[FFmpeg-devel] [PATCH v2] avutil/channel_layout: make pre-defined channel layouts C++ friendly

[James Almer]

On 8/17/2023 11:27 AM, Zhao Zhili wrote:
> From: Zhao Zhili <zhilizhao at tencent.com>
> 
> C++ doesn't support designated initializers until C++20. We have
> a bunch of pre-defined channel layouts, the gains to make them
> usable in C++ exceed the losses.
> 
> Bump minor version so C++ project can check before use these defines.
> 
> Also initialize .opaque field explicitly to reduce warning in C++.
> ---
> v2:
> 1. Keep field names in comments.
> 2. Bump minor version.
> 3. Add comments so it won't be reverted by accident.
> 
>   libavutil/channel_layout.h | 5 +++--
>   libavutil/version.h        | 4 ++--
>   2 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/libavutil/channel_layout.h b/libavutil/channel_layout.h
> index f345415c55..f019b3d7ad 100644
> --- a/libavutil/channel_layout.h
> +++ b/libavutil/channel_layout.h
> @@ -358,8 +358,9 @@ typedef struct AVChannelLayout {
>       void *opaque;
>   } AVChannelLayout;
>   
> +/* Don't use designated initializers since C++ doesn't support it until C++20. */
>   #define AV_CHANNEL_LAYOUT_MASK(nb, m) \
> -    { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = (nb), .u = { .mask = (m) }}
> +    { /* .order */ AV_CHANNEL_ORDER_NATIVE, /* .nb_channels */  (nb), /* .u.mask */ { m }, /* .opaque */ NULL }
>   
>   /**
>    * @name Common pre-defined channel layouts
> @@ -397,7 +398,7 @@ typedef struct AVChannelLayout {
>   #define AV_CHANNEL_LAYOUT_STEREO_DOWNMIX    AV_CHANNEL_LAYOUT_MASK(2,  AV_CH_LAYOUT_STEREO_DOWNMIX)
>   #define AV_CHANNEL_LAYOUT_22POINT2          AV_CHANNEL_LAYOUT_MASK(24, AV_CH_LAYOUT_22POINT2)
>   #define AV_CHANNEL_LAYOUT_AMBISONIC_FIRST_ORDER \
> -    { .order = AV_CHANNEL_ORDER_AMBISONIC, .nb_channels = 4, .u = { .mask = 0 }}
> +    { /* .order */ AV_CHANNEL_ORDER_AMBISONIC, /* .nb_channels */ 4, /* .u.mask */ { 0 }, NULL }
>   /** @} */
>   
>   struct AVBPrint;
> diff --git a/libavutil/version.h b/libavutil/version.h
> index 5a4d4d3d73..bc43baca9f 100644
> --- a/libavutil/version.h
> +++ b/libavutil/version.h
> @@ -79,8 +79,8 @@
>    */
>   
>   #define LIBAVUTIL_VERSION_MAJOR  58
> -#define LIBAVUTIL_VERSION_MINOR  16
> -#define LIBAVUTIL_VERSION_MICRO 101
> +#define LIBAVUTIL_VERSION_MINOR  17
> +#define LIBAVUTIL_VERSION_MICRO 100
>   
>   #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
>                                                  LIBAVUTIL_VERSION_MINOR, \

Will apply with some cosmetic changes.