Can't build after opencv upgrade

[eeeps]

OS X / 10.14.2

$ make
g++ -std=c++11 -O2 -fstrict-aliasing -ffast-math `pkg-config --cflags opencv` ssimulacra.cpp `pkg-config --libs-only-L opencv` -lopencv_core -lopencv_highgui -lopencv_imgcodecs -lopencv_imgproc -o ssimulacra
Package opencv was not found in the pkg-config search path.
Perhaps you should add the directory containing `opencv.pc'
to the PKG_CONFIG_PATH environment variable
No package 'opencv' found
Package opencv was not found in the pkg-config search path.
Perhaps you should add the directory containing `opencv.pc'
to the PKG_CONFIG_PATH environment variable
No package 'opencv' found
ssimulacra.cpp:81:10: fatal error: 'cv.hpp' file not found
#include <cv.hpp>
         ^~~~~~~~
1 error generated.
make: *** [ssimulacra] Error 1

I’m guessing this is related to the fact that Homebrew recently upgraded my OpenCV to version 4.0.1. I took a stab at fixing it by finding something that looked like opencv.pc and symlinking it to that path:

$ ln -s /usr/local/Cellar/opencv/4.0.1/lib/pkgconfig/opencv4.pc /usr/local/lib/pkgconfig/opencv.pc

That got rid of the first error, but did not fix the second (fatal error: 'cv.hpp' file not found).

Any advice? Should I try to install an earlier version of OpenCV?

[malchata]

I'm also running into this now on macOS 10.15.1, @eeeps. Received same error messages after removing OpenCV 4 and doing brew install opencv@3. brew gave this advice:

For compilers to find opencv@3 you may need to set:
  export LDFLAGS="-L/usr/local/opt/opencv@3/lib"
  export CPPFLAGS="-I/usr/local/opt/opencv@3/include"

For pkg-config to find opencv@3 you may need to set:
  export PKG_CONFIG_PATH="/usr/local/opt/opencv@3/lib/pkgconfig"

Setting these vars worked and ssimulacra built fine.

[tpiros]

See #6 :)