[libcamera-devel] [PATCH] apps: cam: Fix compilation error with clang when libtiff-4 is not found

[Laurent Pinchart]

On Mon, Oct 24, 2022 at 12:43:19PM +0100, Kieran Bingham wrote:
> Quoting Laurent Pinchart via libcamera-devel (2022-10-24 11:46:38)
> > When libtiff-4 is not found, the private camera_ member of the FileSink
> > class is set but never used. This causes a compilation error with clang:
> > 
> > In file included from ../../src/apps/cam/file_sink.cpp:19:
> > ../../src/apps/cam/file_sink.h:39:27: error: private field 'camera_' is not used [-Werror,-Wunused-private-field]
> >         const libcamera::Camera *camera_;
> > 
> > Fix by making the camera_ member field conditional on HAVE_TIFF.
> 
> Ugh, this feels like an ugly fix. I hate it when compiler warnings
> (which I want to keep enabled) work against us like this.

I tried

	[[maybe_unused]] const libcamera::Camera *camera_;

it made clang happy, but gcc choke on it, telling the attribute was
ignored. I Gave up :-)

> Any other proposal is probably just a different ugly workaround on an
> unused arg so lets fix the build and ...
> 
> Acked-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> 
> > 
> > Fixes: 6404b163bcbb ("cam: file_sink: Add support for DNG output")
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> >  src/apps/cam/file_sink.cpp | 8 ++++++--
> >  src/apps/cam/file_sink.h   | 2 ++
> >  2 files changed, 8 insertions(+), 2 deletions(-)
> > 
> > diff --git a/src/apps/cam/file_sink.cpp b/src/apps/cam/file_sink.cpp
> > index 9d60c04e1cf4..4dfacc103c54 100644
> > --- a/src/apps/cam/file_sink.cpp
> > +++ b/src/apps/cam/file_sink.cpp
> > @@ -21,10 +21,14 @@
> >  
> >  using namespace libcamera;
> >  
> > -FileSink::FileSink(const libcamera::Camera *camera,
> > +FileSink::FileSink([[maybe_unused]] const libcamera::Camera *camera,
> >                    const std::map<const libcamera::Stream *, std::string> &streamNames,
> >                    const std::string &pattern)
> > -       : camera_(camera), streamNames_(streamNames), pattern_(pattern)
> > +       :
> > +#ifdef HAVE_TIFF
> > +         camera_(camera),
> > +#endif
> > +         streamNames_(streamNames), pattern_(pattern)
> >  {
> >  }
> >  
> > diff --git a/src/apps/cam/file_sink.h b/src/apps/cam/file_sink.h
> > index 9ce8b619f69d..300edf8dc902 100644
> > --- a/src/apps/cam/file_sink.h
> > +++ b/src/apps/cam/file_sink.h
> > @@ -36,7 +36,9 @@ private:
> >                          libcamera::FrameBuffer *buffer,
> >                          const libcamera::ControlList &metadata);
> >  
> > +#ifdef HAVE_TIFF
> >         const libcamera::Camera *camera_;
> > +#endif
> >         std::map<const libcamera::Stream *, std::string> streamNames_;
> >         std::string pattern_;
> >         std::map<libcamera::FrameBuffer *, std::unique_ptr<Image>> mappedBuffers_;
> > 
> > base-commit: 24f8ef763a60f410963fd8897a16ae077aaeff0d

-- 
Regards,

Laurent Pinchart