Warn about overriding initializers without side effects
Wpacked-bitfield-compat
-C ObjC C++ ObjC++ Var(warn_packed_bitfield_compat) Init(1) Warning
+C ObjC C++ ObjC++ Var(warn_packed_bitfield_compat) Init(-1) Warning
Warn about packed bit-fields whose offset changed in GCC 4.4
Wparentheses