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

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Feb 07, 2020 at 02:04:53PM +0100, Philippe Mathieu-Daudé wrote:
> 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>

Is it really worth adding counting logic just so we can assert?
There are a bunch of other places that deal with
default, like qmp query machines and find_default_machine.

> ---
>  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