[FFmpeg-devel] libavutil/thread.h: Fixed g++ build error when ASSERT_LEVEL is greater than 1

[Clément Bœsch]

On Sun, Apr 16, 2017 at 05:20:02PM -0700, Aaron Levinson wrote:
> From 9e6a9e2b8d58f17c661a3f455e03c95587ec7b18 Mon Sep 17 00:00:00 2001
> From: Aaron Levinson <alevinsn at aracnet.com>
> Date: Sun, 16 Apr 2017 17:13:31 -0700
> Subject: [PATCH] libavutil/thread.h:  Fixed g++ build error when
>  ASSERT_LEVEL is greater than 1
> 
> Purpose: libavutil/thread.h: Fixed g++ build error when ASSERT_LEVEL
> is greater than 1.  This is only relevant when thread.h is included by
> C++ files.  In this case, the relevant code is only defined if
> HAVE_PTHREADS is defined as 1.  Use configure --assert-level=2 to do
> so.
> 
> Note: Issue discovered as a result of Coverity build failure.  Cause
> of build failure pinpointed by Hendrik Leppkes.
> 
> Comments:
> 
> -- libavutil/thread.h: Altered ASSERT_PTHREAD_NORET definition such
>    that it uses av_make_error_string instead of av_err2str().
>    av_err2str() uses a "parenthesized type followed by an initializer
>    list", which is apparently not valid C++.  This issue started
>    occurring because thread.h is now included by the DeckLink C++
>    files.  The alteration does the equivalent of what av_err2str()
>    does, but instead declares the character buffer as a local
>    variable.
> ---
>  libavutil/thread.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/libavutil/thread.h b/libavutil/thread.h
> index 6e57447..f108e20 100644
> --- a/libavutil/thread.h
> +++ b/libavutil/thread.h
> @@ -36,8 +36,11 @@
>  #define ASSERT_PTHREAD_NORET(func, ...) do {                            \
>      int ret = func(__VA_ARGS__);                                        \
>      if (ret) {                                                          \
> +        char errbuf[AV_ERROR_MAX_STRING_SIZE] = "";                     \
>          av_log(NULL, AV_LOG_FATAL, AV_STRINGIFY(func)                   \
> -               " failed with error: %s\n", av_err2str(AVERROR(ret)));   \
> +               " failed with error: %s\n",                              \
> +               av_make_error_string(errbuf, AV_ERROR_MAX_STRING_SIZE,   \
> +                                    AVERROR(ret)));                     \
>          abort();                                                        \
>      }                                                                   \
>  } while (0)

I don't like limiting ourselves in the common C code of the project
because C++ is a bad and limited language. Can't you solve this by bumping
the minimal requirement of C++ version?

-- 
Clément B.
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