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* Re: PG19beta1: GCC 16.1.1 warning: ‘actual_arg_types’ may be used uninitialized in clauses.c
@ 2026-06-04 15:07 Nathan Bossart <nathandbossart@gmail.com>
0 siblings, 2 replies; 5+ messages in thread
From: Nathan Bossart @ 2026-06-04 15:07 UTC (permalink / raw)
To: Hans Buschmann <buschmann@nidsa.net>; +Cc: pgsql-hackers
On Thu, Jun 04, 2026 at 02:42:18PM +0000, Hans Buschmann wrote:
> 839/2360] Compiling C object src/backend/postgres_lib.a.p/optimizer_util_clauses.c.o
> ../src/backend/optimizer/util/clauses.c: In function ‘recheck_cast_function_args.isra’:
> ../src/backend/optimizer/util/clauses.c:5152:19: warning: ‘actual_arg_types’ may be used uninitialized [-Wmaybe-uninitialized]
> 5152 | rettype = enforce_generic_type_consistency(actual_arg_types,
This code is ~18 years old, so I'm dubious there's a real problem here.
Does something like this suppress the warning?
Oid actual_arg_types[FUNC_MAX_ARGS] = {InvalidOid};
--
nathan
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: PG19beta1: GCC 16.1.1 warning: ‘actual_arg_types’ may be used uninitialized in clauses.c
@ 2026-06-04 22:24 Tristan Partin <tristan@partin.io>
parent: Nathan Bossart <nathandbossart@gmail.com>
1 sibling, 0 replies; 5+ messages in thread
From: Tristan Partin @ 2026-06-04 22:24 UTC (permalink / raw)
To: Nathan Bossart <nathandbossart@gmail.com>; +Cc: pgsql-hackers; Hans Buschmann <buschmann@nidsa.net>
On Thu Jun 4, 2026 at 3:08 PM UTC, Nathan Bossart wrote:
> On Thu, Jun 04, 2026 at 02:42:18PM +0000, Hans Buschmann wrote:
>> 839/2360] Compiling C object src/backend/postgres_lib.a.p/optimizer_util_clauses.c.o
>> ../src/backend/optimizer/util/clauses.c: In function ‘recheck_cast_function_args.isra’:
>> ../src/backend/optimizer/util/clauses.c:5152:19: warning: ‘actual_arg_types’ may be used uninitialized [-Wmaybe-uninitialized]
>> 5152 | rettype = enforce_generic_type_consistency(actual_arg_types,
>
> This code is ~18 years old, so I'm dubious there's a real problem here.
Pulling the code into the email:
> static void
> recheck_cast_function_args(List *args, Oid result_type,
> Oid *proargtypes, int pronargs,
> HeapTuple func_tuple)
> {
> [...]
> Oid actual_arg_types[FUNC_MAX_ARGS];
> [...]
> ListCell *lc;
>
> if (list_length(args) > FUNC_MAX_ARGS)
> elog(ERROR, "too many function arguments");
> nargs = 0;
> foreach(lc, args)
> {
> actual_arg_types[nargs++] = exprType((Node *) lfirst(lc));
> }
> Assert(nargs == pronargs);
> memcpy(declared_arg_types, proargtypes, pronargs * sizeof(Oid));
> rettype = enforce_generic_type_consistency(actual_arg_types,
GCC seems right to complain. A NIL list or a list with a length of 0
would initialize none of the elements in actual_arg_types. However, is
this a problem in actuality? No, because we use nargs to make sure we
don't access uninitialized memory in
enforce_generic_type_consistency(). Maybe GCC's static analysis is a lot
smarter than I give it credit for though, and this is a compiler bug in
the newer version.
> Does something like this suppress the warning?
>
> Oid actual_arg_types[FUNC_MAX_ARGS] = {InvalidOid};
I could not reproduce on 16.1.0 via nixpkgs or 16.1.1 on Fedora 44
(which is strange), but theoretically this would work.
