely excise the usage and disallow the function in the Swift version of CF. 
> 
> I pushed this:
> https://github.com/apple/swift-corelibs-foundation/commit/d430c06fe417e285c5b120ccbf1d1082807e3b5c <https://github.com/apple/swift-corelibs-foundation/commit/d430c06fe417e285c5b120ccbf1d1082807e3b5c>
> 
> Which should no longer swift_retainCount in swift-corelibs-foundation builds anymore.

Nice, thanks again Philippe!

-Joe
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