[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