Hi,
On Tue, Jan 20, 2026 at 08:54:18AM +0100, Peter Eisentraut wrote:
> This patch fixes cases where a qualifier (const, in all cases here) was
> dropped by a cast, but the cast was otherwise necessary or desirable, so the
> straightforward fix is to add the qualifier into the cast.
>
> This was checked with gcc -Wcast-qual, but it doesn't fix all such warnings,
> only the trivially fixable ones.
diff --git a/src/include/varatt.h b/src/include/varatt.h
index eccd3ca04d6..03e9d1869aa 100644
--- a/src/include/varatt.h
+++ b/src/include/varatt.h
It looks like those changes produce:
../../../src/include/varatt.h: In function ‘VARDATA’:
../../../src/include/varatt.h:261:33: warning: return discards ‘const’
qualifier from pointer target type [-Wdiscarded-qualifiers]
261 | #define VARDATA_4B(PTR) (((const varattrib_4b *)
(PTR))->va_4byte.va_data)
| ^
../../../src/include/varatt.h:307:16: note: in expansion of macro ‘VARDATA_4B’
307 | return VARDATA_4B(PTR);
| ^~~~~~~~~~
../../../src/include/varatt.h: In function ‘VARDATA_SHORT’:
../../../src/include/varatt.h:263:33: warning: return discards ‘const’
qualifier from pointer target type [-Wdiscarded-qualifiers]
263 | #define VARDATA_1B(PTR) (((const varattrib_1b *)
(PTR))->va_data)
| ^
../../../src/include/varatt.h:321:16: note: in expansion of macro ‘VARDATA_1B’
321 | return VARDATA_1B(PTR);
| ^~~~~~~~~~
../../../src/include/varatt.h: In function ‘VARDATA_EXTERNAL’:
../../../src/include/varatt.h:264:33: warning: return discards ‘const’
qualifier from pointer target type [-Wdiscarded-qualifiers]
264 | #define VARDATA_1B_E(PTR) (((const varattrib_1b_e *)
(PTR))->va_data)
| ^
../../../src/include/varatt.h:342:16: note: in expansion of macro ‘VARDATA_1B_E’
342 | return VARDATA_1B_E(PTR);
| ^~~~~~~~~~~~
../../../src/include/varatt.h: In function ‘VARDATA_ANY’:
../../../src/include/varatt.h:488:52: warning: return discards ‘const’
qualifier from pointer target type [-Wdiscarded-qualifiers]
488 | return VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR);
as they are still used by functions that return non const:
"
static inline char *
VARDATA(const void *PTR)
{
return VARDATA_4B(PTR);
}
"
> - RangeType *r1 = *(RangeType **) key1;
> - RangeType *r2 = *(RangeType **) key2;
> + RangeType *r1 = *(RangeType *const *) key1;
> + RangeType *r2 = *(RangeType *const *) key2;
That's correct. My improved cocci script [1] would incorrectly produce:
- RangeType *r1 = *(RangeType **) key1;
- RangeType *r2 = *(RangeType **) key2;
+ RangeType *r1 = *(const RangeType **)key1;
+ RangeType *r2 = *(const RangeType **)key2;
Same for:
> - file_entry_t *fa = *((file_entry_t **) a);
> - file_entry_t *fb = *((file_entry_t **) b);
> + file_entry_t *fa = *((file_entry_t *const *) a);
> + file_entry_t *fb = *((file_entry_t *const *) b);
>
>
Same for:
> - Step *stepa = *((Step **) a);
> - Step *stepb = *((Step **) b);
> + Step *stepa = *((Step *const *) a);
> + Step *stepb = *((Step *const *) b);
>
> - Step *step = *((Step **) b);
> + Step *step = *((Step *const *) b);
>
> diff --git a/src/test/modules/libpq_pipeline/libpq_pipeline.c
> b/src/test/modules/libpq_pipeline/libpq_pipeline.c
> index 03371721460..4a9bb65b9bb 100644
> --- a/src/test/modules/libpq_pipeline/libpq_pipeline.c
> +++ b/src/test/modules/libpq_pipeline/libpq_pipeline.c
> @@ -1576,7 +1576,7 @@ test_singlerowmode(PGconn *conn)
> "SELECT
> generate_series(42, $1)",
> 1,
> NULL,
> - (const char **) param,
> + (const char *const *)
> param,
> NULL,
> NULL,
> 0) != 1)
Correct, also according to:
"
int
PQsendQueryParams(PGconn *conn,
const char *command,
int nParams,
const Oid *paramTypes,
const char *const *paramValues,
const int *paramLengths,
const int *paramFormats,
int resultFormat)
{
"
Also [1], detected a few more trivially fixable ones (see attached).
[1]:
https://github.com/bdrouvot/coccinelle_on_pg/blob/main/misc/search_const_away.cocci
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
>From 9712e7530997e3927b1d27a9b2f981f1c1b23499 Mon Sep 17 00:00:00 2001
From: Bertrand Drouvot <[email protected]>
Date: Tue, 20 Jan 2026 10:57:27 +0000
Subject: [PATCH v1] More Fix accidentally cast away qualifiers
---
src/backend/access/spgist/spgquadtreeproc.c | 8 ++++----
src/common/unicode/case_test.c | 2 +-
2 files changed, 5 insertions(+), 5 deletions(-)
66.9% src/backend/access/spgist/
33.0% src/common/unicode/
diff --git a/src/backend/access/spgist/spgquadtreeproc.c
b/src/backend/access/spgist/spgquadtreeproc.c
index 1b907d9186b..430e802cf80 100644
--- a/src/backend/access/spgist/spgquadtreeproc.c
+++ b/src/backend/access/spgist/spgquadtreeproc.c
@@ -145,8 +145,8 @@ spg_quad_choose(PG_FUNCTION_ARGS)
static int
x_cmp(const void *a, const void *b, void *arg)
{
- Point *pa = *(Point **) a;
- Point *pb = *(Point **) b;
+ Point *pa = *(Point *const *) a;
+ Point *pb = *(Point *const *) b;
if (pa->x == pb->x)
return 0;
@@ -156,8 +156,8 @@ x_cmp(const void *a, const void *b, void *arg)
static int
y_cmp(const void *a, const void *b, void *arg)
{
- Point *pa = *(Point **) a;
- Point *pb = *(Point **) b;
+ Point *pa = *(Point *const *) a;
+ Point *pb = *(Point *const *) b;
if (pa->y == pb->y)
return 0;
diff --git a/src/common/unicode/case_test.c b/src/common/unicode/case_test.c
index 2144219e178..fb159c1c27c 100644
--- a/src/common/unicode/case_test.c
+++ b/src/common/unicode/case_test.c
@@ -55,7 +55,7 @@ initcap_wbnext(void *state)
while (wbstate->offset < wbstate->len &&
wbstate->str[wbstate->offset] != '\0')
{
- char32_t u = utf8_to_unicode((unsigned char *)
wbstate->str +
+ char32_t u = utf8_to_unicode((const unsigned char *)
wbstate->str +
wbstate->offset);
bool curr_alnum = pg_u_isalnum(u, wbstate->posix);
--
2.34.1
