[XEN PATCH][for-4.19 v2 8/8] xen/compat: use BUILD_BUG_ON in CHECK_SIZE macros

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

BUILD_BUG_ON is the preferred way to induce a build error
upon statically determined incorrect conditions.

This also fixes a MISRA C:2012 Rule 10.1 violation in the
previous formulation.

Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
---
Changes in v2:
- replace the construct with a BUILD_BUG_ON.
---
 xen/include/xen/compat.h | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/xen/include/xen/compat.h b/xen/include/xen/compat.h
index f2ce5bb3580a..4daa04183eac 100644
--- a/xen/include/xen/compat.h
+++ b/xen/include/xen/compat.h
@@ -151,12 +151,20 @@ CHECK_NAME_(k, n, T)(k xen_ ## n *x, \
     return x == c; \
 }
 
-#define CHECK_SIZE(name) \
-    typedef int CHECK_NAME(name, S)[1 - (sizeof(xen_ ## name ## _t) != \
-                                         sizeof(compat_ ## name ## _t)) * 2]
+#define CHECK_SIZE(name)                                  \
+static inline void __maybe_unused CHECK_SIZE_##name(void) \
+{                                                         \
+    typedef int CHECK_NAME(name, S)[1];                   \
+    BUILD_BUG_ON(sizeof(xen_ ## name ## _t) !=            \
+                 sizeof(compat_ ## name ## _t));          \
+}
 #define CHECK_SIZE_(k, n) \
-    typedef int CHECK_NAME_(k, n, S)[1 - (sizeof(k xen_ ## n) != \
-                                          sizeof(k compat_ ## n)) * 2]
+static inline void __maybe_unused CHECK_SIZE_##k_##n(void) \
+{                                                          \
+    typedef int CHECK_NAME_(k, n, S)[1];                   \
+    BUILD_BUG_ON(sizeof(k xen_ ## n) !=                    \
+                 sizeof(k compat_ ## n));                  \
+}
 
 #define CHECK_FIELD_COMMON(name, t, f) \
 static inline int __maybe_unused name(xen_ ## t ## _t *x, compat_ ## t ## _t 
*c) \
-- 
2.34.1