OpenCV build failed using make -j7. errors in apps > traincascade various cpp files

[iruriksl]

System information (version)

• OpenCV => 4.2 master
• Operating System / Platform => macOS Catalina 10.15.5
• Compiler => Cmake 3.18.1; GNU Make 3.81

Detailed description

trying to build OpenCV but getting many errors when run "make -j7". The errors are in train cascade apps folder files.

Steps to reproduce

Downlaod master code. remove comments for create cascade and traincascade in Cmake file of apps directory. Configure and Generate using CMake Gui. Run command make -j7 and the error starts generating.
Tried rectifying them in "old_ml.hpp" for CvFileStorage by using cv::FileStorage and so on. But on correcting many different errors occur in many of the files in this folder.

Few of the errors extract:

build_error.txt

[alalek]

remove comments for create cascade and traincascade

They are commented for reason - not supported anymore.
Use OpenCV 3.4 instead.

duplicate of #13231

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Build / usage questions should go to Users OpenCV Q/A forum: http://answers.opencv.org

[dogbaha]

I got the same problem , and I fix it by using opecv-3.4.5. Write the method if you found a better way to get createcascade and createsamples under opencv-4+

os: centos 8
gcc : 8.3 c++11
cmake : 3.11