Re: retire MemoryContextResetAndDeleteChildren backwards compatibility macro

Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> writes:

> On 2023-Nov-13, Nathan Bossart wrote:
>
>> Shall we retire this backwards compatibility macro at this point? A search
>> of https://codesearch.debian.net/ does reveal a few external uses, so we
>> could alternatively leave it around and just update Postgres to stop using
>> it, but I don't think it would be too burdensome for extension authors to
>> fix if we removed it completely.
>
> Let's leave the macro around and just remove its uses in PGDG-owned
> code. Having the macro around hurts nothing, and we can remove it in 15
> years or so.

Is there a preprocessor symbol that is defined when building Postgres
itself (and extensions in /contrib/), but not third-party extensions (or
vice versa)? If so, the macro could be guarded by that, so that uses
don't accientally sneak back in.

There's also __attribute__((deprecated)) (and and __declspec(deprecated)
for MSVC), but that can AFAIK only be attached to functions and
variables, not macros, so it would have to be changed to a static inline
function.

- ilmari