Re: [PATCH v3 5/7] qapi: Introduce QAPI_LIST_APPEND

[Markus Armbruster <armbru@redhat.com>]

Eric Blake <eblake@redhat.com> writes:

> Similar to the existing QAPI_LIST_PREPEND, but designed for use where
> we want to preserve insertion order.  Callers will be added in
> upcoming patches.  Note the difference in signature: PREPEND takes
> List*, APPEND takes List**.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  include/qapi/util.h | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/include/qapi/util.h b/include/qapi/util.h
> index 6178e98e97a5..8b4967990c0d 100644
> --- a/include/qapi/util.h
> +++ b/include/qapi/util.h
> @@ -37,4 +37,17 @@ int parse_qapi_name(const char *name, bool complete);
>      (list) = _tmp; \
>  } while (0)
>
> +/*
> + * For any pointer to a GenericList @tail, insert @element at the back and
> + * update the tail.
> + *
> + * Note that this macro evaluates @element exactly once, so it is safe
> + * to have side-effects with that argument.
> + */
> +#define QAPI_LIST_APPEND(tail, element) do { \
> +    *(tail) = g_malloc0(sizeof(**(tail))); \
> +    (*(tail))->value = (element); \
> +    (tail) = &(*tail)->next; \
> +} while (0)
> +
>  #endif

You mentioned parenthesizing the lone unparenthesized occurence of
@tail, like

  +    (tail) = &(*(tail))->next; \

Did you decide not to?