How do I import root classes when using cmake?

AdvaitDhingra · April 23, 2021, 1:46pm

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ROOT Version: Latest as of April the 23rd
Platform: Ubuntu 20.04
Compiler: CMake

I am trying to create a ROOT project using cmake. Everything is working fine, I just was wondering how I can import for example “TVector3.h” into my main .cxx file? When I try it, it says the file was not found. I followed this tutorial and everything compiled successfully.

Here is my main .cxx file:

#include <iostream>

#include "HeatSim.h"

int main() {

  TVector3 *test = new TVector3(1, 2, 3);


  std::cout << test->X() << std::endl;


  return 0;
}

in the HeatSim.h file i have written `include “TVector3.h” ´

bellenot · April 23, 2021, 1:56pm

You must call thisroot.sh before calling CMake/make, in order to have ${ROOTSYS}/include in your include PATH
And you might have to add

include(${ROOT_USE_FILE})
include_directories(${ROOT_INCLUDE_DIRS} ${CMAKE_SOURCE_DIR})
link_directories(${ROOT_LIBRARY_DIR})

in your CMakeLists.txt

AdvaitDhingra · April 23, 2021, 2:13pm

Ah yes, this seems to be working. However now (with the same code as above), it is giving me a new error:

usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `main':
HeatSim.cxx:(.text+0x5e): undefined reference to `TObject::operator delete(void*)'
/usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `__static_initialization_and_destruction_0(int, int)':
HeatSim.cxx:(.text+0xcd): undefined reference to `TVersionCheck::TVersionCheck(int)'
/usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `TObject::operator new(unsigned long)':
HeatSim.cxx:(.text._ZN7TObjectnwEm[_ZN7TObjectnwEm]+0x18): undefined reference to `TStorage::ObjectAlloc(unsigned long)'
/usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `TObject::TObject()':
HeatSim.cxx:(.text._ZN7TObjectC2Ev[_ZN7TObjectC5Ev]+0x13): undefined reference to `vtable for TObject'
/usr/bin/ld: HeatSim.cxx:(.text._ZN7TObjectC2Ev[_ZN7TObjectC5Ev]+0x52): undefined reference to `TObject::fgObjectStat'
/usr/bin/ld: HeatSim.cxx:(.text._ZN7TObjectC2Ev[_ZN7TObjectC5Ev]+0x66): undefined reference to `TObject::AddToTObjectTable(TObject*)'
/usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `TVector3::TVector3(double, double, double)':
HeatSim.cxx:(.text._ZN8TVector3C2Eddd[_ZN8TVector3C5Eddd]+0x2e): undefined reference to `vtable for TVector3'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/HeatSimulation.dir/build.make:84: HeatSimulation] Error 1
make[1]: *** [CMakeFiles/Makefile2:80: CMakeFiles/HeatSimulation.dir/all] Error 2
make: *** [Makefile:84: all] Error 2

I tried to fix this by adding ROOT::Core to my target_link_libraries in CMakeLists.txt, but the error persists. What can I do?

bellenot · April 23, 2021, 2:18pm

Try with target_link_libraries(${PROJECT_NAME} ${ROOT_LIBRARIES})

AdvaitDhingra · April 23, 2021, 2:39pm

When I do this I get:

CMake Error at CMakeLists.txt:19 (target_link_libraries):
  Cannot specify link libraries for target "heatsim" which is not built by
  this project.

when I add PUBLIC in between the two I get the same error as above.

bellenot · April 23, 2021, 2:41pm

Did you replace ${PROJECT_NAME} by your real target name (heatsim maybe) ?

AdvaitDhingra · April 23, 2021, 3:23pm

Yes, but then I am greeted with the error from above:

usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `main':
HeatSim.cxx:(.text+0x5e): undefined reference to `TObject::operator delete(void*)'
/usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `__static_initialization_and_destruction_0(int, int)':
HeatSim.cxx:(.text+0xcd): undefined reference to `TVersionCheck::TVersionCheck(int)'
/usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `TObject::operator new(unsigned long)':
HeatSim.cxx:(.text._ZN7TObjectnwEm[_ZN7TObjectnwEm]+0x18): undefined reference to `TStorage::ObjectAlloc(unsigned long)'
/usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `TObject::TObject()':
HeatSim.cxx:(.text._ZN7TObjectC2Ev[_ZN7TObjectC5Ev]+0x13): undefined reference to `vtable for TObject'
/usr/bin/ld: HeatSim.cxx:(.text._ZN7TObjectC2Ev[_ZN7TObjectC5Ev]+0x52): undefined reference to `TObject::fgObjectStat'
/usr/bin/ld: HeatSim.cxx:(.text._ZN7TObjectC2Ev[_ZN7TObjectC5Ev]+0x66): undefined reference to `TObject::AddToTObjectTable(TObject*)'
/usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `TVector3::TVector3(double, double, double)':
HeatSim.cxx:(.text._ZN8TVector3C2Eddd[_ZN8TVector3C5Eddd]+0x2e): undefined reference to `vtable for TVector3'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/HeatSimulation.dir/build.make:84: HeatSimulation] Error 1
make[1]: *** [CMakeFiles/Makefile2:80: CMakeFiles/HeatSimulation.dir/all] Error 2
make: *** [Makefile:84: all] Error 2

