Am 13.12.23 um 09:01 schrieb Jeff King:
> On Tue, Dec 12, 2023 at 11:30:03PM +0100, René Scharfe wrote:
>
>> I wonder if
>> it's time to use the C99 type _Bool in our code. It would allow
>> documenting that only two possible values exist in cases like the one
>> above. That would be even more useful for function returns, I assume.
> I don't even know that we'd need much of a weather-balloon patch. I
> think it would be valid to do:
>
> #ifndef bool
> #define bool int
>
> to handle pre-C99 compilers (if there even are any these days). Of
> course we probably need some conditional magic to try to "#include
> <stdbool.h>" for the actual C99. I guess we could assume C99 by default
> and then add NO_STDBOOL as an escape hatch if anybody complains.
The semantics are slightly different in edge cases, so that fallback
would not be fully watertight. E.g. consider:
bool b(bool cond) {return cond == true;}
bool b2(void) {return b(2);}
b() returns false if you give it false and true for anything else. b2()
returns true.
With int as the fallback this becomes:
int b(int cond) {return cond == 1;}
int b2(void) {return b(2);}
Now only 1 is recognized as true, b2() returns 0 (false).
A coding rule to not compare bools could mitigate that. Or a rule to
only use the values true and false in bool context and to only use
logical operators on them.
René
