Re: [PATCH] block-qdict: Fix -Werror=maybe-uninitialized build failure

2022-03-11 Thread Murilo Opsfelder Araújo 

Hi, Markus.

On 3/11/22 06:33, Markus Armbruster wrote:

Murilo Opsfelder Araujo  writes:


Building QEMU on Fedora 37 (Rawhide Prerelease) ppc64le failed with the
following error:

 $ ../configure --prefix=/usr/local/qemu-disabletcg 
--target-list=ppc-softmmu,ppc64-softmmu --disable-tcg --disable-linux-user
 ...
 $ make -j$(nproc)
 ...
 FAILED: libqemuutil.a.p/qobject_block-qdict.c.o
 cc -m64 -mlittle-endian -Ilibqemuutil.a.p -I. -I.. 
-Isubprojects/libvhost-user -I../subprojects/libvhost-user -Iqapi -Itrace -Iui 
-Iui/shader -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include 
-I/usr/include/sysprof-4 -I/usr/include/lib
 mount -I/usr/include/blkid -I/usr/include/gio-unix-2.0 
-I/usr/include/p11-kit-1 -I/usr/include/pixman-1 -fdiagnostics-color=auto -Wall 
-Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem /root/qemu/linux-headers 
-isystem linux-headers -iquote
  . -iquote /root/qemu -iquote /root/qemu/include -iquote 
/root/qemu/disas/libvixl -pthread -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 
-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes 
-Wredundant-decls -Wundef -Wwrite
 -strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv 
-Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security 
-Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs 
-Wendif-label
 s -Wexpansion-to-defined -Wimplicit-fallthrough=2 
-Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi 
-fstack-protector-strong -fPIE -MD -MQ libqemuutil.a.p/qobject_block-qdict.c.o 
-MF libqemuutil.a.p/qobject_block-qdict.c.o.d -
 o libqemuutil.a.p/qobject_block-qdict.c.o -c ../qobject/block-qdict.c
 In file included from /root/qemu/include/qapi/qmp/qdict.h:16,
  from /root/qemu/include/block/qdict.h:13,
  from ../qobject/block-qdict.c:11:
 /root/qemu/include/qapi/qmp/qobject.h: In function ‘qdict_array_split’:
 /root/qemu/include/qapi/qmp/qobject.h:49:17: error: ‘subqdict’ may be used 
uninitialized [-Werror=maybe-uninitialized]
49 | typeof(obj) _obj = (obj);   \
   | ^~~~
 ../qobject/block-qdict.c:227:16: note: ‘subqdict’ declared here
   227 | QDict *subqdict;
   |^~~~
 cc1: all warnings being treated as errors

Fix build failure by initializing the QDict variable with NULL.

Signed-off-by: Murilo Opsfelder Araujo 
Cc: Kevin Wolf 
Cc: Hanna Reitz 
Cc: Markus Armbruster 
---
  qobject/block-qdict.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c
index 1487cc5dd8..b26524429c 100644
--- a/qobject/block-qdict.c
+++ b/qobject/block-qdict.c
@@ -224,7 +224,7 @@ void qdict_array_split(QDict *src, QList **dst)
  for (i = 0; i < UINT_MAX; i++) {
  QObject *subqobj;
  bool is_subqdict;
-QDict *subqdict;
+QDict *subqdict = NULL;
  char indexstr[32], prefix[32];
  size_t snprintf_ret;


The compiler's warning is actually spurious.  Your patch is the
minimally invasive way to shut it up.  But I wonder whether we can
make the code clearer instead.  Let's have a look:

/*
 * There may be either a single subordinate object (named
 * "%u") or multiple objects (each with a key prefixed "%u."),
 * but not both.
 */
if (!subqobj == !is_subqdict) {
break;

Because of this, ...

