Re: pgsql: Improve performance of repeated CALLs within plpgsql procedures.

I wrote:
> Michael Paquier <michael@paquier.xyz> writes:
>> On Tue, Jan 26, 2021 at 03:28:39AM +0000, Tom Lane wrote:
>>> Improve performance of repeated CALLs within plpgsql procedures.

>> lapwing is generating a warning here:

> Yeah, I saw that last night.  It's weird, because that patch surely
> did not change anything that should affect defined-ness of retval.
> I plan to fix it by just immediately initializing retval, but I want
> to wait a little bit, because I'm curious to see if any other compilers
> complain.

Did that now.  A survey of the buildfarm finds all of these animals
warning about retval, in addition to lapwing:

 curculio      | 2021-01-26 11:30:20 | pl_handler.c:228: warning: 'retval' may be used uninitialized in this function
 damselfly     | 2021-01-26 11:30:28 | pl_handler.c:303:2: warning: 'retval' may be used uninitialized in this function
[-Wmaybe-uninitialized]
 locust        | 2021-01-26 11:14:42 | pl_handler.c:228: warning: 'retval' may be used uninitialized in this function
 mantid        | 2021-01-26 11:07:08 | pl_handler.c:303:2: warning: 'retval' may be used uninitialized in this function
[-Wmaybe-uninitialized]
 prairiedog    | 2021-01-25 13:19:02 | pl_handler.c:227: warning: 'retval' may be used uninitialized in this function
 prion         | 2021-01-26 10:03:14 |
/home/ec2-user/bf/root/HEAD/pgsql.build/../pgsql/src/pl/plpgsql/src/pl_handler.c:303:2:warning: 'retval' may be used
uninitializedin this function [-Wmaybe-uninitialized] 
 rhinoceros    | 2021-01-26 09:52:17 | pl_handler.c:303:2: warning: 'retval' may be used uninitialized in this function
[-Wmaybe-uninitialized]
 sidewinder    | 2021-01-26 11:45:19 | pl_handler.c:303:2: warning: 'retval' may be used uninitialized in this function
[-Wmaybe-uninitialized]
 skate         | 2021-01-26 09:06:47 | pl_handler.c:303:2: warning: 'retval' may be used uninitialized in this function
[-Wmaybe-uninitialized]
 takin         | 2021-01-26 08:51:19 | pl_handler.c:303:2: warning: 'retval' may be used uninitialized in this function
[-Wmaybe-uninitialized]

Some of these may predate this commit (the one from prairiedog
clearly does).  I also noted a few animals complaining about -Wclobber:

 francolin     | 2021-01-14 02:20:10 |
/home/andres/build/buildfarm-francolin/HEAD/pgsql.build/../pgsql/src/pl/plpgsql/src/pl_handler.c:227:9:warning:
variable'retval' might be clobbered by 'longjmp' or 'vfork' [-Wclobbered] 
 piculet       | 2021-01-14 04:16:30 |
/home/andres/build/buildfarm-piculet/HEAD/pgsql.build/../pgsql/src/pl/plpgsql/src/pl_handler.c:227:9:warning: variable
'retval'might be clobbered by 'longjmp' or 'vfork' [-Wclobbered] 
 rorqual       | 2021-01-14 02:20:10 |
/home/andres/build/buildfarm-atomics-spinlocks/HEAD/pgsql.build/../pgsql/src/pl/plpgsql/src/pl_handler.c:227:9:warning:
variable'retval' might be clobbered by 'longjmp' or 'vfork' [-Wclobbered] 
 serinus       | 2021-01-26 09:44:08 |
/home/bf/build/buildfarm-serinus/HEAD/pgsql.build/../pgsql/src/pl/plpgsql/src/pl_handler.c:227:16:warning: variable
'procedure_resowner'might be clobbered by 'longjmp' or 'vfork' [-Wclobbered] 
 serinus       | 2021-01-26 09:44:08 |
/home/bf/build/buildfarm-serinus/HEAD/pgsql.build/../pgsql/src/pl/plpgsql/src/pl_handler.c:228:9:warning: variable
'retval'might be clobbered by 'longjmp' or 'vfork' [-Wclobbered] 
 skink         | 2021-01-13 19:41:43 |
/home/andres/build/buildfarm/HEAD/pgsql.build/../pgsql/src/pl/plpgsql/src/pl_handler.c:227:9:warning: variable 'retval'
mightbe clobbered by 'longjmp' or 'vfork' [-Wclobbered] 

and made an effort to silence that too.

            regards, tom lane