CLion —发行版本引起链接器错误

Question

I have a .cpp file and a corresponding .h inside a project in CLion like so:

element.h

#pragma once

#include <string>
#include <unordered_map>

enum class Element
{
    H, He,
    Li, Be, B, C, N, O, F, Ne,
    Na, Mg, Al, Si, P, S, Cl, Ar,
    K, Ca
};

class ElementHash
{
// simple hash function in operator()
};

// LINE IN QUESTION:
std::ostream& operator<<(std::ostream& out, const Element& e);

struct ElementData
{
};

extern const std::unordered_map<std::string, Element> elementObjectLookupTable;
extern const std::unordered_map<Element, ElementData, ElementHash> elementDataLoopkupTable;

std::string toString(const Element& e);

element.cpp

#include "element.h"

using namespace std;


ostream& operator<<(ostream& out, const Element& e)
{
    out << toString(e);
    return out;
}

// rest of the file's not important

These two files (along with others) are all built from a subdirectory into a .dylib which is then linked to the executable built by the main project. This .dylib builds and links just fine under the Debug build, but when I switch to release build in the IDE, I get the following linker error:

Undefined symbols for architecture x86_64:
  "std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::operator<<<char, std::__1::char_traits<char>, std::__1::allocator<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)", referenced from:
      operator<<(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, Element const&) in element.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[3]: *** [/Users/_____/ClionProjects/chemhelp/bin/Release/libchemhelp-core.dylib] Error 1
make[2]: *** [CMakeFiles/chemhelp-core.dir/all] Error 2
make[1]: *** [CMakeFiles/chemhelp-core.dir/rule] Error 2
make: *** [chemhelp-core] Error 2

I don't know if I've broken something in my project or in the settings, but for some reason the Release build is failing.

Answer 1

The error message looks like your library was compiled with a different architecture and/or build settings than the other code in your project.

Of course, try cleaning the project first.

You may need to configure your project such that:

• In your debug build, you compile the library and the main with debug settings the same, and link with the same version of the standard C++ library.
• Similarly in release, the library and main code should be using the same release flags and link against the same version of the standard C++ libraries.