}

if (is_subqdict) {

... subqobj is non-null here, and ...

qdict_extract_subqdict(src, , prefix);
assert(qdict_size(subqdict) > 0);
} else {

... null here.

qobject_ref(subqobj);
qdict_del(src, indexstr);
}

qlist_append_obj(*dst, subqobj ?: QOBJECT(subqdict));

What about this:

if (is_subqdict) {
qdict_extract_subqdict(src, , prefix);
assert(qdict_size(subqdict) > 0);
qlist_append_obj(*dst, subqobj);
} else {
qobject_ref(subqobj);
qdict_del(src, indexstr);
qlist_append_obj(*dst, QOBJECT(subqdict));
}



The logic looks inverted but I think I got what you meant.

I've sent a v2 with changes that made the compiler happy and also passed 
check-unit tests.

Thank you!

--
Murilo

Re: [PATCH] block-qdict: Fix -Werror=maybe-uninitialized build failure

2022-03-11 Thread Markus Armbruster 
Murilo Opsfelder Araujo  writes:

> Building QEMU on Fedora 37 (Rawhide Prerelease) ppc64le failed with the
> following error:
>
> $ ../configure --prefix=/usr/local/qemu-disabletcg 
> --target-list=ppc-softmmu,ppc64-softmmu --disable-tcg --disable-linux-user
> ...
> $ make -j$(nproc)
> ...
> FAILED: libqemuutil.a.p/qobject_block-qdict.c.o
> cc -m64 -mlittle-endian -Ilibqemuutil.a.p -I. -I.. 
> -Isubprojects/libvhost-user -I../subprojects/libvhost-user -Iqapi -Itrace 
> -Iui -Iui/shader -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include 
> -I/usr/include/sysprof-4 -I/usr/include/lib
> mount -I/usr/include/blkid -I/usr/include/gio-unix-2.0 
> -I/usr/include/p11-kit-1 -I/usr/include/pixman-1 -fdiagnostics-color=auto 
> -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem 
> /root/qemu/linux-headers -isystem linux-headers -iquote
>  . -iquote /root/qemu -iquote /root/qemu/include -iquote 
> /root/qemu/disas/libvixl -pthread -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 
> -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes 
> -Wredundant-decls -Wundef -Wwrite
> -strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv 
> -Wold-style-declaration -Wold-style-definition -Wtype-limits 
> -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body 
> -Wnested-externs -Wendif-label
> s -Wexpansion-to-defined -Wimplicit-fallthrough=2 
> -Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi 
> -fstack-protector-strong -fPIE -MD -MQ 
> libqemuutil.a.p/qobject_block-qdict.c.o -MF 
> libqemuutil.a.p/qobject_block-qdict.c.o.d -
> o libqemuutil.a.p/qobject_block-qdict.c.o -c ../qobject/block-qdict.c
> In file included from /root/qemu/include/qapi/qmp/qdict.h:16,
>  from /root/qemu/include/block/qdict.h:13,
>  from ../qobject/block-qdict.c:11:
> /root/qemu/include/qapi/qmp/qobject.h: In function ‘qdict_array_split’:
> /root/qemu/include/qapi/qmp/qobject.h:49:17: error: ‘subqdict’ may be 
> used uninitialized [-Werror=maybe-uninitialized]
>49 | typeof(obj) _obj = (obj);   \
>   | ^~~~
> ../qobject/block-qdict.c:227:16: note: ‘subqdict’ declared here
>   227 | QDict *subqdict;
>   |^~~~
> cc1: all warnings being treated as errors
>
> Fix build failure by initializing the QDict variable with NULL.
>
> Signed-off-by: Murilo Opsfelder Araujo 
> Cc: Kevin Wolf 
> Cc: Hanna Reitz 
> Cc: Markus Armbruster 
> ---
>  qobject/block-qdict.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c
> index 1487cc5dd8..b26524429c 100644
> --- a/qobject/block-qdict.c
> +++ b/qobject/block-qdict.c
> @@ -224,7 +224,7 @@ void qdict_array_split(QDict *src, QList **dst)
>  for (i = 0; i < UINT_MAX; i++) {
>  QObject *subqobj;
>  bool is_subqdict;
> -QDict *subqdict;
> +QDict *subqdict = NULL;
>  char indexstr[32], prefix[32];
>  size_t snprintf_ret;

The compiler's warning is actually spurious.  Your patch is the
minimally invasive way to shut it up.  But I wonder whether we can
make the code clearer instead.  Let's have a look:

   /*
* There may be either a single subordinate object (named
* "%u") or multiple objects (each with a key prefixed "%u."),
* but not both.
*/
   if (!subqobj == !is_subqdict) {
   break;

Because of this, ...

