[PATCH v2 3/3] clang: don't define nocall

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Clang doesn't support attribute error, and the possible equivalents
like diagnose_if don't seem to work well in this case as they trigger
when when the function is not called (just by being used by the
APPEND_CALL macro).

Define nocall to a noop on clang until a proper solution can be found.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/include/xen/compiler.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h
index c22439b7a4..225e09e5f7 100644
--- a/xen/include/xen/compiler.h
+++ b/xen/include/xen/compiler.h
@@ -20,7 +20,11 @@
 
 #define __weak        __attribute__((__weak__))
 
-#define nocall        __attribute__((error("Nonstandard ABI")))
+#if !defined(__clang__)
+# define nocall        __attribute__((error("Nonstandard ABI")))
+#else
+# define nocall
+#endif
 
 #if (!defined(__clang__) && (__GNUC__ == 4) && (__GNUC_MINOR__ < 5))
 #define unreachable() do {} while (1)
-- 
2.26.2