函数模板的显式实例化失败（g ++） [英] explicit instantiation of function template fails (g++)

问题描述

我遇到一些问题（即链接错误）与显式实例化的功能模板。在Visual Studio下的项目链接确定，只有在g ++ / Unix下，使用Eclipse-CDT，链接产生错误。

I am experiencing some problems (i.e, linkage errors) with explicit instantiation of a function template. Under Visual Studio the project links ok, only under g++/Unix, using Eclipse-CDT, the linkage produce errors.

函数调用是静态库的一部分，它与一个动态库相连，在一个大项目中。
函数的架构如下：

The function call is a part of a static library, which is linked with a dynamic library, in a big project. The architecture of the function is as follows:

• 函数模板在我的 MathUtils.h 文件。其中一个函数参数本身是一个struct模板，它被声明为和在 h 文件（在同一命名空间下）中实现。


• 函数实现和实例化在 MathUtils.cpp 。


• 函数调用位于 someFile.cpp （当然 #includeMathUtils.h作为静态库的一部分链接。

• function template declared (but not implemented) inside a namespace in my MathUtils.h file. One of the function arguments is itself a struct template, which is declared and implemented in this h file (under the same namespace).
• function implementation and instantiation is in MathUtils.cpp.
• function call is in someFile.cpp (which of course #include "MathUtils.h") which is compiled & linked as a part of a static library.

驱动我（几乎）疯了的事情是，构建错误不完全可以重现，我怀疑Eclipse被指责（也许跳过一些步骤，虽然我在每个构建之前使用 clean project ）。

The thing that drives me (almost) crazy, is that the build errors are not fully reproducible, and I suspect the Eclipse is to be blamed (maybe skipping some steps, although I use clean project before each build).

大约一个小时，Debug配置创建了w / o错误，但是发布失败，未定义的引用... 链接错误。
然后，对于下一个小时，两个配置失败。然后我做了一个小项目，只有上面提到的3个文件，并从命令行和从Eclipse编译它 - 没有错误。现在这两个配置似乎链接确定。

For about an hour, the Debug configuration built w/o errors but the Release failed with undefined reference to... linkage error. Then, for the next hour, both configurations failed. Then I made a small project, with only the 3 files mentioned above, and compiled it both from the command line and from Eclipse - no errors at all. Now Both configurations seem to link ok.

有没有人使用Eclipse-CDT遇到类似的问题？任何建议？

Did anyone experienced similar issues using the Eclipse-CDT? Any suggestions?

编辑：因为问题不容易（或在所有）可重现，我想这将很难得到答案。如果我有任何新的见解，我会更新。

since the problem is not easily (or at all) reproducible, I guess it will be hard to get an answer. I will update if I have any new insights.

推荐答案

我有一个类似的问题。通过在 .cpp 中使用类实现移动实例化之后实现

I had a similar problem. Solved it by moving instantiation after implementation in the .cpp with the class implementation.

myclass.hpp：

myclass.hpp:

template <class T>
class MyClass
{
public:
    MyClass();
    // other declarations
};

myclass.cpp：

myclass.cpp:

#include "myclass.hpp"

template <class T>
MyClass<T>::MyClass()
{
}

template class MyClass<int>;
template class MyClass<bool>;

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