Re: Small memory fixes for pg_createsubcriber

=?utf-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilmari(at)ilmari(dot)org> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
>> libpq-fe.h has to be compilable by application code that has never
>> heard of pg_config.h let alone c.h, so we'd have to tread carefully
>> about not breaking that property. But it seems like this would be
>> worth looking into.

> The fallback code isn't exactly complicated, so we could just duplicate
> it in libpq-fe.h:

> #ifndef __has_attribute
> #define __has_attribute(attribute) 0
> #endif

The problem with that approach is the likelihood of stomping on
symbols that a calling application will use later. I think we
really need a controlling #ifdef check on some PG_FOO symbol
that we can be sure no outside application will have defined.
Roughly speaking,

#ifdef PG_USE_ALLOCATOR_CHECKS
#define pg_attribute_malloc __attribute__((malloc))
...
#else
#define pg_attribute_malloc
...
#endif

and then we could make definition of PG_USE_ALLOCATOR_CHECKS
be conditional on having the right compiler behavior, rather
than trusting that a nest of #ifdef checks is sufficient to
detect that.

regards, tom lane