>>> From: Rick Mann <rm...@latencyzero.com> >>> Subject: ARC and reinterpret_cast? >>> Date: July 7, 2012 9:13:29 PM PDT >>> To: Cocoa-Dev List <cocoa-dev@lists.apple.com> >>> >>> Hi. I'd like to write code like this: >>> >>> MyObject* foo = reinterpret_cast<__bridge MyObject*> (someVoidPointer); >>> >>> But the compiler doesn't like it. It's perfectly happy with: >>> >>> MyObject* foo = (__bridge MyObject) someVoidPointer; >>> >>> this is in a .mm file. >>> >>> The error is: >>> >>> error: type name requires a specifier or qualifier >>> MyObject* me = reinterpret_cast<__bridge MyObject*> (inRefCon); >>> ^ >>> error: expected '>' >>> MyObject* me = reinterpret_cast<__bridge MyObject*> (inRefCon); >>> ^ >>>> >>> note: to match this '<' >>> MyObject* me = reinterpret_cast<__bridge MyObject*> (inRefCon); >>> ^ >>> Is it a bug in the compiler, or am I doing something wrong?
Well, it's definitely an ugly error message; that's worth a bug. The answer is that reinterpret_cast is redundant with __bridge. Bridging casts are essentially a different kind of named cast: they document intent more precisely than the general cast syntax, and they impose their own well-formedness rules about the operand and result type. So you're not getting any extra safety here. This is documented in the ARC specification: http://clang.llvm.org/docs/AutomaticReferenceCounting.html#objects.operands.casts 3.2.4. Bridged casts A bridged cast is a C-style cast annotated with . . . In theory there's nothing preventing us from allowing these keywords on named casts (although it would only be appropriate on reinterpret_cast), but our sense is that doing so would only confuse the issue more by suggesting subtle differences when none apply. John. _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
