Re: uint64_t fails with C++

[Peter O'Gorman]

On 12/07/2011 12:08 PM, Werner LEMBERG wrote:
> > >     #if defined UINT64_MAX || defined uint64_t
> > >     typedef uint64_t TA_ULongLong;
> > >     #else
> > >     #  error "No unsigned 64bit wide data type found."
> > >     #endif
> >
> > stdint.h will not define UINT64_MAX if __cplusplus is defined unless
> > __STDC_LIMIT_MACROS is defined before you include it.
>
> Thanks.  However, this still doesn't explain why autoconf (using g++!)
> says that uint64_t exists: __STDC_LIMIT_MACROS is not used in any part
> of autoconf.
>
> Am I missing something?
>
>
>      Werner
>
>
> PS: If using __STDC_LIMIT_MACROS is the `official' way to handle
>      uint64 I suggest to update the autoconf documentation accordingly.

It's nothing to do with autoconf really, configure correctly finds 
uint64_t, your C program then checks for UINT64_MAX or a uint64_t macro 
instead of #include <config.h> and checking for HAVE_UINT64_T.

C++ compilers do not get these definition from stdint.h unless 
__STDC_LIMIT_MACROS is defined, the macros are in C99 and later, but 
were not in the C++ standard of the day (I don't know if they're in 
later C++ standards), so aren't defined for C++ compilers by default.

Peter