flutter - 链接问题，即使 nm 在库中显示符号也找不到符号

Question

我正在链接一个应用程序到 lflutter_linux_glfw . nm工具显示它有 glad_glTexImage2D :

nm libflutter_linux_glfw.so | grep glTexImage2D
00000000034e87a0 b glad_glTexImage2D
00000000034e87a8 b glad_glTexImage2DMultisample

所以我包括了 lflutter_linux_glfw.so之前 flutter_video_renderer.o ，我得到了这个:

clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)                   
Target: x86_64-pc-linux-gnu                                             
Thread model: posix                                                     
InstalledDir: /usr/bin                                                  
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.4.0
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7       
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.4.0   
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8       
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.4.0   
Candidate multilib: .;@m64                                              
Selected multilib: .;@m64                                               
 "/usr/bin/ld" -z relro --hash-style=gnu --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o /home/dev/orwell/orwell_flutter/linux/../build/linux/debug/flutter_desktop_example
 /usr/bin/../lib/gcc/x86_64-linux-gnu/7.4.0/../../../x86_64-linux-gnu/crt1.o /usr/bin/../lib/gcc/x86_64-linux-gnu/7.4.0/../../../x86_64-linux-gnu/crti.o /usr/bin/../lib/gcc/x86_64-linux-gnu/7.4.0/crtbegin.o
 -L/home/dev/orwell/orwell_flutter/linux/../build/linux/debug/lib -L/usr/bin/../lib/gcc/x86_64-linux-gnu/7.4.0 -L/usr/bin/../lib/gcc/x86_64-linux-gnu/7.4.0/../../../x86_64-linux-gnu -L/lib/x86_64-linux-gnu
 -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu -L/usr/bin/../lib/gcc/x86_64-linux-gnu/7.4.0/../../.. -L/usr/lib/llvm-6.0/bin/../lib -L/lib -L/usr/lib -lflutter_linux_glfw
 /home/dev/orwell/orwell_flutter/linux/../build/linux/obj/main.o /home/dev/orwell/orwell_flutter/linux/../build/linux/obj/flutter/generated_plugin_registrant.o
 /home/dev/orwell/orwell_flutter/linux/../build/linux/obj//home/dev/orwell/orwell_flutter/linux/flutter/ephemeral/cpp_client_wrapper_glfw/flutter_window_controller.o
 /home/dev/orwell/orwell_flutter/linux/../build/linux/obj//home/dev/orwell/orwell_flutter/linux/flutter/ephemeral/cpp_client_wrapper_glfw/plugin_registrar.o
 /home/dev/orwell/orwell_flutter/linux/../build/linux/obj//home/dev/orwell/orwell_flutter/linux/flutter/ephemeral/cpp_client_wrapper_glfw/engine_method_result.o
 /home/dev/orwell/orwell_flutter/linux/../build/linux/obj//home/dev/orwell/orwell_flutter/linux/flutter/ephemeral/cpp_client_wrapper_glfw/standard_codec.o
 /home/dev/orwell/orwell_flutter/linux/../build/linux/obj//home/dev/orwell/orwell_flutter/common/src/flutter_video_renderer.o
 /home/dev/orwell/orwell_flutter/linux/../build/linux/obj//home/dev/orwell/orwell_flutter/common/src/flutter_texture_video_renderer.o
 /home/dev/orwell/orwell_flutter/linux/../build/linux/obj//home/dev/orwell/orwell_flutter/common/src/flutter_orwell_plugin.o "-rpath=\$ORIGIN/lib" -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc
 /usr/bin/../lib/gcc/x86_64-linux-gnu/7.4.0/crtend.o /usr/bin/../lib/gcc/x86_64-linux-gnu/7.4.0/../../../x86_64-linux-gnu/crtn.o
/home/dev/orwell/orwell_flutter/linux/../build/linux/obj//home/dev/orwell/orwell_flutter/common/src/flutter_texture_video_renderer.o: In function
`flutter_orwell_plugin::FlutterTextureVideoRenderer::renderToTexture(unsigned long, unsigned long, unsigned int)':
flutter_texture_video_renderer.cc:(.text+0x1b6): undefined reference to `glad_glTexImage2D'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [/home/dev/orwell/orwell_flutter/linux/../build/linux/debug/flutter_desktop_example] Error 1

换句话说，它提示没有对 glad_glTexImage2D 的引用。即使它确实在 flutter_linux_glfw.so .我还尝试添加 flutter_linux_glfw.so在 flutter_texture_video_renderer.o 之后但我得到同样的错误

Answer 1

nm libflutter_linux_glfw.so | grep glTexImage2D
00000000034e87a0 b glad_glTexImage2D
00000000034e87a8 b glad_glTexImage2DMultisample

这些符号是库本地的(不是从库中导出的)。

您可以通过以下方式查看导出符号列表:

nm -D libflutter_linux_glfw.so

你会发现 glad_glTexImage2D没有在那里列出。

附言

I included lflutter_linux_glfw.so before flutter_video_renderer.o

这是你应该做的相反的顺序:库应该遵循引用它们的对象(尽管这对于共享库并不重要)。