我正在尝试将大型主文件中的某些类重构为单独的头文件和 cpp 文件,并且在链接时出现 undefined reference 错误。
我有一个看起来像这样的项目:
├── CMakeLists.txt
├── data
│ └── ICING BE SI Data.csv
├── gcc
│ ├── CMakeCache.txt
│ ├── CMakeFiles
│ ├── cmake_install.cmake
│ ├── lib
│ ├── Makefile
│ ├── src
│ └── tmp
├── include
│ ├── Interpolator.hpp
│ ├── InverseCDFProcess.hpp
│ └── XYParser.hpp
├── lib
│ ├── CMakeLists.txt
│ ├── Interpolator.cpp
│ ├── InverseCDFProcess.cpp
│ └── XYParser.cpp
└── test
└── test_icing.cpp
该项目有几个类,
Interpolator
和 InverseCDFProcess
,我最近从主可执行文件 test_icing.cpp
给自己的.cpp
和 .hpp
文件,位于 lib
和 include
目录,分别。由于这些类确实相互依赖(
InverseCDFProcess
需要 Interpolator
,而后者又需要 XYParser.cpp
中的函数),我决定将它们构建为静态库,然后在编译时链接到主可执行文件。它们是这样构建的:
add_library(xyparser STATIC XYParser.cpp)
add_library(interpolator STATIC Interpolator.cpp)
add_library(inversecdf STATIC InverseCDFProcess.cpp)
然后我以正常方式将这些库链接到我的可执行文件中:
include_directories(include)
link_directories(lib)
link_directories(include) # Do I need this?
add_executable(test_icing test/test_icing.cpp)
# ... some code adding an external library which works fine
target_link_libraries(test_icing inversecdf interpolator xyparser ${external_library_name})
这会产生这个链接命令:
/usr/bin/c++ CMakeFiles/test_icing.dir/test/test_icing.cpp.o -o test_icing -L/mnt/c/Users/foo/projects/chase-icing/lib -L/mnt/c/Users/foo/projects/chase-icing/include -L/mnt/c/Users/foo/projects/chas
e-icing/gcc/src/imtc-build/lib -Wl,-rpath,/mnt/c/Users/foo/projects/chase-icing/lib:/mnt/c/Users/foo/projects/chase-icing/include:/mnt/c/Users/foo/projects/chase-icing/gcc/src/imtc-build/lib lib/libinversecdf
.a lib/libinterpolator.a lib/libxyparser.a -limt
此时编译停止并出现错误:
/mnt/c/Users/foo/projects/chase-icing/test/test_icing.cpp:(.text+0xcca): undefined reference to `Interpolator<double>::Interpolator(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > co
nst&)'
/mnt/c/Users/foo/projects/chase-icing/test/test_icing.cpp:(.text+0xd4c): undefined reference to `Interpolator<double>::set_bounds(std::pair<double, double> const&)'
/mnt/c/Users/foo/projects/chase-icing/test/test_icing.cpp:(.text+0xd99): undefined reference to `InverseCDFProcess<double>::InverseCDFProcess(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<
char> > const&)'
/mnt/c/Users/foo/projects/chase-icing/test/test_icing.cpp:(.text+0xdd9): undefined reference to `InverseCDFProcess<double>::generate()'
库是否建好没关系
STATIC
或 SHARED
. undefined reference 错误仍然发生。我的问题是:我错过了一些
extern
或在我的类定义或实现中类似?为什么这种相对简单的重构会导致 undefined reference ?我的链接目录不正确吗?它应该引用构建目录吗?任何帮助表示赞赏。
最佳答案
继续为 future 的人回答这个问题:
该解决方案嵌入在错误消息中:/mnt/c/Users/foo/projects/chase-icing/test/test_icing.cpp:(.text+0xdd9): undefined reference to `InverseCDFProcess<double>::generate()'
此错误表明类是模板化的。问题是我把这些模板的实现放在 .cpp
中。文件,如下所示:
├── include
│ ├── Interpolator.hpp
│ ├── InverseCDFProcess.hpp
│ └── XYParser.hpp
├── lib
│ ├── CMakeLists.txt
│ ├── Interpolator.cpp
│ ├── InverseCDFProcess.cpp
│ └── XYParser.cpp
模板需要在头文件中包含完整的实现。所以,好消息是我一开始就不需要这些库。只需
#include "Interpolator.hpp
等,它应该按预期工作!模板需要实现的原因见此处:Why can templates only be implemented in the header file?
关于c++ - 在 CMake 项目中链接静态库 - 未定义的引用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/61162765/