[Development] ERROR: Feature 'webengine-system-libwebp' was enabled, but the pre-condition 'libs.webengine-webp' failed.

[YuGiOhJCJ Mailing-List]

Thanks!

I did:
$ pkg-config --libs libwebp libwebpmux libwebpdemux
Package libwebpmux was not found in the pkg-config search path.
Perhaps you should add the directory containing `libwebpmux.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libwebpmux' found

Then I saw that libwebpmux was not found.
The reason is that my libwebp library was built without the "--enable-libwebpmux" option.

So, I rebuilt my libwebp library:
$ ./configure \
	--disable-static \
	--enable-shared \
[...]
	--enable-libwebpmux \
[...]

Now, libwebpmux is found:
$ pkg-config --libs libwebp libwebpmux libwebpdemux
-lwebpmux -lwebpdemux -lwebp

And the Qt build system is happy:
---
$ ./configure -v \
[...]
	-system-assimp \
	-system-doubleconversion \
	-system-freetype \
	-system-harfbuzz \
	-system-libjpeg \
	-system-libpng \
	-system-pcre \
	-system-sqlite \
	-system-xcb \
	-system-webengine-icu \
	-system-webengine-ffmpeg \
	-system-webengine-opus \
	-system-webengine-webp \
	-system-zlib \
[...]
	-pulseaudio
[...]
Note: Also available for Linux: linux-clang linux-icc

Note: -headerdir is not a subdirectory of -prefix.
Note: -libdir is not a subdirectory of -prefix.
Note: -docdir is not a subdirectory of -prefix.

Note: -optimized-tools is not useful in -release mode.

Note: Dropped compiler flags '-pthread' when detecting library 'glib'.

Note: Dropped compiler flags '-pthread' when detecting library 'gtk3'.

Note: No wayland-egl support detected. Cross-toolkit compatibility disabled.

Note: Dropped compiler flags '-pthread' when detecting library 'gstreamer'.

Note: Dropped compiler flags '-pthread' when detecting library 'gstreamer_app'.

Note: Dropped compiler flags '-pthread' when detecting library 'webengine-protobuf'.

Qt is now configured for building. Just run 'make'.
Once everything is built, you must run 'make install'.
Qt will be installed into '/usr/lib64/qt5'.

Prior to reconfiguration, make sure you remove any leftovers from
the previous build.
---

Problem fixed!

On Mon, 12 Mar 2018 11:29:40 +0100
Michal Klocek <michal.klocek at qt.io> wrote:

> Hi
> 
> With 'system-webengine-webp' option you are trying to force qwebenigne
> to use system webp. WebEngine uses pkg-config for webp, there is no
> separate test, you can check it yourself with:
> 
> pkg-config --libs libwebp libwebpmux libwebpdemux
> 
> Br
> 
> Michal
> 
> On 03/12/2018 11:07 AM, YuGiOhJCJ Mailing-List via Development wrote:
> > Hello,
> > 
> > I am trying to build Qt 5.10.1 on Slackware64 14.2 with the "-system-webengine-webp" option and libwebp 0.6.1:
> > ---
> > $ ./configure -v \
> > [...]
> > 	-system-assimp \
> > 	-system-doubleconversion \
> > 	-system-freetype \
> > 	-system-harfbuzz \
> > 	-system-libjpeg \
> > 	-system-libpng \
> > 	-system-pcre \
> > 	-system-sqlite \
> > 	-system-xcb \
> > 	-system-webengine-icu \
> > 	-system-webengine-ffmpeg \
> > 	-system-webengine-opus \
> > 	-system-webengine-webp \
> > 	-system-zlib \
> > [...]
> > 	-pulseaudio
> > [...]
> > Note: Also available for Linux: linux-clang linux-icc
> > 
> > Note: -headerdir is not a subdirectory of -prefix.
> > Note: -libdir is not a subdirectory of -prefix.
> > Note: -docdir is not a subdirectory of -prefix.
> > 
> > Note: -optimized-tools is not useful in -release mode.
> > 
> > Note: Dropped compiler flags '-pthread' when detecting library 'glib'.
> > 
> > Note: Dropped compiler flags '-pthread' when detecting library 'gtk3'.
> > 
> > Note: No wayland-egl support detected. Cross-toolkit compatibility disabled.
> > 
> > Note: Dropped compiler flags '-pthread' when detecting library 'gstreamer'.
> > 
> > Note: Dropped compiler flags '-pthread' when detecting library 'gstreamer_app'.
> > 
> > Note: Dropped compiler flags '-pthread' when detecting library 'webengine-protobuf'.
> > 
> > ERROR: Feature 'webengine-system-libwebp' was enabled, but the pre-condition 'libs.webengine-webp' failed.
> > 
> > ERROR: Feature 'webengine-system-ffmpeg' was enabled, but the pre-condition 'libs.webengine-ffmpeg && features.webengine-system-opus && features.webengine-system-libwebp' failed.
> > ---
> > 
> > As you can see in the output above, the error is about the libwebp library that is not found (or at least that is not working correctly).
> > 
> > However, I found the test file that is checking the libwebp library and I tried it manually:
> > ---
> > $ cd qtimageformats/config.tests/libwebp
> > $ qmake libwebp.pro
> > $ make
> > g++ -c -pipe -O2 -Wall -W  -I/usr/lib64/qt/mkspecs/linux-g++ -I. -o libwebp.o libwebp.cpp
> > libwebp.cpp: In function ‘int main(int, char**)’:
> > libwebp.cpp:40:20: warning: unused variable ‘output_buffer’ [-Wunused-variable]
> >      WebPDecBuffer *output_buffer = &config.output;
> >                     ^~~~~~~~~~~~~
> > libwebp.cpp:41:28: warning: unused variable ‘bitstream’ [-Wunused-variable]
> >      WebPBitstreamFeatures *bitstream = &config.input;
> >                             ^~~~~~~~~
> > libwebp.cpp:42:17: warning: variable ‘picture’ set but not used [-Wunused-but-set-variable]
> >      WebPPicture picture;
> >                  ^~~~~~~
> > libwebp.cpp:44:16: warning: variable ‘config2’ set but not used [-Wunused-but-set-variable]
> >      WebPConfig config2;
> >                 ^~~~~~~
> > libwebp.cpp:47:18: warning: unused variable ‘demuxer’ [-Wunused-variable]
> >      WebPDemuxer *demuxer = WebPDemux(&data);
> >                   ^~~~~~~
> > libwebp.cpp:48:18: warning: variable ‘iter’ set but not used [-Wunused-but-set-variable]
> >      WebPIterator iter;
> >                   ^~~~
> > ---
> > 
> > So, the test file is working.
> > I am able to build it manually.
> > 
> > Why the Qt build system is complaining about this library installed on my system please?
> > 
> > Thank you.
> > Best regards.
> > _______________________________________________
> > Development mailing list
> > Development at qt-project.org
> > http://lists.qt-project.org/mailman/listinfo/development
> >