Suggested-by: Eric Blake <ebl...@redhat.com>
Signed-off-by: Markus Armbruster <arm...@redhat.com>
Reviewed-by: Eric Blake <ebl...@redhat.com>
Message-Id: <1447776349-2344-1-git-send-email-arm...@redhat.com>
---
include/qapi/error.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/include/qapi/error.h b/include/qapi/error.h
index 6285cf5..1480f59 100644
--- a/include/qapi/error.h
+++ b/include/qapi/error.h
@@ -76,6 +76,23 @@
* But when all you do with the error is pass it on, please use
* foo(arg, errp);
* for readability.
+ *
+ * Receive and accumulate multiple errors (first one wins):
+ * Error *err = NULL, *local_err = NULL;
+ * foo(arg, &err);
+ * bar(arg, &local_err);
+ * error_propagate(&err, local_err);
+ * if (err) {
+ * handle the error...
+ * }
+ *
+ * Do *not* "optimize" this to
+ * foo(arg, &err);
+ * bar(arg, &err); // WRONG!
+ * if (err) {
+ * handle the error...
+ * }
+ * because this may pass a non-null err to bar().
*/
#ifndef ERROR_H
--
2.4.3
