[SOLVED] Undefined refenrece after importing static library in C

Undefined refenrece after importing static library in C

I have a static library built from another project and I want to use it in new project. My CMakeLists.txt:

cmake_minimum_required(VERSION 3.0)

project(smah)
add_library(lotrlib STATIC IMPORTED)
set_target_properties(lotrlib PROPERTIES IMPORTED_LOCATION ${CMAKE_SOURCE_DIR}/libs/libdmggameserver.a)
set_target_properties(lotrlib PROPERTIES INTERFACE_INCLUDE_DIRECTORIES /home/plomba/dmg/dmglib/gtgameserver)
add_executable(smah main.cpp)
target_link_libraries(smah lotrlib)

install(TARGETS smah RUNTIME DESTINATION bin)

and my main.cpp:

#include <iostream>
#include "onetorulethemall.h"

int main(int argc, char **argv) {
    const double inputValue = std::stod(argv[1]);
    
    std::cout << inputValue << std::endl;
    serveDarkLordMelkor();    
    return 0;
}

The directory '/home/plomba/dmg/dmglib/gtgameserver' does contain onetorulethemall.h file and this file does declare function 'serveDarkLordMelkor()'

But when I try to build this I get

/home/plomba/projects/smah/main.cpp:8: undefined reference to `serveDarkLordMelkor()

also I see #include "onetorulethemall.h" in red in my IDE saying that file was not found and serveDarkLordMelkor is not suggested in autocompletion when I start typing it

Solution

The problem was in mixing C and C++ code. The included libdmggameserver.a is written in C and so its header had to be wrapped in


#ifdef __cplusplus
extern "C" {
#endif

...header file content...

#ifdef __cplusplus
}
#endif