   }

   if (is_subqdict) {

... subqobj is non-null here, and ...

   qdict_extract_subqdict(src, , prefix);
   assert(qdict_size(subqdict) > 0);
   } else {

... null here.

   qobject_ref(subqobj);
   qdict_del(src, indexstr);
   }

   qlist_append_obj(*dst, subqobj ?: QOBJECT(subqdict));

What about this:

   if (is_subqdict) {
   qdict_extract_subqdict(src, , prefix);
   assert(qdict_size(subqdict) > 0);
   qlist_append_obj(*dst, subqobj);
   } else {
   qobject_ref(subqobj);
   qdict_del(src, indexstr);
   qlist_append_obj(*dst, QOBJECT(subqdict));
   }

Re: [PATCH] block-qdict: Fix -Werror=maybe-uninitialized build failure

2022-03-10 Thread Daniel Henrique Barboza 




On 3/10/22 17:05, Murilo Opsfelder Araujo wrote:

Building QEMU on Fedora 37 (Rawhide Prerelease) ppc64le failed with the
following error:

 $ ../configure --prefix=/usr/local/qemu-disabletcg 
--target-list=ppc-softmmu,ppc64-softmmu --disable-tcg --disable-linux-user
 ...
 $ make -j$(nproc)
 ...
 FAILED: libqemuutil.a.p/qobject_block-qdict.c.o
 cc -m64 -mlittle-endian -Ilibqemuutil.a.p -I. -I.. 
-Isubprojects/libvhost-user -I../subprojects/libvhost-user -Iqapi -Itrace -Iui 
-Iui/shader -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include 
-I/usr/include/sysprof-4 -I/usr/include/lib
 mount -I/usr/include/blkid -I/usr/include/gio-unix-2.0 
-I/usr/include/p11-kit-1 -I/usr/include/pixman-1 -fdiagnostics-color=auto -Wall 
-Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem /root/qemu/linux-headers 
-isystem linux-headers -iquote
  . -iquote /root/qemu -iquote /root/qemu/include -iquote 
/root/qemu/disas/libvixl -pthread -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 
-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes 
-Wredundant-decls -Wundef -Wwrite
 -strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv 
-Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security 
-Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs 
-Wendif-label
 s -Wexpansion-to-defined -Wimplicit-fallthrough=2 
-Wno-missing-include-dirs -Wno-shift-negative-value -Wno-psabi 
-fstack-protector-strong -fPIE -MD -MQ libqemuutil.a.p/qobject_block-qdict.c.o 
-MF libqemuutil.a.p/qobject_block-qdict.c.o.d -
 o libqemuutil.a.p/qobject_block-qdict.c.o -c ../qobject/block-qdict.c
 In file included from /root/qemu/include/qapi/qmp/qdict.h:16,
  from /root/qemu/include/block/qdict.h:13,
  from ../qobject/block-qdict.c:11:
 /root/qemu/include/qapi/qmp/qobject.h: In function ‘qdict_array_split’:
 /root/qemu/include/qapi/qmp/qobject.h:49:17: error: ‘subqdict’ may be used 
uninitialized [-Werror=maybe-uninitialized]
49 | typeof(obj) _obj = (obj);   \
   | ^~~~
 ../qobject/block-qdict.c:227:16: note: ‘subqdict’ declared here
   227 | QDict *subqdict;
   |^~~~
 cc1: all warnings being treated as errors

Fix build failure by initializing the QDict variable with NULL.

