[Bug c/82528] Warning for conversion from bool to enum

egallager at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Fri Oct 12 02:28:00 GMT 2018


Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
             Status|NEW                         |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #3 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Martin Sebor from comment #2)
> Yes, I also thought of bug 82272.  The challenge with having the macros true
> and false expand to some built-ins (like __true and __false) is that it
> would be at odds with the C requirements that they be suitable for use in
> #if preprocessing directives and expand to the integer constants 1 and 0. 
> At a minimum, the preprocessor would need to be made aware of these
> built-ins.  The more esoteric  problems stemming from having them expand to
> non-literals is in preprocessor tricks like:
>   #include <stdbool.h>
>   #define CAT(a, b)  a ## b
>   #define CONCAT(a, b) CAT (a, b)
>   int i = CONCAT(1, true);
> It's not clear that the standard actually requires the above to expand to
> '11' (as opposed to causing an error if true were defined to (1), i.e., 1 in
> parentheses) so maybe this is a non-issue.  As H. Peter Anvin suggests in
> the related bug, it might be helpful to get this clarified and perhaps even
> tightened up for C2X.

The discussion seems to be more in 82272 so I guess that's the one this is a
dup of.

*** This bug has been marked as a duplicate of bug 82272 ***

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