[PATCH] D87331: Sema: add support for `__attribute__((__swift_error__))`

[John McCall via Phabricator via cfe-commits]

rjmccall added inline comments.


================
Comment at: clang/include/clang/Basic/Attr.td:2128
+  ];
+  let Subjects = SubjectList<[Function, ObjCMethod], ErrorDiag>;
+  let Documentation = [SwiftErrorDocs];
----------------
compnerd wrote:
> aaron.ballman wrote:
> > Should this apply to function-like things such as blocks or function pointers? If so, you should use `HasFunctionProto`.
> I believe not.
Correct, it's just declared functions for now.


================
Comment at: clang/include/clang/Basic/AttrDocs.td:3394
+parameter. Currently, the error parameter is always the last parameter of type
+``NSError**`` or ``CFErrorRef*``.  Swift will remove the error parameter from
+the imported API. When calling the API, Swift will always pass a valid address
----------------
compnerd wrote:
> aaron.ballman wrote:
> > Canonical type or are typedefs to these types also fine? May want to mention that the type has to be cv-unqualified, but I do wonder whether something like `NSError * const *` is fine.
> I am definitely not the authority on this, but I believe that the common thing is to take `NSError **` or `CFErrorRef **` by canonical name.  The cv-qualified versions, except on the outermost pointer, is something that can be treated as valid, though it is certainly extremely unusual.  I've added test cases for them as well.
`NSError * const *` actually does not really work; the whole point is that this is an out-parameter.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D87331/new/

https://reviews.llvm.org/D87331