[PATCH] sparse: allow '{ 0 }' to be used without warnings

[PATCH] sparse: allow '{ 0 }' to be used without warnings

[Luc Van Oostenryck]

In standard C, '{ 0 }' can be used as an universal zero-initializer.
However, Sparse complains if this is used on a type where the first
member (possibly nested) is a pointer since Sparse purposely wants
to warn when '0' is used to initialize a pointer type.

Legitimaly, it's desirable to be able to use '{ 0 }' as an idom
without these warnings [1,2].

An option have now been added to Sparse to turn off such warnings.
So, add this option to the SPARSE_FLAGS variable.

[1] https://lore.kernel.org/r/e6796c60-a870-e761-3b07-b680f934c537@ramsayjones.plus.com
[2] https://lore.kernel.org/r/xmqqd07xem9l.fsf@gitster.c.googlers.com

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 3d3a39fc19..69f065ef8c 100644
--- a/Makefile
+++ b/Makefile
@@ -1189,7 +1189,7 @@ PTHREAD_CFLAGS =
 
 # For the 'sparse' target
 SPARSE_FLAGS ?=
-SP_EXTRA_FLAGS =
+SP_EXTRA_FLAGS = -Wno-universal-initializer
 
 # For the 'coccicheck' target; setting SPATCH_BATCH_SIZE higher will
 # usually result in less CPU usage at the cost of higher peak memory.
-- 
2.26.2

Re: [PATCH] sparse: allow '{ 0 }' to be used without warnings

[Eric Sunshine]

On Thu, May 21, 2020 at 5:46 PM Luc Van Oostenryck
<luc.vanoostenryck@gmail.com> wrote:
> In standard C, '{ 0 }' can be used as an universal zero-initializer.
> However, Sparse complains if this is used on a type where the first
> member (possibly nested) is a pointer since Sparse purposely wants
> to warn when '0' is used to initialize a pointer type.
>
> Legitimaly, it's desirable to be able to use '{ 0 }' as an idom
> without these warnings [1,2].

s/idom/idiom/

> An option have now been added to Sparse to turn off such warnings.
> So, add this option to the SPARSE_FLAGS variable.

Do you have a reference to the commit or Sparse release notes which
mention this new option? It might be nice to include it here in the
commit message. Also, should this minimum Sparse version be mentioned
somewhere in documentation so that people invoking the "sparse"
makefile target aren't greeted with an error about
-Wno-universal-initializer being an unrecognized option (assuming that
older Sparse would complain about it)?

> [1] https://lore.kernel.org/r/e6796c60-a870-e761-3b07-b680f934c537@ramsayjones.plus.com
> [2] https://lore.kernel.org/r/xmqqd07xem9l.fsf@gitster.c.googlers.com
>
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>

Re: [PATCH] sparse: allow '{ 0 }' to be used without warnings

[Junio C Hamano]

Eric Sunshine <sunshine@sunshineco.com> writes:

> Do you have a reference to the commit or Sparse release notes which
> mention this new option? It might be nice to include it here in the
> commit message. Also, should this minimum Sparse version be mentioned
> somewhere in documentation so that people invoking the "sparse"
> makefile target aren't greeted with an error about
> -Wno-universal-initializer being an unrecognized option (assuming that
> older Sparse would complain about it)?

Both sensible considerations.  Thanks for bringing them up.

>
>> [1] https://lore.kernel.org/r/e6796c60-a870-e761-3b07-b680f934c537@ramsayjones.plus.com
>> [2] https://lore.kernel.org/r/xmqqd07xem9l.fsf@gitster.c.googlers.com
>>
>> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>