Re: [PATCH] qapi: enable use of g_autoptr with QAPI types

[Markus Armbruster]

Daniel P. Berrangé <berrange@redhat.com> writes:

> On Thu, Jul 23, 2020 at 06:49:44AM -0500, Eric Blake wrote:
>> On 7/23/20 6:12 AM, Daniel P. Berrangé wrote:
>> > Currently QAPI generates a type and function for free'ing it:
>> > 
>> >    typedef struct QCryptoBlockCreateOptions QCryptoBlockCreateOptions;
>> >    void qapi_free_QCryptoBlockCreateOptions(QCryptoBlockCreateOptions 
>> > *obj);
>> > 
>> 
>> > The above code example now becomes
>> > 
>> >    g_autoptr(QCryptoBlockCreateOptions) opts = NULL;
>> > 
>> >    opts = g_new0(QCryptoBlockCreateOptions, 1);
>> > 
>> >    ....do stuff with opts...
>> > 
>> > Note, if the local pointer needs to live beyond the scope holding the
>> > variable, then g_steal_pointer can be used. This is useful to return the
>> > pointer to the caller in the success codepath, while letting it be freed
>> > in all error codepaths.
>> > 
>> >    return g_steal_pointer(&opts);
>> > 
>> 
>> Yep, the idea makes sense!

Agree.

>> > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
>> > ---
>> >   include/crypto/block.h | 2 --
>> >   scripts/qapi/types.py  | 1 +
>> >   2 files changed, 1 insertion(+), 2 deletions(-)
>> 
>> Missing a counterpart change to docs/devel/qapi-code-gen.txt.

Yes.  Can do that in my tree.

>>                                                                And it might
>> be nice to make this a series with at least one followup patch using the new
>> capability, or at least so 'make check' coverage.  But otherwise on the
>> right track.
>
> The crypto/block.c already makes use of this capability, which is why
> I had to remove the line from block.h to avoid declaring the same thing
> twice !

Could be mentioned in the commit message.

Still, using it somewhere in tests would be nice.
test-qobject-input-visitor.c's test_visitor_in_struct_nested() looks
trivial to convert.  Feel free to pick something else.

In case you prefer not to, with a qapi-code-gen.txt update:
Reviewed-by: Markus Armbruster <armbru@redhat.com>