CMake issue with Cairo or libX11

Hi guys!

CMake issue with Cairo or libX11

Hi guys!

I am new here and intend to frequent these forums both to answer questions and look for help when needed.

Right now I am teaching myself CMake along with C and C Sharp. I have already been using C++ for a while.

Right now though, I am having an issue with CMake and Cairo Graphics Library and libX11. I have a program I started, when I build I get this message:

Undefined reference to symbol ‘XOpenDisplay’


This is the line of code that generates that error:
Display* d = XOpenDisplay(NULL);

I update CMake with:
cmake -S . -B build/

When I do this it consistently tells me that it is successfully finding the libraries for cairo and libX11, those being:

libXext.so and libXext.so

This leads me to believe that there is something I need to do with my CMakeLists.txt that I am not seeing. I have looked all over, researched to death and am at a loss, so now I am posting for help. I am attaching my CMakeLists.txt

I am using Arch Linux, my IDE is KDevelop. Thank you in advance.

The symbol is resolved by libX11.so

Code:

---

$ nm -D /usr/lib/x86_64-linux-gnu/libXext.so | grep XOpenDisplay
$ nm -D /usr/lib/x86_64-linux-gnu/libX11.so | grep XOpenDisplay
000000000002d370 T XOpenDisplay

---

FindX11 — CMake 3.22.0-rc1 Documentation

I would try finding the X11 and then linking the libraries.

X11_LIBRARIES

You could try only changing

Code:

---

${PROJECT_NAME} ${EXTRA_LINKS} glfw ${GLEW_LIBRARIES} GL GLU ${Cairo_LIBRARIES}

---

to

Code:

---

${PROJECT_NAME} ${EXTRA_LINKS} glfw ${GLEW_LIBRARIES} GL GLU ${Cairo_LIBRARIES} ${X11_LIBRARIES}

---

But, I am thinking the find is needed to set X11_LIBRARIES

Tim S.

Thanks. I just tried that, still getting the same error.

UPDATE:

I can now get a successful build with g++ Source/main.cpp -lX11

Now I am learning to do this with CMake

Solved:

This solved it:

Code:

---

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -lX11")

---

you guys were very helpful in getting me to look in the right direction on things.