[libcamera-devel] [PATCH] libcamera: pipeline: fix c++20 compile warning

[Laurent Pinchart]

Hello,

On Tue, Nov 14, 2023 at 04:05:16PM +0000, Barnabás Pőcze wrote:
> 2023. november 14., kedd 14:42 keltezéssel, Laurent Pinchart via libcamera-devel írta:
> > On Tue, Nov 14, 2023 at 12:53:04PM +0200, Laurent Pinchart via libcamera-devel wrote:
> > > Hi Brett,
> > > 
> > > Thank you for your first libcamera patch :-)
> > > 
> > > On Mon, Nov 13, 2023 at 09:52:44AM -0700, Brett Brotherton via libcamera-devel wrote:
> > > 
> > > > fix -Wdeprecated-this-capture error when building with c++20 by
> > > > explicity naming this in the capture
> > > 
> > > Nitpicking, s/fix/Fix/ and s/capture$/capture./
> > > 
> > > No need to resend the patch for this, I'll update the commit message
> > > before pushing.
> > > 
> > > Is this the only occurrence of implicit *this capture ? I'm happy we're
> > > not doing that bad :-)
> > > 
> > > > Signed-off-by: Brett Brotherton bbrotherton at google.com
> > > 
> > > Reviewed-by: Laurent Pinchart laurent.pinchart at ideasonboard.com
> > > 
> > > I will run this through build testing and push the patch if no issues
> > > are found.
> > 
> > Unfortunately problems have been found :-(
> > 
> > ../../src/libcamera/pipeline_handler.cpp:652:40: error: explicit capture of 'this' with a capture default of '=' is a C++20 extension [-Werror,-Wc++20-extensions]
> > media->disconnected.connect(this, =, this { mediaDeviceDisconnected(media); });
> > 
> > ^
> 
> I imagine explicitly capturing everything needed should fix that.
> 
> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> index 9c74c6cf..29e0c98a 100644
> --- a/src/libcamera/pipeline_handler.cpp
> +++ b/src/libcamera/pipeline_handler.cpp
> @@ -649,7 +649,7 @@ void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
>   */
>  void PipelineHandler::hotplugMediaDevice(MediaDevice *media)
>  {
> -       media->disconnected.connect(this, [=]() { mediaDeviceDisconnected(media); });
> +       media->disconnected.connect(this, [this, media] { mediaDeviceDisconnected(media); });
>  }
>  
>  /**

This seems fine. Brett, could you please test this (both with C++20 and
C++17) and send a new version of the patch ?

> > > > ---
> > > > src/libcamera/pipeline_handler.cpp | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> > > > index 9c74c6cf..2220cb92 100644
> > > > --- a/src/libcamera/pipeline_handler.cpp
> > > > +++ b/src/libcamera/pipeline_handler.cpp
> > > > @@ -649,7 +649,7 @@ void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
> > > > */
> > > > void PipelineHandler::hotplugMediaDevice(MediaDevice *media)
> > > > {
> > > > - media->disconnected.connect(this, = { mediaDeviceDisconnected(media); });
> > > > + media->disconnected.connect(this, =, this { mediaDeviceDisconnected(media); });
> > > > }
> > [...]

-- 
Regards,

Laurent Pinchart