On 9 Mar 2022, at 17:10, Adrian Moreno wrote:
> Having both LONG and SHORT versions of the SAFE macros with different
> names is not very convenient. Add helpers that facilitate overloading
> such macros using a single name.
>
> In order to work around a known issue in MSVC [1], an indirection layer
> has to be introduced.
>
> [1]
> https://developercommunity.visualstudio.com/t/-va-args-seems-to-be-trated-as-a-single-parameter/460154
>
> Acked-by: Dumitru Ceara <[email protected]>
> Signed-off-by: Adrian Moreno <[email protected]>
> ---
This looks good to me!
Acked-by: Eelco Chaudron <[email protected]>
Small nit, do we need to update the date in the copyright notice? I keep
forgetting if we do or do not. But I guess not, as I do not see it in other
files.
> include/openvswitch/util.h | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/include/openvswitch/util.h b/include/openvswitch/util.h
> index 157f8cecd..8184dd3d3 100644
> --- a/include/openvswitch/util.h
> +++ b/include/openvswitch/util.h
> @@ -268,6 +268,27 @@ OVS_NO_RETURN void ovs_assert_failure(const char *,
> const char *, const char *);
> #define UPDATE_MULTIVAR_SAFE_LONG(VAR, NEXT_VAR)
> \
> UPDATE_MULTIVAR(VAR, ITER_VAR(NEXT_VAR))
>
> +/* Helpers to allow overloading the *_SAFE iterator macros and select either
> + * the LONG or the SHORT version depending on the number of arguments.
> + */
> +#define GET_SAFE_MACRO2(_1, _2, NAME, ...) NAME
> +#define GET_SAFE_MACRO3(_1, _2, _3, NAME, ...) NAME
> +#define GET_SAFE_MACRO4(_1, _2, _3, _4, NAME, ...) NAME
> +#define GET_SAFE_MACRO5(_1, _2, _3, _4, _5, NAME, ...) NAME
> +#define GET_SAFE_MACRO6(_1, _2, _3, _4, _5, _6, NAME, ...) NAME
> +#define GET_SAFE_MACRO(MAX_ARGS) GET_SAFE_MACRO ## MAX_ARGS
> +
> +/* MSVC treats __VA_ARGS__ as a simple token in argument lists. Introduce
> + * a level of indirection to work around that. */
> +#define EXPAND_MACRO(name, args) name args
> +
> +/* Overload the LONG and the SHORT version of the macros. MAX_ARGS is the
> + * maximum number of arguments (i.e: the number of arguments of the LONG
> + * version). */
> +#define OVERLOAD_SAFE_MACRO(LONG, SHORT, MAX_ARGS, ...) \
> + EXPAND_MACRO(GET_SAFE_MACRO(MAX_ARGS), \
> + (__VA_ARGS__, LONG, SHORT))(__VA_ARGS__)
> +
> /* Returns the number of elements in ARRAY. */
> #define ARRAY_SIZE(ARRAY) __ARRAY_SIZE(ARRAY)
>
> --
> 2.34.1
>
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