Issue linking c++ project together with CMake

Question

Been having a little issue figuring out how to link things together with CMake and I've been stuck for three days so far. No matter what I've tried I've been having an issue in having the function returnThisClass() being undefined no matter what I've tried.

On the minimum reproducible example in headertest.cpp, there is an undefined reference to the creation of the pointer, the same error is not present on my program despite everything appearing to be a direct copy.

My file structure is

    main.cpp
    src/
        headertest.cpp
        otherheader.cpp
    lib/
        headertest.h
        otherheader.h

CMakeLists.txt

    cmake_minimum_required(VERSION 3.0.0)
    project(stackoverflowExample1 VERSION 0.1.0)
    
    include(CTest)
    enable_testing()
    
    add_library(aTest STATIC ${CMAKE_CURRENT_SOURCE_DIR}/src/otherheader.cpp ${CMAKE_CURRENT_SOURCE_DIR}/src/headertest.cpp)
    target_include_directories(aTest PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/lib/)
    
    include_directories(${CMAKE_CURRENT_SOURCE_DIR}/src/)
    
    set(
        SOURCE_FILES 
        ${CMAKE_CURRENT_SOURCE_DIR}/main.cpp
        ${CMAKE_CURRENT_SOURCE_DIR}/src/headertest.cpp
        ${CMAKE_CURRENT_SOURCE_DIR}/src/otherheader.cpp
        )   
    
    add_executable(stackoverflowExample1 ${SOURCE_FILES})
    
    target_link_libraries(stackoverflowExample1 PRIVATE aTest)
    
    set(CPACK_PROJECT_NAME ${PROJECT_NAME})
    set(CPACK_PROJECT_VERSION ${PROJECT_VERSION})
    include(CPack)

main.cpp

    #include "lib/otherheader.h"
    int main() {
        doSomethingHere();
    }

headertest.h

    namespace theTest {
    class foo1 {
        public:
            foo1();
        };
        foo1 * returnThisClass();
    }

otherheader.h

    void doSomethingHere();

headertest.cpp

    #include "../lib/headertest.h"
    
    theTest::foo1 * returnThisClass(){
        theTest::foo1 * aFoo1 = new theTest::foo1();
        return aFoo1;
    }

otherheader.cpp

    #include "../lib/otherheader.h"
    #include "../lib/headertest.h"
    
    void doSomethingHere(){
        theTest::foo1 *foo1Ptr = theTest::returnThisClass();
    }

In the duplicate question [that answer](https://stackoverflow.com/a/12574407/3440745) describes proper way for define member function in the source file. — Tsyvarev, Sep 05 '22 at 14:53

john · Answer 1 · 2022-09-05T14:45:42.180

1

Change

theTest::foo1 * returnThisClass(){

to

theTest::foo1 * theTest::foo1::returnThisClass(){

No idea about the CMake part, but the above is the first step.

edited Sep 05 '22 at 14:45

answered Sep 05 '22 at 14:43

john

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The CMake part appears to be correct. – drescherjm Sep 05 '22 at 14:44
Thank you so much! I've been running in circles for days trying to figure this out for it to be something so simple! – TheNewProgrammer Sep 05 '22 at 14:51

Issue linking c++ project together with CMake

1 Answers1