Fix main thread requirements on protocols #509
Merged
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In #359 I implemented marking classes as
MainThreadOnly
, but a glaring omission there is that protocols were not yet marked in a similar way.This PR rectifies that by changing how the
mutability
traits work, allowing implementing them forProtocolObject<P>
as well, which means we can now add "requirements" to protocols, such astrait MyProtocol: IsMainThreadOnly
, ortrait MyProtocol: IsRetainable
.We're still missing
IsRetainable
bounds on pretty much everything inAppKit
(and others) before we can make protocol overriding safe, but now at least the capability of adding those attributes is there.