编译 opencv 4 基本程序时出现链接错误？答案

【问题标题】：I am getting linking error while compilong opencv4 basic program?编译 opencv 4 基本程序时出现链接错误？
【发布时间】：2019-05-15 13:26:13
【问题描述】：

我使用 Pacman 命令安装了 OpenCV。但是我收到了数百行链接错误。我用命令编译了我的程序

gcc example.cpp -o example `pkg-config --cflags --libs opencv4`

还有一小部分链接错误如下。

usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkRenderingFreeType_AutoInit_Destruct()'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkInteractorStyle::StartTwoPointer()'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkInteractorStyle::EndZoom()'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkSmartPointerBase::operator=(vtkObjectBase*)'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkOStrStreamWrapper::freeze(int)'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkCamera::SetUserTransform(vtkHomogeneousTransform*)'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkCommand::UnRegister()'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkRenderer::New()'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkInteractorStyle::StartDolly()'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkRenderer::SetActiveCamera(vtkCamera*)'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkInteractorObserver::ReleaseFocus()'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkInteractorObserver::ComputeDisplayToWorld(double, double, double, double*)'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkAlgorithm::Update(vtkInformation*)'
/usr/bin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/8.3.0/../../../../lib/libopencv_viz.so: undefined reference to `vtkMatrix4x4::New()'

【问题讨论】：

我使用了pkg-config --cflags --libs opencv4，因为 /usr/pkgconfig/ 上没有 opencv.pc 文件。 opencv4.pc 文件包含与 opencv.pc 相同的内容，所以这个文件没有问题。

标签： c++ dependencies linker-errors pacman-package-manager opencv4

【解决方案1】：

opencv 库本身就在那里，但libopencv_viz.so 需要 vtk 库中的一些符号，这些符号在 opencv 的 PKGBUILD 中列为 optional dependency。

你应该自己安装它（例如pacman -S [--asdeps] vtk），或者如果你认为依赖项应该是非可选的，请向PKGBUILD维护人员投诉。

【讨论】：