clang crashes in

--------------------
class allocator {
};
class basic_string     {
struct _Alloc_hider : allocator       {
char* _M_p;
};
_Alloc_hider _M_dataplus;
};
@implementation
CrashReporterUI -(void)awakeFromNib {
}
-(void)showCrashUI:(const basic_string&)dumpfile   {
}
@end
----------------------

$ clang -cc1 -emit-llvm-only crashreporter_osx.mii

Assertion failed: (CurOffs <= CurLayObj->first), function getObjCEncodingForStructureImpl