【发布时间】：2015-07-12 08:19:03
【问题描述】：
与question 类似，我在 OS X 10.10.3 上使用 OpenCV 和 CMake 时遇到了麻烦。
经过一番折腾，我终于设法在我的系统上构建了 OpenCV 3.0 beta；标头现在位于/usr/local/include 中，而库——它们应该——位于/usr/local/lib 中。我有使用 OpenCV 的小程序，我的 CMakeLists.txt 看起来像这样
set( CMAKE_CXX_FLAGS "-O3 -w" )
find_package( OpenCV REQUIRED )
if(OpenCV_FOUND)
message("Found OpenCV")
message("Includes: " ${OpenCV_INCLUDE_DIRS})
endif(OpenCV_FOUND)
add_executable( cannyDetector canny/canny.cpp )
target_link_libraries( cannyDetector ${OpenCV_LIBS} )
我还是习惯了
Undefined symbols for architecture x86_64:
"vtable for cv::_InputArray", referenced from:
_main in correctImage.o
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
"vtable for cv::_OutputArray", referenced from:
_main in correctImage.o
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
ld: symbol(s) not found for architecture x86_64
collect2: error: ld returned 1 exit status
make[2]: *** [correctImage] Error 1
make[1]: *** [CMakeFiles/correctImage.dir/all] Error 2
make: *** [all] Error 2
变量OpenCV_LIBS包含
opencv_xphoto;opencv_xobjdetect;opencv_ximgproc;opencv_xfeatures2d;opencv_tracking;opencv_text;opencv_surface_matching;opencv_saliency;opencv_rgbd;opencv_reg;opencv_optflow;opencv_line_descriptor;opencv_latentsvm;opencv_ccalib;opencv_bioinspired;opencv_bgsegm;opencv_adas;opencv_videostab;opencv_videoio;opencv_video;opencv_ts;opencv_superres;opencv_stitching;opencv_shape;opencv_photo;opencv_objdetect;opencv_ml;opencv_imgproc;opencv_imgcodecs;opencv_highgui;opencv_hal;opencv_flann;opencv_features2d;opencv_core;opencv_calib3d
另外，手动编译也可以：
gcc -o canny $(pkg-config --cflags opencv3) $(pkg-config --libs opencv3) -lstdc++ -w -O3 ../canny/canny.cpp
（我不知道为什么我必须指定-lstdc++，但没有它，链接会因另一个原因而失败）。
运行make VERBOSE=1 时，可执行以下命令：
/opt/local/bin/g++ -O3 -w -lstdc++ -Wl,-search_paths_first -Wl,-headerpad_max_install_names CMakeFiles/cannyDetector.dir/canny/canny.o -o cannyDetector /usr/local/lib/libopencv_xphoto.3.0.0.dylib /usr/local/lib/libopencv_ximgproc.3.0.0.dylib /usr/local/lib/libopencv_tracking.3.0.0.dylib /usr/local/lib/libopencv_text.3.0.0.dylib /usr/local/lib/libopencv_surface_matching.3.0.0.dylib /usr/local/lib/libopencv_saliency.3.0.0.dylib /usr/local/lib/libopencv_rgbd.3.0.0.dylib /usr/local/lib/libopencv_reg.3.0.0.dylib /usr/local/lib/libopencv_optflow.3.0.0.dylib /usr/local/lib/libopencv_line_descriptor.3.0.0.dylib /usr/local/lib/libopencv_latentsvm.3.0.0.dylib /usr/local/lib/libopencv_ccalib.3.0.0.dylib /usr/local/lib/libopencv_bioinspired.3.0.0.dylib /usr/local/lib/libopencv_bgsegm.3.0.0.dylib /usr/local/lib/libopencv_adas.3.0.0.dylib /usr/local/lib/libopencv_videostab.3.0.0.dylib /usr/local/lib/libopencv_ts.a /usr/local/lib/libopencv_superres.3.0.0.dylib /usr/local/lib/libopencv_stitching.3.0.0.dylib /usr/local/lib/libopencv_photo.3.0.0.dylib /usr/local/lib/libopencv_objdetect.3.0.0.dylib /usr/local/lib/libopencv_hal.a /usr/local/lib/libopencv_xobjdetect.3.0.0.dylib /usr/local/lib/libopencv_xfeatures2d.3.0.0.dylib /usr/local/lib/libopencv_shape.3.0.0.dylib /usr/local/lib/libopencv_video.3.0.0.dylib /usr/local/lib/libopencv_calib3d.3.0.0.dylib /usr/local/lib/libopencv_features2d.3.0.0.dylib /usr/local/lib/libopencv_ml.3.0.0.dylib /usr/local/lib/libopencv_highgui.3.0.0.dylib /usr/local/lib/libopencv_videoio.3.0.0.dylib /usr/local/lib/libopencv_imgcodecs.3.0.0.dylib /usr/local/lib/libopencv_imgproc.3.0.0.dylib /usr/local/lib/libopencv_flann.3.0.0.dylib /usr/local/lib/libopencv_core.3.0.0.dylib /usr/local/lib/libopencv_hal.a -framework AGL -framework OpenGL /usr/local/share/OpenCV/3rdparty/lib/libippicv.a
但是，如果我接受命令并将输入文件CMakeFiles/cannyDetector.dir/canny/canny.o 替换为输入源文件../canny/canny.cpp，它就可以工作！
所以库都在了，但是还是编译不出来，因为编译器无法链接目标文件，但是一步编译链接就可以了。
谁能建议这里发生了什么？
【问题讨论】：
-
使用 make VERBOSE=yes 获得详细输出 cmake 如何调用编译器
-
您可能已经使用
libstdc++构建了OpenCV 库，而CMake 可能正在尝试使用libc++。建议：尝试在 CMake 文件中添加set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libstdc++")。 -
@Kiran 你是对的，因为该标志是绝对需要的，但它的缺失不会导致错误，但 CMake 拒绝找到
usr/local/lib中的库这一事实。跨度> -
请添加
message("OpenCV_LIBS=${OpenCV_LIBS}")并发布输出。检查您是否真的设法构建highgui：有时 OpenCV 中的库禁用（例如，由于缺少一些第 3 方库）并不那么明显。此外，如果您运行make VERBOSE=1，您可以看到实际的链接器命令行。 -
在再次编译库后，我已更新问题以反映我遇到的错误的最新变化。 @Antonio 这绝对不是特定库的问题，这些都已构建并准备就绪。
标签： c++ opencv linker cmake makefile