[libcamera-devel] [PATCH v2] cam: file_sink: Fixes following errors with gcc-13

[Laurent Pinchart]

Hi Eric,

(CC'ing Barnabás)

Thank you for the patch.

On Tue, Feb 14, 2023 at 12:14:49PM +0000, Eric Curtin via libcamera-devel wrote:
> ../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

This seems to be a false positive from an unreleased gcc version. Could
you report the issue to upstream gcc ? I'd like to get it fixed if it's
indeed a false positive, or at least get confirmation from them that
they won't fix it.

> Co-developed-by: Khem Raj <raj.khem at gmail.com>
> Signed-off-by: Eric Curtin <ecurtin at redhat.com>
> ---
> Changes in v2:
> 
> - Added const
> - Made patch mergeable by accounting for new directory structure
> ---
>  src/apps/cam/file_sink.cpp | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/src/apps/cam/file_sink.cpp b/src/apps/cam/file_sink.cpp
> index b32aad24..d41569c9 100644
> --- a/src/apps/cam/file_sink.cpp
> +++ b/src/apps/cam/file_sink.cpp
> @@ -114,13 +114,12 @@ void FileSink::writeBuffer(const Stream *stream, FrameBuffer *buffer,
>  	}
>  
>  	for (unsigned int i = 0; i < buffer->planes().size(); ++i) {
> -		const FrameMetadata::Plane &meta = buffer->metadata().planes()[i];
> -
> +		const 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());
> +		const 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;
>  

-- 
Regards,

Laurent Pinchart