Include path from root-config semi complete?

_ROOT Version: 6.14/04
Platform: linux
Compiler: gcc 8.2.0

It occured to me that root headers are nowadays in
${CMAKE_INSTALL_PREFIX}/include/root and not anymore in
${CMAKE_INSTALL_PREFIX}/include, while still being included as #include "TF1.h" and not #include "root/TF1.h". Now that’s fine, and root-config --cflags prints out a -I flag with the trailing root.

But, when one installs VecCore along with root, these do end up in
${CMAKE_INSTALL_PREFIX}/include, which may not be in any standard -I path.


  1. build and install root with -Dbuiltin_veccore=ON -Dveccore=ON -DCMAKE_INSTALL_PREFIX=/home/pseyfert/root-install-and-nothing-else.

  2. create a tiny c++ file echo '#include "TF1.h"' > main.cpp.

  3. set up a build environment export CPPFLAGS=$(root-config --cflags); export CXX=$(root-config --cxx) (linkage not needed).

  4. use gnu make builtin rules to compile make main.o
    (results in c++ -pthread -std=c++1z -m64 -fdiagnostics-color -march=native -O3 -g -Wextra -Wall -Wshadow -I/home/pseyfert/root-install-and-nothing-else/include/root -c -o main.o main.cpp for me)

the compilation then fails because of

In file included from /home/pseyfert/root-install-and-nothing-else/include/root/TFormula.h:24,
                 from /home/pseyfert/root-install-and-nothing-else/include/root/TF1.h:27,
                 from main.cpp:1:
/home/pseyfert/root-install-and-nothing-else/include/root/Math/Types.h:22:10: fatal error: VecCore/VecCore: No such file or directory
 #include <VecCore/VecCore>
compilation terminated.
make: *** [<builtin>: main.o] Error 1

Not overly happy with this, but unsure if I should file that under ‘unfortunate corner case’, ‘bug’, ‘new-version-migration-task’ or something else.

(root_numpy doesn’t build for me atm because of this :/)

(for what concerns building root_numpy. its build framework respects ${CPPFLAGS} so one can bodge the build through environment vars)

PPS: it seems to me I also run into this problem with cmake when following

Hi, thanks for reporting this. The <prefix>/include/root is used when -Dgnuinstall=ON is passed to cmake. In any case, I do think that we should add the includes for builtins that get installed along with ROOT to the flags ROOT needs, although I do not really like such usage of builtins. If you wouldn’t mind, could you please file a JIRA issue with this same information? Thank you!

Indeed, flipping -Dgnuinstall=OFF I get a setup that works better.

Thanks for creating the issue. Note that if your library directory is lib64, the gnuinstall=OFF setup may not work correctly. I hope to fix that sometime soon as well. Cheers,

Thanks for the warning. My library directory is lib so looks like I’m not affected by that.

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