[PATCH] c: [PR104822] Don't warn about converting NULL to different sso endian

[PATCH] c: [PR104822] Don't warn about converting NULL to different sso endian

[Andrew Pinski]

In a similar way we don't warn about NULL pointer constant conversion to
a different named address we should not warn to a different sso endian
either.
This adds the simple check.

Bootstrapped and tested on x86_64-linux-gnu with no regressions.

	PR c/104822

gcc/c/ChangeLog:

	* c-typeck.cc (convert_for_assignment): Check for null pointer
	before warning about an incompatible scalar storage order.

gcc/testsuite/ChangeLog:

	* gcc.dg/sso-18.c: New test.
---
 gcc/c/c-typeck.cc             |  1 +
 gcc/testsuite/gcc.dg/sso-18.c | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/sso-18.c

diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 6e044b4afbc..f39dc71d593 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -7449,6 +7449,7 @@ convert_for_assignment (location_t location, location_t expr_loc, tree type,
 
       /* See if the pointers point to incompatible scalar storage orders.  */
       if (warn_scalar_storage_order
+	  && !null_pointer_constant_p (rhs)
 	  && (AGGREGATE_TYPE_P (ttl) && TYPE_REVERSE_STORAGE_ORDER (ttl))
 	     != (AGGREGATE_TYPE_P (ttr) && TYPE_REVERSE_STORAGE_ORDER (ttr)))
 	{
diff --git a/gcc/testsuite/gcc.dg/sso-18.c b/gcc/testsuite/gcc.dg/sso-18.c
new file mode 100644
index 00000000000..799a0c858f2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/sso-18.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* PR c/104822 */
+
+#include <stddef.h>
+
+struct Sb {
+  int i;
+} __attribute__((scalar_storage_order("big-endian")));
+struct Sl {
+  int i;
+} __attribute__((scalar_storage_order("little-endian")));
+
+/* Neither of these should warn about incompatible scalar storage order
+   as NULL pointers are compatiable with both endian. */
+struct Sb *pb = NULL; /* { dg-bogus "" } */
+struct Sl *pl = NULL; /* { dg-bogus "" } */
-- 
2.39.3

Re: [PATCH] c: [PR104822] Don't warn about converting NULL to different sso endian

[Marek Polacek]

On Thu, Oct 19, 2023 at 08:37:31AM -0700, Andrew Pinski wrote:
> In a similar way we don't warn about NULL pointer constant conversion to
> a different named address we should not warn to a different sso endian
> either.
> This adds the simple check.
> 
> Bootstrapped and tested on x86_64-linux-gnu with no regressions.

Looks good, but please put "[PR104822]" at the end of the subject line.
 
> 	PR c/104822
> 
> gcc/c/ChangeLog:
> 
> 	* c-typeck.cc (convert_for_assignment): Check for null pointer
> 	before warning about an incompatible scalar storage order.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.dg/sso-18.c: New test.
> ---
>  gcc/c/c-typeck.cc             |  1 +
>  gcc/testsuite/gcc.dg/sso-18.c | 16 ++++++++++++++++
>  2 files changed, 17 insertions(+)
>  create mode 100644 gcc/testsuite/gcc.dg/sso-18.c
> 
> diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
> index 6e044b4afbc..f39dc71d593 100644
> --- a/gcc/c/c-typeck.cc
> +++ b/gcc/c/c-typeck.cc
> @@ -7449,6 +7449,7 @@ convert_for_assignment (location_t location, location_t expr_loc, tree type,
>  
>        /* See if the pointers point to incompatible scalar storage orders.  */
>        if (warn_scalar_storage_order
> +	  && !null_pointer_constant_p (rhs)
>  	  && (AGGREGATE_TYPE_P (ttl) && TYPE_REVERSE_STORAGE_ORDER (ttl))
>  	     != (AGGREGATE_TYPE_P (ttr) && TYPE_REVERSE_STORAGE_ORDER (ttr)))
>  	{
> diff --git a/gcc/testsuite/gcc.dg/sso-18.c b/gcc/testsuite/gcc.dg/sso-18.c
> new file mode 100644
> index 00000000000..799a0c858f2
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/sso-18.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* PR c/104822 */
> +
> +#include <stddef.h>
> +
> +struct Sb {
> +  int i;
> +} __attribute__((scalar_storage_order("big-endian")));
> +struct Sl {
> +  int i;
> +} __attribute__((scalar_storage_order("little-endian")));
> +
> +/* Neither of these should warn about incompatible scalar storage order
> +   as NULL pointers are compatiable with both endian. */
> +struct Sb *pb = NULL; /* { dg-bogus "" } */
> +struct Sl *pl = NULL; /* { dg-bogus "" } */

Maybe test nullptr as well?

Marek