CC obj/release/tolua/tolua_map.o
../tolua/tolua_map.c: In function ‘tolua_dobuffer’:
../tolua/tolua_map.c:732:39: error: value computed is not used [-Werror=unused-value]

Since its computing a boolean value which is the logical 'or' of two expressions, but the result is never used.  I've not seen this pattern before in C code, where logical operation are used on statements out side of conditions.  I think the "if" version is much clearer, and does the same time.