AdvaitDhingra · April 23, 2021, 3:37pm

After doing some digging, I think the problem may be that i’m not linking against libCore. How would I do this (if this is indeed the problem)?

bellenot · April 23, 2021, 4:37pm

Try to add libCore (or Core) in target_link_libraries

AdvaitDhingra · April 23, 2021, 4:39pm

No change. Still the same error

bellenot · April 23, 2021, 4:39pm

Please provide something we can try

AdvaitDhingra · April 23, 2021, 4:40pm

Here is my CMakeLists.txt file at the moment:

   cmake_minimum_required(VERSION 3.0 FATAL_ERROR)
   project(heatsim)


   find_package(ROOT 6.16 CONFIG REQUIRED)

   include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)

   include(${ROOT_USE_FILE})
   include_directories(${ROOT_INCLUDE_DIRS} ${CMAKE_SOURCE_DIR})
   link_directories(${ROOT_LIBRARY_DIR})

   add_library(HeatSim)
   root_generate_dictionary(G__HeatSim HeatSim.h MODULE HeatSim LINKDEF HeatSimLinkDef.h)


   target_link_libraries(HeatSim PUBLIC ${ROOT_LIBRARIES} Core)

   add_executable(HeatSimulation HeatSim.cxx)

Maybe you can spot the new error? Sorry this is taking so long

Or maybe you can try it on your own system?

bellenot · April 23, 2021, 4:59pm

First of all, G__HeatSim.cxx is missing from add_executable

add_executable(HeatSimulation HeatSim.cxx G__HeatSim.cxx)

And do you have a ClassDef() in your class definition?

eguiraud · April 23, 2021, 6:08pm

You need to pass the dictionary and link the libraries to your executable:

add_executable(HeatSimulation HeatSim.cxx G__HeatSim.cxx)
target_link_libraries(HeatSimulation Core)

Unrelated, but

add_library(HeatSim)

does not seem to do anything.

AdvaitDhingra · April 23, 2021, 6:15pm

Okay, I have done this but am still getting the error.

when I remove that line the cmake . command fails.

AdvaitDhingra · April 23, 2021, 6:19pm

Ahh never mind, when I do this

add_executable(HeatSimulation HeatSim.cxx G__HeatSim.cxx)
target_link_libraries(HeatSimulation Core)

The initial error goes away, however, I then get this one which is more specific to what I am doing:

[ 14%] Building CXX object CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o
[ 28%] Linking CXX executable HeatSimulation
/usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `TVector3::TVector3(double, double, double)':
HeatSim.cxx:(.text._ZN8TVector3C2Eddd[_ZN8TVector3C5Eddd]+0x2e): undefined reference to `vtable for TVector3'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/HeatSimulation.dir/build.make:112: HeatSimulation] Error 1
make[1]: *** [CMakeFiles/Makefile2:80: CMakeFiles/HeatSimulation.dir/all] Error 2
make: *** [Makefile:84: all] Error 2

For refrence, here is my HeatSim.cxx file:

#include <iostream>

#include "HeatSim.h"
#include "TVector3.h"

int main() {

  TVector3 *test = new TVector3(1, 2, 3);

  std::cout << test->X() << std::endl;

  return 0;
}

AdvaitDhingra · April 23, 2021, 6:21pm

Okay, I fixed it by simply adding Physics to target_link_libraries . It’s working now! Thank you both for your help!! Have a nice weekend

AdvaitDhingra · April 23, 2021, 6:43pm

@eguiraud @bellenot terribly sorry to bother you again, but when I try to create a TGraph or a TCanvas I get something like this:

/usr/bin/ld: CMakeFiles/HeatSimulation.dir/HeatSim.cxx.o: in function `main':
HeatSim.cxx:(.text+0x76): undefined reference to `TCanvas::TCanvas(char const*, char const*, int, int)'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/HeatSimulation.dir/build.make:112: HeatSimulation] Error 1
make[1]: *** [CMakeFiles/Makefile2:80: CMakeFiles/HeatSimulation.dir/all] Error 2
make: *** [Makefile:84: all] Error 2

How can I fix this?
I have imported TPad.h and TCanvas.h in the header file

EDIT: I fixed it. Forgot to import Gpad

eguiraud · April 23, 2021, 7:03pm

undefined reference to.. is not a missing #include, it’s a missing linked library. In this case, you need Gpad I think.

AdvaitDhingra · April 23, 2021, 7:04pm

Yes, I did this and I am getting no errors now. Is there a way to make the TCanvas appear in a window? Like when running a normal ROOT project?