Re: Remove deprecation warnings when compiling PG ~13 with OpenSSL 3.0~

Hi,

On 2023-06-21 11:53:44 +0900, Michael Paquier wrote:
> Compiling Postgres up to 13 with OpenSSL 3.0 leads to a couple of
> compilation warnings with what OpenSSL considers as deprecated, like:
> sha2_openssl.c: In function pg_sha384_init
> sha2_openssl.c:70:9: warning: SHA384_Init is deprecated =
> Since OpenSSL 3.0 [-Wdeprecated-declarations]
>    70 |         SHA384_Init((SHA512_CTX *) ctx);
>       |         ^~~~~~~~~~~
> /usr/include/openssl/sha.h:119:27: note: declared here
>   119 | OSSL_DEPRECATEDIN_3_0 int SHA384_Init(SHA512_CTX *c);
> 
> I was looking at the code of OpenSSL to see if there would be a way to
> silenced these, and found about OPENSSL_SUPPRESS_DEPRECATED.
> 
> I have been annoyed by these in the past when doing backpatches, as
> this creates some noise, and the only place where this counts is
> sha2_openssl.c.  Thoughts about doing something like the attached for
> ~13?

Wouldn't the proper fix be to backpatch 4d3db13621b? Just suppressing all
deprecations doesn't strike me as particularly wise, especially because we've
chosen a different path for 14+?

Greetings,

Andres Freund