Collin Funk <[email protected]> writes:
> I pushed the attached patch to silence this warning:
>
> $ gnulib-tool --create-testdir --dir testdir1 regex
> $ cd testdir1
> $ ./configure CFLAGS='-Wzero-as-null-pointer-constant'
> $ make
> [...]
> gcc -DHAVE_CONFIG_H -I. -I.. -DGNULIB_STRICT_CHECKING=1
> -Wzero-as-null-pointer-constant -MT regex.o -MD -MP -MF $depbase.Tpo -c -o
> regex.o regex.c &&\
> mv -f $depbase.Tpo $depbase.Po
> In file included from regex.c:72:
> regexec.c: In function ‘merge_state_with_log’:
> regexec.c:2344:40: warning: zero as null pointer constant
> [-Wzero-as-null-pointer-constant]
> 2344 | else if (mctx->state_log[cur_idx] == 0)
> |
> [...]
>
> The 'git blame' shows the code is many years old. I just only noticed it
> now since we began replacing glibc's regex.
Here is another one:
$ gnulib-tool --create-testdir --dir testdir1 readutmp
$ cd testdir1
$ ./configure --enable-systemd CFLAGS='-Wzero-as-null-pointer-constant'
$ make
[...]
gcc -DHAVE_CONFIG_H -I. -I.. -DGNULIB_STRICT_CHECKING=1
-Wzero-as-null-pointer-constant -MT readutmp.o -MD -MP -MF .deps/readutmp.Tpo
-c -o readutmp.o readutmp.c
readutmp.c: In function ‘read_utmp_from_systemd’:
readutmp.c:801:26: warning: zero as null pointer constant
[-Wzero-as-null-pointer-constant]
801 | struct utmp_alloc a = {0};
| ^
[...]
I was tempted to not fix it since {0} is a convenient way to zero all
the struct members. However, I see Bruno changed another instance of
this initialization in lib/readutmp.c in commit
f3d96537413f1fc0913cd290b1eea35386295b1b. However, this one was hidden
behind --enable-systemd.
Pushed the attached patch to silence it.
Collin
>From d8d9e3289f51b074b9df0fed52e3b3868683f83e Mon Sep 17 00:00:00 2001
Message-ID: <d8d9e3289f51b074b9df0fed52e3b3868683f83e.1776566950.git.collin.fu...@gmail.com>
From: Collin Funk <[email protected]>
Date: Sat, 18 Apr 2026 19:42:21 -0700
Subject: [PATCH] readutmp: Silence -Wzero-as-null-pointer-constant warning.
* lib/readutmp.c (read_utmp_from_systemd): Initialize all of the struct
members and use NULL for the pointer.
---
ChangeLog | 6 ++++++
lib/readutmp.c | 2 +-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/ChangeLog b/ChangeLog
index 39529954bc..14a27b0c21 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2026-04-18 Collin Funk <[email protected]>
+
+ readutmp: Silence -Wzero-as-null-pointer-constant warning.
+ * lib/readutmp.c (read_utmp_from_systemd): Initialize all of the struct
+ members and use NULL for the pointer.
+
2026-04-16 Collin Funk <[email protected]>
regex: Silence -Wzero-as-null-pointer-constant warning.
diff --git a/lib/readutmp.c b/lib/readutmp.c
index 5d84722404..14293f4006 100644
--- a/lib/readutmp.c
+++ b/lib/readutmp.c
@@ -798,7 +798,7 @@ static int
read_utmp_from_systemd (idx_t *n_entries, STRUCT_UTMP **utmp_buf, int options)
{
/* Fill entries, simulating what a utmp file would contain. */
- struct utmp_alloc a = {0};
+ struct utmp_alloc a = { NULL, 0, 0, 0 };
/* Synthesize a BOOT_TIME entry. */
if (!(options & (READ_UTMP_USER_PROCESS | READ_UTMP_NO_BOOT_TIME)))
--
2.53.0
