swift234

Support short-form @available attributes.

Allow availability attributes of the form:

  @available(iOS 8.0, OSX 10.10, *)
  func foo() { }

This form is intended for use by third-party developers when annotating their
own declarations and uses the same syntax as #available(). This annotation
says that on iOS foo() is available on version 8.0 and newer; on OSX it is
available on 10.10; and on any other un-mentioned platform it considered
available on the minimum deployment target and greater. Just like with

For now, we support this form during parsing by synthesizing multiple implicit
long-form @available attributes. So, for example, the above annotation will
synthesize two implicit attributes:

  @available(iOS, introduced=8.0)
  @available(OSX, introduced=10.10)
  func foo() { }

Synthesizing attributes in this way is not ideal -- it makes for a poor Fix-It
experience, among other things -- but it exposes the short-form syntax with
minimal invasiveness.

rdar://problem/20938565

Swift SVN r28647