> My understanding is that __builtin_choose_expr does ignore the > expression that is not chosen, so you must mean something other than I > what mean. Please post an example. The code void f_int(int *x); void f_float(float *x); #define is_int_ptr(x) __builtin_types_compatible_p((x),int *) #define f(x) __builtin_choose_expr(is_int_ptr(x), f_int(x), f_float(x)) will warn about incompatible pointer types when called with a pointer to an int and with a pointer to a float, although the chosen expression is valid in either case. Moreover, it will warn about "dereferencing type-punned pointer" when compiling with -O2. Joerg
