[APINotes] Don't apply API notes to non-definitions of structs. (#69)
There are two reasons for this:
- It doesn't really seem appropriate for forward-declared structs to
pick up attributes.
- In a proper definition `struct X { ... }`, the first `struct X`
counts as a declaration, which means the API note attributes can get
added ahead of time. Later on, when we try to add them /again/,
they'll replace the attribute added at the first point rather than
whatever the user wrote in source after the close brace. This also
applies if there are any forward declarations before the definition.
There is a downside: API notes now can't affect tag types that are
/never/ defined (for example, structs that are forward-declared for
use in pointers). Any annotations one might want to apply to such
a type must be written in source.
rdar://problem/29981732
(cherry picked from commit 911df2f93842d956d2848d8c10366b742cc4eef2)
5 files changed
