Re: GinPageIs* don't actually return a boolean

On 2016-02-12 09:39:20 -0500, Tom Lane wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> > On Fri, Feb 12, 2016 at 8:48 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> >> E.g. if you include stdbool.h [ ginStepRight breaks ]
>
> > Ah-ha. OK, now I get it. So then I agree we should back-patch this
> > at least as far as 9.3 where MSVC 2013 became a supported platform,
>
> Um, no, that does not follow.

Well, these headers are generally buggy, so ...

> The unanswered question here is why,
> when we *have not* included stdbool.h and *have* typedef'd bool as
> just plain "char", we would get C99 bool behavior. There is something
> happening there that should not be happening, and I'm not really satisfied
> with the explanation "Microsoft is brain-dead as usual". I think we
> should dig deeper, because whatever is going on there may have deeper
> effects than we now realize.

Well,
http://archives.postgresql.org/message-id/d2106c2d-0f46-4cf9-af27-54f81ef6e20c%40postgrespro.ru
outlines how stdbool.h gets included. That happens fairly at the
begining of c.h. Later our definitions are guarded by ifdefs:

#ifndef bool
typedef char bool;
#endif

#ifndef true
#define true ((bool) 1)
#endif

#ifndef false
#define false ((bool) 0)
#endif

So we can lament that MS standard libraries include stdbool.h instead of
using _Bool. But I doubt that's going to buy us super much.

Btw, there's a distinct advantage including stdbool: Compilers actually
generate a fair bit better error messages/warnings in some cases. And
the generated code sometimes is a bit better, too.

Andres