vitaut 🤍❤️🤍 🇺🇦Feb 22
So one side effect of C being a mess is that bool and char constants are formatted as integers by default. You have to either cast them to the correct type or use an explicit format specifier which is a bit annoying.
Show threadThiago AdamsFeb 22
@vitaut do you mean true/false constants?
They are _Bool type in C23
Char constants still int .
Show threadAndre WeissflogFeb 22
@thradams @vitaut _Bool goes all the way back to C99, C23 actually deprecated it in favour of 'bool' (eg. stdbool.h no longer needed), both are "proper" bools, but AFAIK the C standard doesn't enforce a specific size
Show threadAndre WeissflogFeb 22
@thradams @vitaut also I suspect that the problem might be that _Bool/bool implicitly converts to int (eg I guess in vararg lists, bools are passed as int, not sure though)
Show threadvitaut 🤍❤️🤍 🇺🇦Feb 22
@floooh @thradams I’m not using varargs, the problem is that true/false has int type in C11
Show threadvitaut 🤍❤️🤍 🇺🇦Feb 22
@floooh @thradams so it doesn’t work with _Generic
Show threadJoe Groff (1M Context)Feb 22
@vitaut @floooh @thradams for back compat, how about your own <fmtbool.h> that re-#defines true and false as (_Bool)1 and (_Bool)0
Show threadAndre WeissflogFeb 22

@joe @vitaut @thradams hmm, clang (and gcc) seem to get it right?

https://www.godbolt.org/z/1xd83zbeW

Compiler Explorer - C

void bla_bool(bool b) { printf("A boolean: %d\n", b); } void bla_int(int i) { printf("An int: %d\n", i); } #define bla(x) _Generic((x), \ bool: bla_bool, \ int: bla_int \ )(x) int main() { bla(true); bla(false); bla(123); return 0; }

Show threadAndre Weissflog
@joe @vitaut @thradams ooopsi, wait Clang gets it wrong! One sec...
Feb 22 at 2:52pmWeb
Show threadAndre WeissflogFeb 22

@joe @vitaut @thradams ah ok, apparently it has been fixed in C23, but C11 gets it wrong:

https://www.godbolt.org/z/1TW3Kndb7

Compiler Explorer - C

void bla_bool(bool b) { printf("A boolean: %d\n", b); } void bla_int(int i) { printf("An int: %d\n", i); } #define bla(x) _Generic((x), \ bool: bla_bool, \ int: bla_int \ )(x) int main() { bla(true); bla(false); bla(123); return 0; }

Show threadAlexander MonakovFeb 22

@floooh @joe @vitaut @thradams true/false are keywords in C only since C23 (macros before)

incidentally, sizeof(true) is 1 in C23, 4 before

Show threadMartin UeckerFeb 22
@floooh @joe @vitaut @thradams You need to pass -std=c23