[FFmpeg-devel] bprint.h can't be included in C++ code

[Nicolas George]

Le primidi 1er frimaire, an CCXXIII, Vadim Kalinsky a écrit :
> bprint.h can't be included in C++ code
> C++ does not support anonymous struct.

Thanks for the patch.

Basically, bprint.h is not meant to be included in c++ code.

> From a45cc83a807e7eabf158ddff52751171e80874f8 Mon Sep 17 00:00:00 2001
> From: Vadim Kalinsky <vkalinsky at Q.local>
> Date: Fri, 21 Nov 2014 13:39:07 -0500
> Subject: [PATCH] C++ compatible AVBPrint definition.
> 
> ---
>  libavutil/bprint.h | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/libavutil/bprint.h b/libavutil/bprint.h
> index d1682fc..10e96d7 100644
> --- a/libavutil/bprint.h
> +++ b/libavutil/bprint.h
> @@ -30,9 +30,12 @@
>   * Define a structure with extra padding to a fixed size
>   * This helps ensuring binary compatibility with future versions.
>   */
> -#define FF_PAD_STRUCTURE(size, ...) \
> -    __VA_ARGS__ \
> -    char reserved_padding[size - sizeof(struct { __VA_ARGS__ })];

> +#define FF_PAD_STRUCTURE(name,size, ...) \
> +typedef struct __pad_structure_helper_##name { __VA_ARGS__ } __pad_structure_helper_##name; \
> +typedef struct name { \
> +__VA_ARGS__ \
> +char reserved_padding[size - sizeof(__pad_structure_helper_##name)]; \
> +} name;

Apart from the fact that it makes the macro hackery vastly less readable
(maybe some indentation would help), identifiers starting with a double
underscode are reserved for the implementation, and therefore can not be
used.

>  
>  /**
>   * Buffer to print data progressively
> @@ -74,15 +77,14 @@
>   * internal buffer is large enough to hold a reasonable paragraph of text,
>   * such as the current paragraph.
>   */
> -typedef struct AVBPrint {
> -    FF_PAD_STRUCTURE(1024,
> +
> +FF_PAD_STRUCTURE(AVBPrint, 1024,
>      char *str;         /**< string so far */
>      unsigned len;      /**< length so far */
>      unsigned size;     /**< allocated memory */
>      unsigned size_max; /**< maximum allocated memory */
>      char reserved_internal_buffer[1];
> -    )
> -} AVBPrint;
> +)
>  
>  /**
>   * Convenience macros for special values for av_bprint_init() size_max

Regards,

-- 
  Nicolas George
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