链接到.a库时未定义参考

问题描述

我正在尝试该库:

https://github.com/dacap/clip

我已将其git-克隆,然后使用以下命令构建它:

cmake .
make

这将产生一个名为libclip.a的库。

现在,我已获取示例Hello World代码,即:

#include "clip/clip.h"

int main() {
  clip::set_text("Hello World");
}

鉴于以上内容位于名为 cliptest2.cpp 文件中,我将其编译如下:

g++ -lclip cliptest2.cpp -o cliptest2

每次,我得到以下信息:

/ usr / bin / ld:/tmp/cc71SQmy.o:在函数'main'中: cliptest2.cpp :(。text + 0x47):对`clip :: set_text(std :: __ cxx11 :: basic_string const&)的未定义引用 collect2:错误:ld返回1退出状态

我确实了解链接器的工作原理,并回答了数十个其他类似错误的问题。但是,鉴于我正在构建第三方库并将其链接到示例程序中,所以我不明白为什么set_text()方法没有得到解决

编辑:由于以下评论,我已经尝试了一些方法。剪辑库的源代码位于~/git/clip,我正在从主目录本身编译cliptest2.cpp。因此,根据我的环境调整@MathiasSchmid建议的命令,最终得到以下结果:

g++ cliptest2.cpp -I git -L git/clip -lclip -lxcb -lpthread -o cliptest2

我在Kubuntu 20.04 LTS上运行了此命令,并得到以下所有错误

daniel@orion:~$ g++ cliptest2.cpp -I git -L git/clip -lclip -lxcb -lpthread -o cliptest2   
/usr/bin/ld: git/clip/libclip.a(clip_x11.cpp.o): in function `clip::x11::write_data_fn(png_struct_def*,unsigned char*,unsigned long)':
clip_x11.cpp:(.text+0x4f): undefined reference to `png_get_io_ptr'
/usr/bin/ld: git/clip/libclip.a(clip_x11.cpp.o): in function `clip::x11::write_png(clip::image const&,std::vector<unsigned char,std::allocator<unsigned char> >&)':
clip_x11.cpp:(.text+0x117): undefined reference to `png_create_write_struct'
/usr/bin/ld: clip_x11.cpp:(.text+0x13a): undefined reference to `png_create_info_struct'
/usr/bin/ld: clip_x11.cpp:(.text+0x158): undefined reference to `png_destroy_write_struct'
/usr/bin/ld: clip_x11.cpp:(.text+0x17d): undefined reference to `png_set_longjmp_fn'
/usr/bin/ld: clip_x11.cpp:(.text+0x1a5): undefined reference to `png_destroy_write_struct'
/usr/bin/ld: clip_x11.cpp:(.text+0x1cb): undefined reference to `png_set_write_fn'
/usr/bin/ld: clip_x11.cpp:(.text+0x232): undefined reference to `png_set_IHDR'
/usr/bin/ld: clip_x11.cpp:(.text+0x249): undefined reference to `png_write_info'
/usr/bin/ld: clip_x11.cpp:(.text+0x255): undefined reference to `png_set_packing'
/usr/bin/ld: clip_x11.cpp:(.text+0x268): undefined reference to `png_get_rowbytes'
/usr/bin/ld: clip_x11.cpp:(.text+0x27a): undefined reference to `png_malloc'
/usr/bin/ld: clip_x11.cpp:(.text+0x3cd): undefined reference to `png_write_rows'
/usr/bin/ld: clip_x11.cpp:(.text+0x3e9): undefined reference to `png_free'
/usr/bin/ld: clip_x11.cpp:(.text+0x3fc): undefined reference to `png_write_end'
/usr/bin/ld: clip_x11.cpp:(.text+0x40f): undefined reference to `png_destroy_write_struct'
/usr/bin/ld: git/clip/libclip.a(clip_x11.cpp.o): in function `clip::x11::read_data_fn(png_struct_def*,unsigned long)':
clip_x11.cpp:(.text+0x45d): undefined reference to `png_get_io_ptr'
/usr/bin/ld: git/clip/libclip.a(clip_x11.cpp.o): in function `clip::x11::read_png(unsigned char const*,unsigned long,clip::image*,clip::image_spec*)':
clip_x11.cpp:(.text+0x575): undefined reference to `png_create_read_struct'
/usr/bin/ld: clip_x11.cpp:(.text+0x5a1): undefined reference to `png_create_info_struct'
/usr/bin/ld: clip_x11.cpp:(.text+0x5cd): undefined reference to `png_destroy_read_struct'
/usr/bin/ld: clip_x11.cpp:(.text+0x5f5): undefined reference to `png_set_longjmp_fn'
/usr/bin/ld: clip_x11.cpp:(.text+0x628): undefined reference to `png_destroy_read_struct'
/usr/bin/ld: clip_x11.cpp:(.text+0x68f): undefined reference to `png_set_read_fn'
/usr/bin/ld: clip_x11.cpp:(.text+0x6a8): undefined reference to `png_read_info'
/usr/bin/ld: clip_x11.cpp:(.text+0x6ea): undefined reference to `png_get_IHDR'
/usr/bin/ld: clip_x11.cpp:(.text+0x747): undefined reference to `png_get_rowbytes'
/usr/bin/ld: clip_x11.cpp:(.text+0x8bf): undefined reference to `png_set_strip_16'
/usr/bin/ld: clip_x11.cpp:(.text+0x8ce): undefined reference to `png_set_packing'
/usr/bin/ld: clip_x11.cpp:(.text+0x8dd): undefined reference to `png_set_expand_gray_1_2_4_to_8'
/usr/bin/ld: clip_x11.cpp:(.text+0x8ec): undefined reference to `png_set_palette_to_rgb'
/usr/bin/ld: clip_x11.cpp:(.text+0x8fb): undefined reference to `png_set_gray_to_rgb'
/usr/bin/ld: clip_x11.cpp:(.text+0x90a): undefined reference to `png_set_tRNS_to_alpha'
/usr/bin/ld: clip_x11.cpp:(.text+0x919): undefined reference to `png_set_interlace_handling'
/usr/bin/ld: clip_x11.cpp:(.text+0x938): undefined reference to `png_read_update_info'
/usr/bin/ld: clip_x11.cpp:(.text+0x95a): undefined reference to `png_malloc'
/usr/bin/ld: clip_x11.cpp:(.text+0x9ab): undefined reference to `png_malloc'
/usr/bin/ld: clip_x11.cpp:(.text+0xa19): undefined reference to `png_read_rows'
/usr/bin/ld: clip_x11.cpp:(.text+0xbe0): undefined reference to `png_free'
/usr/bin/ld: clip_x11.cpp:(.text+0xc05): undefined reference to `png_free'
/usr/bin/ld: clip_x11.cpp:(.text+0xc4b): undefined reference to `png_destroy_read_struct'
collect2: error: ld returned 1 exit status

我仍然不清楚这是什么问题。

解决方法

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