Обсуждение: 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