<h5 dir="auto">System information (version)</h5>
<ul dir="auto">
<li>OpenCV =&gt; 4.2 master</li>
<li>Operating System / Platform =&gt; macOS Catalina 10.15.5</li>
<li>Compiler =&gt; Cmake 3.18.1; GNU Make 3.81</li>
</ul>
<h5 dir="auto">Detailed description</h5>
<p dir="auto">trying to build OpenCV but getting many errors when run "make -j7". The errors are in train cascade apps folder files.</p>
<h5 dir="auto">Steps to reproduce</h5>
<p dir="auto">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.<br>
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.</p>
<p dir="auto">Few of the errors extract:</p>

<p dir="auto"><a href="https://github.com/opencv/opencv/files/5080128/build_error.txt">build_error.txt</a></p>
<p dir="auto">Hey,<br>
I built opencv 4.0.0 with</p>
<p dir="auto">cmake -D CMAKE_BUILD_TYPE=RELEASE <br>
-D BUILD_opencv_apps=ON <br>
-D OPENCV_EXTRA_MODULES_PATH=&lt;path_to...&gt;/modules ..</p>
<p dir="auto">However, in "build/app" there are no createsamples and traincascade. There are annotation, interractive-calibration, version and visualisation only.<br>
These folders are present in &lt;opencv_src&gt;/apps.<br>
OS - Ubuntu 16.06 LTS</p>
<p dir="auto">Versions 3.4.X worked fine.</p>
<p dir="auto">Is this changed recently?</p>