[libcamera-devel] [PATCH] libcamera: camera: Fix unused variable compiler warning

[Laurent Pinchart]

On Wed, Dec 20, 2023 at 12:42:12PM +0000, Kieran Bingham wrote:
> Quoting Laurent Pinchart via libcamera-devel (2023-12-18 14:13:13)
> > When compiling with gcc 8.4.0, the compiler throws an unused variable
> > warning:
> > 
> > ../src/libcamera/camera.cpp: In member function ‘libcamera::CameraConfiguration::Status libcamera::CameraConfiguration::validateColorSpaces(libcamera::CameraConfiguration::ColorSpaceFlags)’:
> > ../src/libcamera/camera.cpp:497:19: error: unused variable ‘i’ [-Werror=unused-variable]
> >   for (auto [i, cfg] : utils::enumerate(config_)) {
> >                    ^
> > 
> > While the code compiles fine with 8.3.0 and 8.5.0, gcc is right here,
> 
> Curious to only hit on one intermediate version.

I think the issue was actually caused by a misconfiguration of the build
environment of the reporter of the issue. They used gcc 8.4.0 but g++
7.x. I don't want to explain this mess in the commit message though, and
as I can't easily test if g++ 8.4.0 exhibits the issue, I've left the
message as is.

> > the 'i' variable is unused. It turns out that the code can be
> > simplified, as the commit that removed usage of the variable kept the
> > now unneeded utils::enumerate() call.
> > 
> > Simplify the code and fix the warning in one go.
> 
> Indeed.
> 
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> 
> > Fixes: 13986d6ce3ab ("libcamera: camera: Fix validateColorSpaces to choose "main" colour space")
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> >  src/libcamera/camera.cpp | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
> > index 0ad1a4b50447..a71dc933b911 100644
> > --- a/src/libcamera/camera.cpp
> > +++ b/src/libcamera/camera.cpp
> > @@ -494,7 +494,7 @@ CameraConfiguration::Status CameraConfiguration::validateColorSpaces(ColorSpaceF
> >         std::optional<ColorSpace> colorSpace;
> >         Size size;
> >  
> > -       for (auto [i, cfg] : utils::enumerate(config_)) {
> > +       for (StreamConfiguration &cfg : config_) {
> >                 if (!cfg.colorSpace)
> >                         continue;
> >  
> > 
> > base-commit: 41d6e6e5c166c267e7a15a7b0c1d930bddcbc6b8

-- 
Regards,

Laurent Pinchart