[RFC v2 1/3] cdefs: Add __bool

[Zack Weinberg]

On Tue, Sep 2, 2025, at 3:26 PM, Alejandro Colomar wrote:
> Hi Joseph,
>> 4. As I noted in the previous discussion, we should actually document
>>    things in terms of *features* (on top of C90/C++98) required for
>>    using the installed headers, not compiler versions.
>
> Okay; can we require that a compiler supports _Bool?  Is that too much
> to ask from a compiler?

_Bool and <stdbool.h> were added in C1999.  I think it would be
reasonable for us to require a C1999-compliant compiler for use of the
installed headers.

I might even be persuaded to raise the lower bound all the way to C2011,
but I'd want to see solid evidence that the installed base of compilers
and compiler-adjacent objects that don't support C2011 additions (this
latter category includes all sorts of odd things that don't get updated
nearly as regularly as production C compilers, such as
<https://github.com/antlr/grammars-v4/blob/master/c/C.g4>) was
_vanishingly_ small first.

zw