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

[Laurent Vivier <laurent@vivier.eu>]

Le 07/02/2020 à 12:28, Laurent Vivier a écrit :
> Le 07/02/2020 à 12:25, Philippe Mathieu-Daudé a écrit :
>> On 2/7/20 12:08 PM, Laurent Vivier wrote:
>>> Le 07/02/2020 à 12:02, Philippe Mathieu-Daudé a écrit :
>>>> It would be confusing to have multiple default machines.
>>>> Abort if this ever occurs.
>>>>
>>>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>>>> ---
>>>>   vl.c | 7 +++++++
>>>>   1 file changed, 7 insertions(+)
>>>>
>>>> diff --git a/vl.c b/vl.c
>>>> index 7dcb0879c4..da828188eb 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) {
>>>> @@ -2364,6 +2366,11 @@ 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;
>>>> +        }
>>>> +        if (default_count > 1) {
>>>> +            error_printf("Multiple default machines available\n");
>>>> +            abort();
>>>>           }
>>>>           exit(0);
>>>>       }
>>>>
>>>
>>> Does it really deserve an abort?
>>> Ideal solution would be to be able to check this at build or in the unit
>>> tests.
>>
>> This is for developers, not for users. I'll use Marc-André suggestion
>> and use an assertion.
> 
> I agree, but it's why it would be better if it is detected before it
> comes to the user.
> 
> Perhaps you can add a test to run "qemu -h" to trigger the abort() early
> in the develompment process (if it doesn't already exist).

I mean "-M help".

Thanks,
Laurent