System information (version)

• OpenCV => at least 3.1 but also 4.1.1
• Operating System / Platform => Linux
• Compiler => >= gcc 7.1

Detailed description

When converting typed cv::Mat_<...> from one type to another with gcc >= 7.1 with c++17 enabled an endless recursion is generated leading to a stack overflow, thus the software is terminated with a segfault. In c++14 mode this issue does not occure.

I created a summary version of the Mat classes in godbolt where you can see the issue directly in assembly: https://gcc.godbolt.org/z/f8vFZj

Steps to reproduce

Compile this short example with c++ 17 enabled:

#include "opencv2/core.hpp"
int main()
{
  cv::Mat_<unsigned char> m1;
  cv::Mat_<signed char> m2{m1};
  return 0;
}

Or see the example on godbolt above.