[libcamera-devel] [PATCH] gst: Fix GLib detection and warning disabling

[Nicolas Dufresne]

Le samedi 07 mars 2020 à 02:33 +0200, Laurent Pinchart a écrit :
> Commit 17cccc68a88f ("Add GStreamer plugin and element skeleton") has
> gained a last minute fix for a clang compilation error with GLib prior
> to v2.63.0. The fix wasn't properly tested, and not only did it try to
> silence the affected compiler warning for C files only, it also failed
> to check the GLib dependency correctly. This resulted in compilation of
> the GStreamer element to always be disabled.
> 
> Fix this by changing the GLib package name from 'glib' to 'glib-2.0',
> and silence the compiler warning for C++ files.
> 
> Fixes: 17cccc68a88f ("Add GStreamer plugin and element skeleton")
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  src/gstreamer/meson.build | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/src/gstreamer/meson.build b/src/gstreamer/meson.build
> index 1965b5041132..1b9dedd2528e 100644
> --- a/src/gstreamer/meson.build
> +++ b/src/gstreamer/meson.build
> @@ -12,8 +12,9 @@ libcamera_gst_c_args = [
>      '-DVERSION="@0@"'.format(libcamera_git_version),
>      '-DPACKAGE="@0@"'.format(meson.project_name()),
>  ]
> +libcamera_gst_cpp_args = []
>  
> -glib_dep = dependency('glib', required : get_option('gstreamer'))
> +glib_dep = dependency('glib-2.0', required : get_option('gstreamer'))
>  
>  gst_dep_version = '>=1.14.0'
>  gstvideo_dep = dependency('gstreamer-video-1.0', version : gst_dep_version,
> @@ -27,12 +28,13 @@ if glib_dep.found() and gstvideo_dep.found() and gstallocator_dep.found()
>      # complain about the ones we are not using. Silence the -Wunused-function
>      # warning in that case.
>      if cc.get_id() == 'clang' and glib_dep.version().version_compare('<2.63.0')
> -        libcamera_gst_c_args += [ '-Wno-unused-function' ]
> +        libcamera_gst_cpp_args += [ '-Wno-unused-function' ]

We have gstlibcamera.c that includes gstlibcameraprovider.h and
gstlibcamerasrc.h, so shouldn't this be setting both C and CPP args ? 

If I may, maybe we could simply move gstlibcamera.c to gstlibcamera.cpp
and drop the C args. The generated code by GST_DEFINE_PLUGIN is inside
a scope of:

  extern "C" {
    
  }

>      endif
>  
>      libcamera_gst = shared_library('gstlibcamera',
>          libcamera_gst_sources,
>          c_args : libcamera_gst_c_args,
> +        cpp_args : libcamera_gst_cpp_args,
>          dependencies : [libcamera_dep, gstvideo_dep, gstallocator_dep],
>          install: true,
>          install_dir : '@0@/gstreamer-1.0'.format(get_option('libdir')),
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