build error on opencv (Ubuntu and Debian)

Compiling or Editing the Panda Source
1

I have built latest source on both Debian 7.7 (wheezy) and Ubuntu 14.04.1 (trusty) using this command

makepanda/makepanda.py --verbose --everything --threads 4 --optimize 3 --installer --no-ffmpeg --no-fftw

and I’ve got this error:

...
In file included from /usr/include/opencv2/flann/flann_base.hpp:42:0,
                 from /usr/include/opencv2/flann/flann.hpp:50,
                 from /usr/include/opencv/cv.h:69,
                 from built/tmp/libp3vision_igate.cxx:18:
/usr/include/opencv2/flann/saving.h: In function ‘cvflann::IndexHeader cvflann::load_header(FILE*)’:
/usr/include/opencv2/flann/saving.h:113:63: error: exception handling disabled, use -fexceptions to enable
         throw FLANNException("Invalid index file, cannot read");
                                                               ^
In file included from /usr/include/opencv2/flann/flann_base.hpp:42:0,
                 from /usr/include/opencv2/flann/flann.hpp:50,
                 from /usr/include/opencv/cv.h:69,
                 from panda/src/vision/openCVTexture.h:33,
                 from panda/src/vision/config_vision.cxx:16,
                 from panda/src/vision/p3vision_composite1.cxx:2:
/usr/include/opencv2/flann/saving.h: In function ‘cvflann::IndexHeader cvflann::load_header(FILE*)’:
/usr/include/opencv2/flann/saving.h:113:63: error: exception handling disabled, use -fexceptions to enable
         throw FLANNException("Invalid index file, cannot read");
                                                               ^
Process exited with exit status 1 and signal code 0
The following command returned a non-zero value: g++ -ftemplate-depth-50 -fPIC -c -o built/tmp/p3vision_composite1.o -Ibuilt/tmp -Ibuilt/include -I/usr/include/python2.7 -I/usr/include/eigen3 -I/usr/include/opencv -Ipanda/src/vision -pthread -fno-exceptions -msse2 -O2 -DBUILDING_VISION panda/src/vision/p3vision_composite1.cxx
...

Which could be the issue?

2

After little examination, the issue seems due to FLANN ( Fast Approximate Nearest Neighbor Search Library ) module of opencv, which throw exceptions (as in /usr/include/opencv2/flann/saving.h).
I tried to uninstall libopencv-flann-dev debian package, but in this case makepanda exluded opencv support entirely.
So, for opencv support, -fno-exceptions should not be used.
I tried to set CXXFLAGS="-fexceptions" environment variable and build was successful.
Now, my question is if it is possible to set “-fexceptions” selectively only for modules which need opencv?

3

Thanks for the detective work! Yes, there’s an “EXCEPTIONS” option that should be added to the OPTS list of the relevant section in makepanda.py.

4

I just pushed something that should fix it. Thanks again.