Adds support for making pointers to C structs always import as OpaquePointer through API notes. This is needed to bring down the Android SDK to API level 23, since FILE is imported differently on API 23 vs 24.
Swift validates the retain/release operations for foreign reference types to check for obvious errors, e.g. a wrong parameter type or return type.
That logic was only running for C++ foreign reference types. This patch enables it for C foreign reference types as well.
rdar://158609723
The code for handling Swift conforms_to attributes was specific to
C++ record types. Generalize it to work on typedefs imported as
nominal types, also in C.
Fixes rdar://156290361.
Some of the patterns in the new test header are special-cased by
ClangImporter (for example, the names of typedefs become names of
imported structs).
Nested structs have been historically imported in Swift according to C
rules, that is, structs lexically declared nested in other structs are
imported into the global namespace anyway. For the same reason, C
structs have been mangled in Swift names as if they are declared in the
global namespace. These rules are problematic when importing C++, see
https://bugs.swift.org/browse/SR-12803.
Mads Odgaard
John Hui
Egor Zhdan
Doug Gregor
zoecarver
Dmitri Gribenko