How to include OpenCV library into a project on Raspberry Pi

I installed OpenCV on Raspberry Pi4

sudo apt-get install libopencv-dev

Now I open a project in Qt and in main.cpp include

 #include "opencv2/opencv.hpp"
 //or - the same result
 //#include <opencv2/opencv.hpp>

Qt sees the directory and files in it. But when I compile I get a lot of errors in the opencv library files. Why? May be I should include it in the *.pro file - LIB+= ????? - what should I include?

The errors I get

-1: error: main.o: in function cv::String::~String()': -1: error: main.o: in function cv::String::operator=(cv::String const&)' :/usr/include/opencv2/core/cvstd.hpp:672: error: undefined reference to `cv::String::deallocate()' -1: error: collect2: error: ld returned 1 exit status