[Bug c/90081] stdint constant macros evaluating to wrong type

[harald at gigawatt dot nl]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90081

Harald van Dijk <harald at gigawatt dot nl> changed:

           What    |Removed                     |Added
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                 CC|                            |harald at gigawatt dot nl

--- Comment #4 from Harald van Dijk <harald at gigawatt dot nl> ---
(In reply to Martin Sebor from comment #3)
> UINT8_C(-5) isn't valid but expanding the macros to their arguments isn't
> conforming either.  C11 DR #456 suggests compiler magic is necessary to make
> the macros correct:
> http://www.open-std.org/jtc1/sc22/wg14/www/docs/summary.htm#dr_456 (Also see
> C99 DR 209: http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_209.htm).

It doesn't seem like compiler magic is really needed:

#define UINT8_C(x) ((__uint8_t) +(x##U))

This works correctly even in #if expressions because of the replacement of
__uint8_t by 0.