http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56870
Bug #: 56870 Summary: @catch handler broken with SEH Classification: Unclassified Product: gcc Version: 4.8.1 Status: UNCONFIRMED Severity: blocker Priority: P3 Component: objc AssignedTo: unassig...@gcc.gnu.org ReportedBy: js-...@webkeks.org When trying to use ObjC exceptions with the new SEH support, the caught object is not the ObjC object, but the _Unwind_Exception instead. Example: @try { id e = [Object new]; printf("@throw %p\n", e); @throw e; } @catch (id e) { printf("@catch %p\n", e); @throw e; } Expected behaviour: Both are the same pointer. Observed behaviour: They differ. Looking further into it, the second pointer is the pointer to the _Unwind_Exception (I added debug code in objc_exception_throw that outputs the pointer after the malloc. It is always the same that's received in the catch). So it seems the generated landing pad for ObjC code is wrong when using SEH. I think it is correct that the landing pad receives the _Unwind_Exception and not the ObjC object. But the landing pad needs to get the ObjC exception out of the _Unwind_Exception and give that back to the user instead of the _Unwind_Exception, which the user should never see. This seems to happen not only with 4.8, but also with 4.9. I marked this bug as blocker, as 4.8 made SEH the default, effectively breaking ObjC execptions on Windows.