Re: [Qemu-devel] [PATCH v3 07/18] qapi: Add json output visitor

[Eric Blake]

On 05/18/2016 09:16 AM, Eric Blake wrote:

>>> +static void json_output_type_any(Visitor *v, const char *name, QObject 
>>> **obj,
>>> +                                 Error **errp)
>>> +{
>>> +    JsonOutputVisitor *jov = to_jov(v);
>>> +    QString *str = qobject_to_json(*obj);
>>> +    assert(str);
>>
>> Can't happen.
> 
> Can too.  From tests/check-qobject-json.c:
> 
>         obj = QOBJECT(qstring_from_str(utf8_in));
>         str = qobject_to_json(obj);
>         if (json_out) {
>             g_assert(str);
>             g_assert_cmpstr(qstring_get_str(str), ==, json_out);
>         } else {
>             g_assert(!str);
>         }
> 
> where the failures occur when it is impossible to output proper UTF-8
> due to invalid encoding in a string.

Correction - that test has dead code, because:

        json_out = test_cases[i].json_out ?: test_cases[i].json_in;

so you are right after all - we currently cannot fail on a conversion to
JSON (although the result might not be valid JSON).  At any rate, my
conclusion remains:

>  Arguably, that case would be nicer
> if it could set an Error* (and would make my argument for setting an
> error on Inf/NaN for numbers also a bit more tenable), but that is
> additional work that I haven't tackled yet. I'm trying to get the series
> posted for another round of review, where I've done some major
> reshuffling (such as doing the clone visitor first, not second, in the
> series), so hopefully later today.
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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