Georg-Johann Lay <avr@xxxxxxxx> writes:
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> Hi, I would like to do something like
>
> static inline void foo (unsigned long x)
> {
> if (__builtin_constant_p (x))
> {
> asm volatile ("... %0" :: "n" (x));
> }
> else
> {
> __builtin_error ("foo must be used with a compile time constant");
> }
> }
>
> Is there a way to generate an error/warning/info by making gcc
> call error/warning/info?
>
> So that in the above case an understandable error message is printed.
Not really, no. It would be a useful feature. In C++ you can use
template tricks to implement this.
> Is there an anologon to __builtin_constant_p that is true for compile
> time constants only (constraint "n" in the abobe case, but not all
> of "i")?
No.
Ian
