Enable checking for uses of potentially unavailable APIs. There is
a frontend option to disable it: -disable-availability-checking.
This commit updates the SDK overlays with @availability() annotations for the
declarations where the overlay refers to potentially unavailable APIs. It also changes
several tests that refer to potentially unavailable APIs to use either #available()
or @availability annotations.
Swift SVN r27272
In source files that are in script mode, global variable initialization
expressions are eagerly executed. For this reason, disallow @availability
attributes having 'introduced=' on script-mode globals.
I had to rejigger a fair number of potential unavailability tests because they
weren't written with this distinction in mind.
Swift SVN r27137
Most tests were using %swift or similar substitutions, which did not
include the target triple and SDK. The driver was defaulting to the
host OS. Thus, we could not run the tests when the standard library was
not built for OS X.
Swift SVN r24504
This commit adds SILGen for references to potentially unavailable global
variables. We emit .None if the global variable is not available and
.Some(rvalue) if the global variable is available. I will add SILGen
for references to other kinds of potentially unavailable declarations in a
later commit.
Swift SVN r22556