--
Tristan Partin
PostgreSQL Contributors Team
AWS (https://aws.amazon.com)
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: PG19beta1: GCC 16.1.1 warning: ‘actual_arg_types’ may be used uninitialized in clauses.c
@ 2026-06-12 14:54 Álvaro Herrera <alvherre@kurilemu.de>
parent: Nathan Bossart <nathandbossart@gmail.com>
1 sibling, 1 reply; 5+ messages in thread
From: Álvaro Herrera @ 2026-06-12 14:54 UTC (permalink / raw)
To: Nathan Bossart <nathandbossart@gmail.com>; +Cc: Hans Buschmann <buschmann@nidsa.net>; pgsql-hackers
On 2026-Jun-04, Nathan Bossart wrote:
> On Thu, Jun 04, 2026 at 02:42:18PM +0000, Hans Buschmann wrote:
> > 839/2360] Compiling C object src/backend/postgres_lib.a.p/optimizer_util_clauses.c.o
> > ../src/backend/optimizer/util/clauses.c: In function ‘recheck_cast_function_args.isra’:
> > ../src/backend/optimizer/util/clauses.c:5152:19: warning: ‘actual_arg_types’ may be used uninitialized [-Wmaybe-uninitialized]
> > 5152 | rettype = enforce_generic_type_consistency(actual_arg_types,
>
> This code is ~18 years old, so I'm dubious there's a real problem here.
> Does something like this suppress the warning?
>
> Oid actual_arg_types[FUNC_MAX_ARGS] = {InvalidOid};
I agree that it doesn't look like there's a real problem, and that
something like what you suggest should silence this warning. I mildly
prefer to do " = {0}" though, the rules for C incomplete initializers
being so weird. But I wouldn't oppose this patch as posted.
BTW we seem to do pretty much the same thing in ParseFuncOrColumn(),
right?
--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
"People get annoyed when you try to debug them." (Larry Wall)
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: PG19beta1: GCC 16.1.1 warning: ‘actual_arg_types’ may be used uninitialized in clauses.c
@ 2026-06-17 14:39 Nathan Bossart <nathandbossart@gmail.com>
parent: Álvaro Herrera <alvherre@kurilemu.de>
0 siblings, 1 reply; 5+ messages in thread
From: Nathan Bossart @ 2026-06-17 14:39 UTC (permalink / raw)
To: Álvaro Herrera <alvherre@kurilemu.de>; +Cc: Hans Buschmann <buschmann@nidsa.net>; pgsql-hackers
On Fri, Jun 12, 2026 at 04:54:04PM +0200, Álvaro Herrera wrote:
> On 2026-Jun-04, Nathan Bossart wrote:
>> This code is ~18 years old, so I'm dubious there's a real problem here.
>> Does something like this suppress the warning?
>>
>> Oid actual_arg_types[FUNC_MAX_ARGS] = {InvalidOid};
>
> I agree that it doesn't look like there's a real problem, and that
> something like what you suggest should silence this warning. I mildly
> prefer to do " = {0}" though, the rules for C incomplete initializers
> being so weird. But I wouldn't oppose this patch as posted.
WFM. Hans, can you confirm this fixes the issue?
--
nathan
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: PG19beta1: GCC 16.1.1 warning: ‘actual_arg_types’ may be used uninitialized in clauses.c
@ 2026-06-17 15:27 Erik Rijkers <er@xs4all.nl>
parent: Nathan Bossart <nathandbossart@gmail.com>
0 siblings, 0 replies; 5+ messages in thread
From: Erik Rijkers @ 2026-06-17 15:27 UTC (permalink / raw)
To: Nathan Bossart <nathandbossart@gmail.com>; Álvaro Herrera <alvherre@kurilemu.de>; +Cc: Hans Buschmann <buschmann@nidsa.net>; pgsql-hackers
Op 6/17/26 om 16:39 schreef Nathan Bossart:
> On Fri, Jun 12, 2026 at 04:54:04PM +0200, Álvaro Herrera wrote:
>> On 2026-Jun-04, Nathan Bossart wrote:
>>> This code is ~18 years old, so I'm dubious there's a real problem here.
>>> Does something like this suppress the warning?
>>>
>>> Oid actual_arg_types[FUNC_MAX_ARGS] = {InvalidOid};
>>
>> I agree that it doesn't look like there's a real problem, and that
>> something like what you suggest should silence this warning. I mildly
>> prefer to do " = {0}" though, the rules for C incomplete initializers
>> being so weird. But I wouldn't oppose this patch as posted.
>
> WFM. Hans, can you confirm this fixes the issue?
>
FWIW, it silences that warning on my gcc 16.1.0
Erik
^ permalink raw reply [nested|flat] 5+ messages in thread
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2026-06-04 15:07 Re: PG19beta1: GCC 16.1.1 warning: ‘actual_arg_types’ may be used uninitialized in clauses.c Nathan Bossart <nathandbossart@gmail.com>
2026-06-04 22:24 ` Tristan Partin <tristan@partin.io>
2026-06-12 14:54 ` Álvaro Herrera <alvherre@kurilemu.de>
2026-06-17 14:39 ` Nathan Bossart <nathandbossart@gmail.com>
2026-06-17 15:27 ` Erik Rijkers <er@xs4all.nl>
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