[PATCH v3 3/3] vl: Abort if multiple machines are registered as default

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

It would be confusing to have multiple default machines.
Abort if this ever occurs.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
v2: Use assert() instead of human friendly message (Marc-André)

Cc: Marc-André Lureau <marcandre.lureau@gmail.com>
Cc: Laurent Vivier <laurent@vivier.eu>
---
 vl.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/vl.c b/vl.c
index 7dcb0879c4..b3e0f7af25 100644
--- a/vl.c
+++ b/vl.c
@@ -2354,6 +2354,8 @@ static MachineClass *machine_parse(const char *name, GSList *machines)
     GSList *el;
 
     if (is_help_option(name)) {
+        int default_count = 0;
+
         printf("Supported machines are:\n");
         machines = g_slist_sort(machines, machine_class_cmp);
         for (el = machines; el; el = el->next) {
@@ -2364,7 +2366,9 @@ static MachineClass *machine_parse(const char *name, GSList *machines)
             printf("%-20s %s%s%s\n", mc->name, mc->desc,
                    mc->is_default ? " (default)" : "",
                    mc->deprecation_reason ? " (deprecated)" : "");
+            default_count += !!mc->is_default;
         }
+        assert(default_count <= 1);
         exit(0);
     }
 
-- 
2.21.1