Re: Small memory fixes for pg_createsubcriber

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> =?utf-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilmari(at)ilmari(dot)org> writes:
>> Andres Freund <andres(at)anarazel(dot)de> writes:
>>> Particularly for something like libpq it's not quitetrivial to add
>>> attributes like this, of course. We can't even depend on pg_config.h.
>>> One way would be to define them in libpq-fe.h, guarded by an #ifdef, that's
>>> "armed" by a commandline -D flag, if the compiler is supported?
>
>> Does it need a -D flag, wouldn't __has_attribute(malloc) (with the
>> fallback definition in c.h) be enough?
>
> 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

And then do something like this:

#if __has_attribute (malloc)
#define pg_attribute_malloc __attribute__((malloc))
#define pg_attribute_deallocator(...) __attribute__((malloc(__VA_ARGS__)))
#else
#define pg_attribute_malloc
#define pg_attribute_deallocator(...)
#endif

> regards, tom lane

- ilmari