swift

f70676a3 - [Swiftify] Emit @availability when expansions contain Span (#81320)

[Swiftify] Emit @availability when expansions contain Span (#81320) This prevents errors when compiling for older targets using a newer compiler. rdar://150740330 (cherry picked from commit 59d7d3160ff42ce0bd3ec3cb7523aec1e7267b37)