[libcamera-devel] [PATCH] file_sink.cpp: Avoid dangling-reference

[Eric Curtin]

On Tue, 24 Jan 2023 at 09:22, Khem Raj via libcamera-devel
<libcamera-devel at lists.libcamera.org> wrote:
>
> Fixes following errors with gcc-13
>
> ../git/src/cam/file_sink.cpp:92:45: error: possibly dangling reference to a temporary [-Werror=dangling-reference]
>    92 |                 const FrameMetadata::Plane &meta = buffer->metadata().planes()[i];
>       |                                             ^~~~
> ../git/src/cam/file_sink.cpp:92:81: note: the temporary was destroyed at the end of the full expression '(& buffer->libcamera::FrameBuffer::metadata())->libcamera::FrameMetadata::planes().libcamera::Span<const libcamera::FrameMetadata::Plane>::operator[](i)'
>    92 |                 const FrameMetadata::Plane &meta = buffer->metadata().planes()[i];
>       |                                                                                 ^
> cc1plus: all warnings being treated as errors
>
> Signed-off-by: Khem Raj <raj.khem at gmail.com>

I understand this is a compiler bug, but could we merge this anyway?
Having the same issue in Fedora 38 and this code is just as good as
the code that reproduces the compiler bug.

Reviewed-by: Eric Curtin <ecurtin at redhat.com>

Is mise le meas/Regards,

Eric Curtin

> ---
>  src/cam/file_sink.cpp | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/src/cam/file_sink.cpp b/src/cam/file_sink.cpp
> index 45213d4a..897c4b37 100644
> --- a/src/cam/file_sink.cpp
> +++ b/src/cam/file_sink.cpp
> @@ -89,13 +89,13 @@ void FileSink::writeBuffer(const Stream *stream, FrameBuffer *buffer)
>         Image *image = mappedBuffers_[buffer].get();
>
>         for (unsigned int i = 0; i < buffer->planes().size(); ++i) {
> -               const FrameMetadata::Plane &meta = buffer->metadata().planes()[i];
> +               unsigned int bytesused = buffer->metadata().planes()[i].bytesused;
>
>                 Span<uint8_t> data = image->data(i);
> -               unsigned int length = std::min<unsigned int>(meta.bytesused, data.size());
> +               unsigned int length = std::min<unsigned int>(bytesused, data.size());
>
> -               if (meta.bytesused > data.size())
> -                       std::cerr << "payload size " << meta.bytesused
> +               if (bytesused > data.size())
> +                       std::cerr << "payload size " << bytesused
>                                   << " larger than plane size " << data.size()
>                                   << std::endl;
>
> --
> 2.39.1
>