Question

ARC forbids Objective-C objects in structs or unions despite marking the file -fno-objc-arc?
Why is this so?

I had the assumption that if you mark it -fno-objc-arc you don’t have this restriction.

Answer 1

If you got this message try __unsafe_unretained. It is only safe, if the objects in the struct are unretained.
Example: If you use OpenFeint with ARC the Class OFBragDelegateStrings says this error in a struct.

typedef struct OFBragDelegateStrings
{
     NSString* prepopulatedText;
     NSString* originalMessage;
} OFBragDelegateStrings;

to

typedef struct OFBragDelegateStrings
{
     __unsafe_unretained NSString* prepopulatedText;
     __unsafe_unretained NSString* originalMessage;
} OFBragDelegateStrings;