[PATCH for-4.19? 3/6] xen/macros: Introduce BUILD_ERROR()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

... and use it in self-tests.h.

This is intended to replace constructs such as __bitop_bad_size().  It
produces a better diagnostic, and is MISRA-friendly.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
CC: Michal Orzel <michal.orzel@xxxxxxx>
CC: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

RFC for-4.19.  This can be used to not introduce new MISRA violations when
adjusting __bitop_bad_size().  It's safe to pull out of this series.

---
 xen/include/xen/macros.h     | 2 ++
 xen/include/xen/self-tests.h | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/include/xen/macros.h b/xen/include/xen/macros.h
index ec89f4654fcf..8441d7e7d66a 100644
--- a/xen/include/xen/macros.h
+++ b/xen/include/xen/macros.h
@@ -59,6 +59,8 @@
 #define BUILD_BUG_ON(cond) ((void)BUILD_BUG_ON_ZERO(cond))
 #endif
 
+#define BUILD_ERROR(msg) asm ( ".error \"" msg "\"" )
+
 /* Hide a value from the optimiser. */
 #define HIDE(x)                                 \
     ({                                          \
diff --git a/xen/include/xen/self-tests.h b/xen/include/xen/self-tests.h
index 42a4cc4d17fe..4bc322b7f2a6 100644
--- a/xen/include/xen/self-tests.h
+++ b/xen/include/xen/self-tests.h
@@ -22,9 +22,9 @@
         typeof(fn(val)) real = fn(val);                                 \
                                                                         \
         if ( !__builtin_constant_p(real) )                              \
-            asm ( ".error \"'" STR(fn(val)) "' not compile-time constant\"" ); 
\
+            BUILD_ERROR("'" STR(fn(val)) "' not compile-time constant"); \
         else if ( real != res )                                         \
-            asm ( ".error \"Compile time check '" STR(fn(val) == res) "' 
failed\"" ); \
+            BUILD_ERROR("Compile time check '" STR(fn(val) == res) "' 
failed"); \
     } while ( 0 )
 #else
 #define COMPILE_CHECK(fn, val, res)
-- 
2.39.2