Signed-off-by: Murilo Opsfelder Araujo 
Cc: Kevin Wolf 
Cc: Hanna Reitz 
Cc: Markus Armbruster 
---


Reviewed-by: Daniel Henrique Barboza 


  qobject/block-qdict.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c
index 1487cc5dd8..b26524429c 100644
--- a/qobject/block-qdict.c
+++ b/qobject/block-qdict.c
@@ -224,7 +224,7 @@ void qdict_array_split(QDict *src, QList **dst)
  for (i = 0; i < UINT_MAX; i++) {
  QObject *subqobj;
  bool is_subqdict;
-QDict *subqdict;
+QDict *subqdict = NULL;
  char indexstr[32], prefix[32];
  size_t snprintf_ret;

[PATCH] block-qdict: Fix -Werror=maybe-uninitialized build failure

2022-03-10 Thread Murilo Opsfelder Araujo 
Building QEMU on Fedora 37 (Rawhide Prerelease) ppc64le failed with the
following error:

$ ../configure --prefix=/usr/local/qemu-disabletcg 
--target-list=ppc-softmmu,ppc64-softmmu --disable-tcg --disable-linux-user
...
$ make -j$(nproc)
...
FAILED: libqemuutil.a.p/qobject_block-qdict.c.o
cc -m64 -mlittle-endian -Ilibqemuutil.a.p -I. -I.. 
-Isubprojects/libvhost-user -I../subprojects/libvhost-user -Iqapi -Itrace -Iui 
-Iui/shader -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include 
-I/usr/include/sysprof-4 -I/usr/include/lib
mount -I/usr/include/blkid -I/usr/include/gio-unix-2.0 
-I/usr/include/p11-kit-1 -I/usr/include/pixman-1 -fdiagnostics-color=auto -Wall 
-Winvalid-pch -Werror -std=gnu11 -O2 -g -isystem /root/qemu/linux-headers 
-isystem linux-headers -iquote
 . -iquote /root/qemu -iquote /root/qemu/include -iquote 
/root/qemu/disas/libvixl -pthread -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 
-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes 
-Wredundant-decls -Wundef -Wwrite
-strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv 
-Wold-style-declaration -Wold-style-definition -Wtype-limits -Wformat-security 
-Wformat-y2k -Winit-self -Wignored-qualifiers -Wempty-body -Wnested-externs 
-Wendif-label
s -Wexpansion-to-defined -Wimplicit-fallthrough=2 -Wno-missing-include-dirs 
-Wno-shift-negative-value -Wno-psabi -fstack-protector-strong -fPIE -MD -MQ 
libqemuutil.a.p/qobject_block-qdict.c.o -MF 
libqemuutil.a.p/qobject_block-qdict.c.o.d -
o libqemuutil.a.p/qobject_block-qdict.c.o -c ../qobject/block-qdict.c
In file included from /root/qemu/include/qapi/qmp/qdict.h:16,
 from /root/qemu/include/block/qdict.h:13,
 from ../qobject/block-qdict.c:11:
/root/qemu/include/qapi/qmp/qobject.h: In function ‘qdict_array_split’:
/root/qemu/include/qapi/qmp/qobject.h:49:17: error: ‘subqdict’ may be used 
uninitialized [-Werror=maybe-uninitialized]
   49 | typeof(obj) _obj = (obj);   \
  | ^~~~
../qobject/block-qdict.c:227:16: note: ‘subqdict’ declared here
  227 | QDict *subqdict;
  |^~~~
cc1: all warnings being treated as errors

Fix build failure by initializing the QDict variable with NULL.

Signed-off-by: Murilo Opsfelder Araujo 
Cc: Kevin Wolf 
Cc: Hanna Reitz 
Cc: Markus Armbruster 
---
 qobject/block-qdict.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qobject/block-qdict.c b/qobject/block-qdict.c
index 1487cc5dd8..b26524429c 100644
--- a/qobject/block-qdict.c
+++ b/qobject/block-qdict.c
@@ -224,7 +224,7 @@ void qdict_array_split(QDict *src, QList **dst)
 for (i = 0; i < UINT_MAX; i++) {
 QObject *subqobj;
 bool is_subqdict;
-QDict *subqdict;
+QDict *subqdict = NULL;
 char indexstr[32], prefix[32];
 size_t snprintf_ret;
 
-- 
2.35.1