Обсуждение: C++ and bool constants (was Re: [NOVICE] gcc 3.0.1)

Leandro Fanzone <leandro@hasar.com> writes:
> I have compiled PostgreSQL 7.1.2 with gcc 3.0.1, and have the following
> problem: if I include first libpq++.h before iostream, id est:
> #include <libpq++.h>
> #include <iostream>
> the compiler complains:

> This is because somewhere in PostgreSQL you have the following code:

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

Yeah.  c.h has

#ifndef __cplusplus
#ifndef bool
typedef char bool;
#endif     /* ndef bool */
#endif     /* not C++ */

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

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

It's been like that for quite some time, but it's always struck me as
bizarre: if we're willing to trust a C++ compiler to provide type
bool, why would we not trust it to provide the literals true and false
as well?  ISTM the code should read

#ifndef __cplusplus

#ifndef bool
typedef char bool;
#endif

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

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

#endif     /* not C++ */

Does anyone have an objection to this?
        regards, tom lane

I like the change.

> Leandro Fanzone <leandro@hasar.com> writes:
> > I have compiled PostgreSQL 7.1.2 with gcc 3.0.1, and have the following
> > problem: if I include first libpq++.h before iostream, id est:
> > #include <libpq++.h>
> > #include <iostream>
> > the compiler complains:
> 
> > This is because somewhere in PostgreSQL you have the following code:
> 
> > #ifndef true
> > #define true ((bool)1)
> > #endif
> 
> Yeah.  c.h has
> 
> #ifndef __cplusplus
> #ifndef bool
> typedef char bool;
> #endif     /* ndef bool */
> #endif     /* not C++ */
> 
> #ifndef true
> #define true    ((bool) 1)
> #endif
> 
> #ifndef false
> #define false    ((bool) 0)
> #endif
> 
> It's been like that for quite some time, but it's always struck me as
> bizarre: if we're willing to trust a C++ compiler to provide type
> bool, why would we not trust it to provide the literals true and false
> as well?  ISTM the code should read
> 
> #ifndef __cplusplus
> 
> #ifndef bool
> typedef char bool;
> #endif
> 
> #ifndef true
> #define true    ((bool) 1)
> #endif
> 
> #ifndef false
> #define false    ((bool) 0)
> #endif
> 
> #endif     /* not C++ */
> 
> Does anyone have an objection to this?
> 
>             regards, tom lane
> 
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Pennsylvania19026
 

Fine for me also.

Leandro.

Tom Lane wrote:

> Leandro Fanzone <leandro@hasar.com> writes:
> > I have compiled PostgreSQL 7.1.2 with gcc 3.0.1, and have the following
> > problem: if I include first libpq++.h before iostream, id est:
> > #include <libpq++.h>
> > #include <iostream>
> > the compiler complains:
>
> > This is because somewhere in PostgreSQL you have the following code:
>
> > #ifndef true
> > #define true ((bool)1)
> > #endif
>
> Yeah.  c.h has
>
> #ifndef __cplusplus
> #ifndef bool
> typedef char bool;
> #endif   /* ndef bool */
> #endif   /* not C++ */
>
> #ifndef true
> #define true    ((bool) 1)
> #endif
>
> #ifndef false
> #define false   ((bool) 0)
> #endif
>
> It's been like that for quite some time, but it's always struck me as
> bizarre: if we're willing to trust a C++ compiler to provide type
> bool, why would we not trust it to provide the literals true and false
> as well?  ISTM the code should read
>
> #ifndef __cplusplus
>
> #ifndef bool
> typedef char bool;
> #endif
>
> #ifndef true
> #define true    ((bool) 1)
> #endif
>
> #ifndef false
> #define false   ((bool) 0)
> #endif
>
> #endif   /* not C++ */
>
> Does anyone have an objection to this?
>
>                         regards, tom lane