在我自己的C+；上链接OpenCV.js模块时出错+；使用Emscripten初始化 我一直在C++代码中工作，从网络摄像头接收图像数据（灰度），并将检测到的角数（快速转角）返回到JavaScript。为了获得成功编译代码，我下载并编译OpenCV.JS，用ESPRONTEN创建每个库，编码我自己的C++类来获得图像数据，包括OpenCV.HPP和BooD。工作非常好

当我决定使用OpenCV FeatureDetector时，我的问题就开始了。我能够编译只包含头的代码，但是一旦我从这个模块插入指令，我就得到了一个链接错误。 触发链接错误的代码行是：

Ptr<FeatureDetector> detector = ORB::create();

链接错误：

[100%] Linking CXX executable MyCV.js
error: undefined symbol: gzclose
warning: Link with `-s LLD_REPORT_UNDEFINED` to get more information on undefined symbols
warning: To disable errors for undefined symbols use `-s ERROR_ON_UNDEFINED_SYMBOLS=0`
error: undefined symbol: gzeof
error: undefined symbol: gzgets
error: undefined symbol: gzopen
error: undefined symbol: gzputs
error: undefined symbol: gzrewind
Error: Aborting compilation due to previous errors
shared:ERROR: '/Users/dev/Documents/_Git/emsdk/node/12.9.1_64bit/bin/node /Users/dev/Documents/_Git/emsdk/upstream/emscripten/src/compiler.js /var/folders/94/qc6kgl3x6r30g7y04t_9w4w00000gn/T/tmpDzc2sz.txt' failed (1)
make[2]: *** [MyCV.js] Error 1
make[1]: *** [CMakeFiles/MyCV.dir/all] Error 2
make: *** [all] Error 2

在opencvjs编译库上运行nm命令时显示的消息：

dev# nm libopencv_features2d.a
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(agast.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(agast_score.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(akaze.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(bagofwords.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(blobdetector.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(brisk.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(draw.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(dynamic.cpp.o) Unexpected metadata version: 2 (Expected: 1)
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(evaluation.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(fast.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(fast_score.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(feature2d.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(gftt.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(kaze.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(AKAZEFeatures.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(KAZEFeatures.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(fed.cpp.o) Unexpected metadata version: 2 (Expected: 1)
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(nldiffusion_functions.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(keypoint.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(main.cpp.o) Unexpected metadata version: 2 (Expected: 1)
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(matchers.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(mser.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(orb.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(opencl_kernels_features2d.cpp.o) Unexpected metadata version: 2 (Expected: 1)

谢谢你们的帮助。

我成功了。 多亏了@ÖöTiib info，我意识到build_js.py有一个编译Zlib的标志

在我的CMakeLists.txt中没有对该库的引用。所以我补充说：

target_link_libraries(MyCV /Users/dev/Documents/_Git/opencv/build_wasm/3rdparty/lib/libzlib.a)

---

问题已解决；）

似乎libz没有链接。C++链接器错误是最简单的问题，所以当这些问题引起麻烦时，应该避免使用。谢谢@ TIIB给你的提示。在build_js.py中确实有一个编译zlib的标志，它被设置为ON。可能lib存储在另一个dir中，而这个dir不在我的CMakeLists中。我会调查的，你是对的。只需将引用设置为dir，该dir具有库的Wasm版本，它现在正在链接。谢谢

dev# nm libopencv_features2d.a
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(agast.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(agast_score.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(akaze.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(bagofwords.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(blobdetector.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(brisk.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(draw.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(dynamic.cpp.o) Unexpected metadata version: 2 (Expected: 1)
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(evaluation.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(fast.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(fast_score.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(feature2d.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(gftt.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(kaze.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(AKAZEFeatures.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(KAZEFeatures.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(fed.cpp.o) Unexpected metadata version: 2 (Expected: 1)
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(nldiffusion_functions.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(keypoint.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(main.cpp.o) Unexpected metadata version: 2 (Expected: 1)
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(matchers.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(mser.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(orb.cpp.o) Bad section type
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm: error: libopencv_features2d.a(opencl_kernels_features2d.cpp.o) Unexpected metadata version: 2 (Expected: 1)

target_link_libraries(MyCV /Users/dev/Documents/_Git/opencv/build_wasm/3rdparty/lib/libzlib.a)