Instead of a new attribute `@completionHandlerAsync`, allow the use of
the existing `renamed` parameter of `@available` to specify the
asynchronous alternative of a synchronous function.
No errors will be output from invalid names as `@completionHandlerAsync`
had, but if a function is correctly matched then it will be used to
output warnings when using the synchronous function in an asynchronous
context (as before).
Resolves rdar://80612731
The async refactorings ignore whether a completion handler had
`@escaping` or not. In preparation of fixing this, fix up all functions
to have `@escaping` for their completion handler parameter.
Also some small miscellaneous fixes in order to reduce the number of
warnings output on test failures and also the addition of `REQUIRES:
concurrency` on all tests.
When adding an async alternative, add the @completionHandlerAsync
attribute to the sync function. Check for this attribute in addition to
the name check, ie. convert a call if the callee has either
@completionHandlerAsync or a name that is completion-handler-like name.
The addition of the attribute is currently gated behind the experimental
concurrency flag.
Resolves rdar://77486504
