[PATCH v2] sparse: allow '{ 0 }' to be used without warnings

[PATCH v2] 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 idiom
without these warnings [1,2]. To allow this, an option have now
been added to Sparse:
    537e3e2dae univ-init: conditionally accept { 0 } without warnings

So, add this option to the SPARSE_FLAGS variable.

Note: The option have just been added to Sparse. So, to benefit
      now from this patch it's needed to use the latest Sparse
      source from kernel.org. The option will simply be ignored
      by older versions of Sparse.

[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>
---

Change since v1:
* adapt the commit message to:
  - fix a typo
  - give a reference to the Spatch patch
  - add a note telling the latest Sparse source is needed to
    benefit from the patch but older versions won't complain.

 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 v2] sparse: allow '{ 0 }' to be used without warnings

[Junio C Hamano]

Luc Van Oostenryck <luc.vanoostenryck@gmail.com> writes:

> Note: The option have just been added to Sparse. So, to benefit
>       now from this patch it's needed to use the latest Sparse
>       source from kernel.org. The option will simply be ignored
>       by older versions of Sparse.

The last sentence in this paragraph is very very much appreciated
;-)

>
> [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>
> ---
>
> Change since v1:
> * adapt the commit message to:
>   - fix a typo
>   - give a reference to the Spatch patch
>   - add a note telling the latest Sparse source is needed to
>     benefit from the patch but older versions won't complain.
>
>  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.

Re: [PATCH v2] sparse: allow '{ 0 }' to be used without warnings

[Luc Van Oostenryck]

Hi Junio,

I've now changed Sparse's default to not warn when using '{ 0 }'.
This flag is thus now unneeded for Git and can be dropped
(but it won't hurt to keep it).

-- Luc

Re: [PATCH v2] sparse: allow '{ 0 }' to be used without warnings

[Junio C Hamano]

Luc Van Oostenryck <luc.vanoostenryck@gmail.com> writes:

> I've now changed Sparse's default to not warn when using '{ 0 }'.
> This flag is thus now unneeded for Git and can be dropped
> (but it won't hurt to keep it).

Nice.  Thanks.