Potential us of initialized memory in xlogrecovery.c

Hello,

Today, I compiled the master branch of Postgres with the following GCC
version:

gcc (GCC) 13.1.1 20230511 (Red Hat 13.1.1-2)

I got the following warning:

[701/2058] Compiling C object src/backend/postgres_lib.a.p/access_transam_xlogrecovery.c.o
In function ‘recoveryStopsAfter’,
    inlined from ‘PerformWalRecovery’ at ../src/backend/access/transam/xlogrecovery.c:1749:8:
../src/backend/access/transam/xlogrecovery.c:2756:42: warning: ‘recordXtime’ may be used uninitialized
[-Wmaybe-uninitialized]
 2756 |                         recoveryStopTime = recordXtime;
      |                         ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
../src/backend/access/transam/xlogrecovery.c: In function ‘PerformWalRecovery’:
../src/backend/access/transam/xlogrecovery.c:2647:21: note: ‘recordXtime’ was declared here
 2647 |         TimestampTz recordXtime;
      |                     ^~~~~~~~~~~

Investigating this issue I see a potential assignment in
xlogrecovery.c:2715. Best I can tell the warning looks real. Similar
functions in this file seem to initialize recordXtime to 0. Attached is
a patch which does just that.

--
Tristan Partin
Neon (https://neon.tech)