Re: Small memory fixes for pg_createsubcriber

Andres Freund <andres(at)anarazel(dot)de> writes:

> Hi,
>
> On 2025-02-12 11:02:04 -0500, Tom Lane wrote:
>> I wish we had some way to detect misuses automatically ...
>>
>> This seems like the sort of bug that Coverity could detect if only it
>> knew to look, but I have no idea if it could be configured that way.
>> Maybe some weird lashup with a debugging malloc library would be
>> another way.
>
> Recent gcc actually has a fairly good way to detect this kind of issue:
> https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute
> in particular, the variant of the attribute with "deallocator".

[...]

> Note that that doesn't just require adding the attributes to
> PQescapeIdentifier() etc, but also to pg_malloc(), as the latter is how gcc
> knows that pg_pfree() is a deallocating function.
>
>
> 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?

- ilmari