Thread: silence GCC4 warning
This patch silences a GCC 4.0 warning about a potentially-uninitialized
variable in pl_comp.c, and makes some minor associated cleanups. Barring
any objections I'll apply this to HEAD tomorrow.
-Neil
Index: src/pl/plpgsql/src/pl_comp.c
===================================================================
RCS file: /var/lib/cvs/pgsql/src/pl/plpgsql/src/pl_comp.c,v
retrieving revision 1.91
diff -c -r1.91 pl_comp.c
*** src/pl/plpgsql/src/pl_comp.c 10 Jun 2005 16:23:11 -0000 1.91
--- src/pl/plpgsql/src/pl_comp.c 4 Jul 2005 07:48:09 -0000
***************
*** 1369,1375 ****
HeapTuple attrtup = NULL;
Form_pg_attribute attrStruct;
HeapTuple typetup = NULL;
! char *cp[2];
char *colname[1];
int qualified_att_len;
int numdots = 0;
--- 1369,1375 ----
HeapTuple attrtup = NULL;
Form_pg_attribute attrStruct;
HeapTuple typetup = NULL;
! char *cp[2] = {NULL, NULL};
char *colname[1];
int qualified_att_len;
int numdots = 0;
***************
*** 1389,1410 ****
{
if (word[i] == '.' && ++numdots == 2)
{
! cp[0] = (char *) palloc((i + 1) * sizeof(char));
! memset(cp[0], 0, (i + 1) * sizeof(char));
memcpy(cp[0], word, i * sizeof(char));
/*
* qualified_att_len - one based position + 1 (null
* terminator)
*/
! cp[1] = (char *) palloc((qualified_att_len - i) * sizeof(char));
! memset(cp[1], 0, (qualified_att_len - i) * sizeof(char));
memcpy(cp[1], &word[i + 1], (qualified_att_len - i - 1) * sizeof(char));
break;
}
}
relvar = makeRangeVarFromNameList(stringToQualifiedNameList(cp[0], "plpgsql_parse_tripwordtype"));
classOid = RangeVarGetRelid(relvar, true);
if (!OidIsValid(classOid))
--- 1389,1411 ----
{
if (word[i] == '.' && ++numdots == 2)
{
! cp[0] = (char *) palloc0((i + 1) * sizeof(char));
memcpy(cp[0], word, i * sizeof(char));
/*
* qualified_att_len - one based position + 1 (null
* terminator)
*/
! cp[1] = (char *) palloc0((qualified_att_len - i) * sizeof(char));
memcpy(cp[1], &word[i + 1], (qualified_att_len - i - 1) * sizeof(char));
break;
}
}
+ /* We must have found a match */
+ Assert(i < qualified_att_len);
+
relvar = makeRangeVarFromNameList(stringToQualifiedNameList(cp[0], "plpgsql_parse_tripwordtype"));
classOid = RangeVarGetRelid(relvar, true);
if (!OidIsValid(classOid))
Neil Conway <neilc@samurai.com> writes:
> This patch silences a GCC 4.0 warning about a potentially-uninitialized
> variable in pl_comp.c,
AFAICT, gcc4's default behavior is to warn about
int foo;
somefunc(&foo);
which unfortunately is a very common usage that I'm not real thrilled
about having to fix every occurrence of. I've been meaning to look into
whether they provided a pragma or something to mark function parameters
as output-only, so that this message could be suppressed where
appropriate without adding a lot of useless initializations.
In the meantime, I don't see the point of patching just one place.
regards, tom lane
Tom Lane wrote: > AFAICT, gcc4's default behavior is to warn about > > int foo; > > somefunc(&foo); A simple test shows that this is not the case, even with lots of -W options. -- Peter Eisentraut http://developer.postgresql.org/~petere/
Peter Eisentraut wrote: > A simple test shows that this is not the case, even with lots of -W > options. Right -- AFAICS we only get the following warnings of this class with GCC 4.0 on current sources: % gcc --version gcc-4.0 (GCC) 4.0.1 20050701 (prerelease) (Debian 4.0.0-12) [...] % make -s clean all [...] In file included from /home/neilc/pgsql/src/backend/regex/regexec.c:1070: /home/neilc/pgsql/src/backend/regex/rege_dfa.c: In function 'getvacant': /home/neilc/pgsql/src/backend/regex/rege_dfa.c:581: warning: 'lastap.ss' may be used uninitialized in this function /home/neilc/pgsql/src/backend/regex/rege_dfa.c:581: warning: 'lastap.co' may be used uninitialized in this function /home/neilc/pgsql/src/backend/utils/adt/inet_net_ntop.c: In function 'inet_net_ntop_ipv6': /home/neilc/pgsql/src/backend/utils/adt/inet_net_ntop.c:427: warning: 'cur.len' may be used uninitialized in this function /home/neilc/pgsql/src/backend/utils/adt/inet_net_ntop.c:427: warning: 'best.len' may be used uninitialized in this function /home/neilc/pgsql/src/interfaces/ecpg/pgtypeslib/datetime.c: In function 'PGTYPESdate_defmt_asc': /home/neilc/pgsql/src/interfaces/ecpg/pgtypeslib/datetime.c:335: warning: 'tm.tm_mday' may be used uninitialized in this function /home/neilc/pgsql/src/interfaces/ecpg/pgtypeslib/datetime.c:335: warning: 'tm.tm_mon' may be used uninitialized in this function /home/neilc/pgsql/src/interfaces/ecpg/pgtypeslib/datetime.c:335: warning: 'tm.tm_year' may be used uninitialized in this function /home/neilc/pgsql/src/pl/plpgsql/src/pl_comp.c: In function 'plpgsql_parse_tripwordtype': /home/neilc/pgsql/src/pl/plpgsql/src/pl_comp.c:1372: warning: 'cp[0]' may be used uninitialized in this function /home/neilc/pgsql/src/pl/plpgsql/src/pl_comp.c:1372: warning: 'cp[1]' may be used uninitialized in this function (Plus many errors regarding signedness, which is a separate matter.) All these warnings like somewhat reasonable, AFAICS: while the code may actually always initialize the variables before using them, it's understandable that the compiler can't infer this automatically. And this is surely a tiny fraction of the changes that would be required if something as fundamental as initialization via out parameters was broken. -Neil
Neil Conway <neilc@samurai.com> writes:
> Peter Eisentraut wrote:
>> A simple test shows that this is not the case, even with lots of -W
>> options.
> Right -- AFAICS we only get the following warnings of this class with
> GCC 4.0 on current sources:
Hmm ... my comments were based on experiments with a prerelease gcc4
that was circulating inside Red Hat; IIRC it showed some hundreds of
warnings of this type on the PG sources :-(. It sounds like they've
improved it somewhat, but I'm still not clear on what it is warning
about that prior releases did not.
regards, tom lane