Обсуждение: Dubious coding in nbtinsert.c

Buildfarm member curculio, which doesn't usually produce
uninitialized-variable warnings, is showing one here:

nbtinsert.c: In function '_bt_doinsert':
nbtinsert.c:411: warning: 'curitemid' may be used uninitialized in this function
nbtinsert.c:411: note: 'curitemid' was declared here

I can see its point: curitemid is set only if !inposting.
While the first two uses of the value are clearly reached
only if !inposting, it's FAR from clear that it's impossible
to reach "ItemIdMarkDead(curitemid);" without a valid value.
Could you clean that up?

            regards, tom lane

On Thu, Apr 8, 2021 at 12:19 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Buildfarm member curculio, which doesn't usually produce
> uninitialized-variable warnings, is showing one here:
>
> nbtinsert.c: In function '_bt_doinsert':
> nbtinsert.c:411: warning: 'curitemid' may be used uninitialized in this function
> nbtinsert.c:411: note: 'curitemid' was declared here
>
> I can see its point: curitemid is set only if !inposting.
> While the first two uses of the value are clearly reached
> only if !inposting, it's FAR from clear that it's impossible
> to reach "ItemIdMarkDead(curitemid);" without a valid value.
> Could you clean that up?

I'll take care of it shortly.

You had a near-identical complaint about a compiler warning that led
to my commit d64f1cdf2f4 -- that one involved _bt_check_unique()'s
curitup, while this one is about curitemid. While I have no problem
silencing this compiler warning now, I don't see any reason to not
just do the same thing again. Which is to initialize the pointer to
NULL.

-- 
Peter Geoghegan

Peter Geoghegan <pg@bowt.ie> writes:
> You had a near-identical complaint about a compiler warning that led
> to my commit d64f1cdf2f4 -- that one involved _bt_check_unique()'s
> curitup, while this one is about curitemid. While I have no problem
> silencing this compiler warning now, I don't see any reason to not
> just do the same thing again. Which is to initialize the pointer to
> NULL.

Works for me; if there is any bug in the logic, we'll get a core dump
and can investigate.

            regards, tom lane