[Buildroot] [PATCH v1 0/3] qt5: fix build issue with mesa w/out xcb

[Peter Seiderer]

Hello Gaël,

On Thu, 22 Feb 2018 11:47:38 -0500, Gaël PORTAY <gael.portay at savoirfairelinux.com> wrote:

> All,
> 
> On Sun, Feb 11, 2018 at 11:25:21PM -0500, Gaël PORTAY wrote:
> > Hi all,
> > 
> > Julien Corjon and I have noticed a build issue with qtmultimedia,
> > qtwayland and qtwebkit modules when using mesa3d (as EGL backend)
> > without using XCB. When BR2_PACKAGE_LIBXCB is set the issue is gone.
> > Julien has opened an issue in Qt tracker[1].
> > 
> > The mesa's EGL/eglplatform.h header includes X11 headers unless the
> > macro MESA_EGL_NO_X11_HEADERS is defined[2].
> > 
> > 	/home/gportay/src/buildroot/output-qt5.10/host/x86_64-buildroot-linux-gnu/sysroot/usr/include/EGL/eglplatform.h:118:22: fatal error: X11/Xlib.h: No such file or directory
> > 	 #include <X11/Xlib.h>
> > 	                      ^
> > 	compilation terminated.
> > 
> > The workaround tells qmake to pass the cflag MESA_EGL_NO_X11_HEADERS to
> > make that prevents from including the missing X headers.
> > 
> > This workaround is performed in the situation when mesa3d is in use as
> > OpenGL EGL backend and when XCB library is *not* compiled.
> > 
> > [1]: https://bugreports.qt.io/browse/QTBUG-66233
> > [2]: https://github.com/mesa3d/mesa/blob/79ee1b2ff0b85f4eeb4165d23a7943c28d3a3d93/include/EGL/eglplatform.h#L109-L125
> >   
> 
> As discussed with Thomas on the #buildroot channel:
> 
> 	2018-02-16 09:01:14	kos_tom	gportay: I think the OpenGL implementation should provide those flags in its .pc file, and qt should pick them up from there
> 
> Hopefully, the MESA_EGL_NO_X11_HEADERS cflags is present the egl.pc file
> from mesa3d:
> 
> 	$ output/host/bin/pkg-config --cflags-only-other egl
> 	 -DMESA_EGL_NO_X11_HEADERS
> 
> I will work on a proper solution that will be integrated in every Qt
> projects that are impacted by this issue.
> 
> I need time/help to hundersand how qmake works in order to append the
> egl cflags given by pkg-config in qmake.
> 

Maybe take a look at the openembedded patch [1] (and upstream bug report[2]
and patch [3]) 'egl.prf: Fix build error when egl headers need platform
definition', stating:

  Gain the value through pkg-config and pass it through QMAKE_CFLAGS_EGL.

Regards,
Peter

[1] https://patchwork.openembedded.org/patch/141287/
[2] https://bugreports.qt.io/browse/QTBUG-61712
[3] https://codereview.qt-project.org/#/c/198906/

> I almost sure that I will miss the release. So, would you agree to
> accept this patch serie as a temporary workaround since it fixes a real
> build issue?
> 
> > Regards,
> > Gaël PORTAY (3):
> >   qt5webkit: fix build issue with mesa3d w/out xcb
> >   qt5multimedia: fix build issue with mesa3d w/out xcb
> >   qt5wayland: fix build issue with mesa3d w/out xcb
> > 
> >  package/qt5/qt5multimedia/qt5multimedia.mk | 11 ++++++++++-
> >  package/qt5/qt5wayland/qt5wayland.mk       |  9 +++++++++
> >  package/qt5/qt5webkit/qt5webkit.mk         | 11 ++++++++++-
> >  3 files changed, 29 insertions(+), 2 deletions(-)
> > 
> > -- 
> > 2.15.1
> >  
> 
> Regards,
> Gael
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