C ++:避免重复的符号链接器错误 [英] C++: Avoiding duplicate symbol linker error
问题描述
我遇到了链接器错误:
duplicate symbol __ZN5ENDF64FileILNS_7MF_enumE1EE4readEv in:
Read.cpp.o
Material.cpp.o
其中重复的符号名称为:
where the duplicate symbol name is:
$ c++filt __ZN5ENDF64FileILNS_7MF_enumE1EE4readEv
ENDF6::File<(ENDF6::MF_enum)1>::read()
我知道我无法在多个地方定义相同的函数-这可能会导致此链接器错误. (我已经看到了这个问题: ld:重复符号)我不认为我有read()
函数在多个位置定义,但链接器(clang++
)表示可以.
I know that I can't define the same function in multiple places—that's what can cause this linker error. (I've seen this question: ld: duplicate symbol) I don't think I have the read()
function defined in multiple places, but the linker (clang++
) says I do.
我在哪里复制read()
符号?
我的代码结构如下:
//MFs.hpp
#ifndef MFS_HPP
#define MFS_HPP
enum class MF_enum {
...
}
#endif
//File.hpp
#ifndef FILE_HPP
#define FILE_HPP
#include "MFs.hpp"
// Definition of class File
template<>
class File {
...
}
// Definition of File<...>::read() function
template <>
void File<1>::read()
{
std::cout << "Reading into MF=1"<< std::endl;
}
#endif
因为File
类是模板化的,所以没有File.cpp
.所有定义(和声明)都在File.hpp
There is no File.cpp
because the File
class is templated. All definitions (and declarations) are in File.hpp
// Material.cpp
#include "File.hpp"
...
// Material.hpp
#ifndef MATERIAL_HPP
#define MATERIAL_HPP
#include "File.hpp"
...
#endif
最后的驱动程序代码:
// Read.cpp
#include "Material.hpp"
#include "File.hpp"
int main (){
...
}
推荐答案
(完整的)模板专业化不是模板本身.如果要专门使用该函数,则只需在标头中声明它,并在单个翻译单元中提供实现,否则就可以内联定义:
(Complete) specializations of a template are not templates themselves. If you are specializing the function, then you need to either just declare it in the header and provide the implementation in a single translation unit, or else make the definition inline:
// Header [1]
template <int>
class File {
// ...
void open();
};
template <>
void File<1>::open(); // just declaration
// Single .cpp
template <>
void File<1>::open() { ... }
或者:
// Header [2]
template <int>
class File {
// ...
void open();
};
template <>
inline void File<1>::open() { ... }
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