Build failure with cxx14 and root7 enabled

[Reik]

---

ROOT Version: https://github.com/root-project/root/tree/v6-16-00-patches
OS : Manjaro
GCC : 7.4
CUDA 10
Python 3.7.2

---

[ 72%] Generating G__Core.cxx, ../../lib/libCore.rootmap
In file included from input_line_9:154:
/home/reik/Downloads/root/build1/include/ROOT/RIntegerSequence.hxx:89:8: error: redefinition of 'integer_sequence'
struct integer_sequence {
       ^
/usr/lib/gcc/x86_64-pc-linux-gnu/7.4.1/include/c++/utility:319:12: note: previous definition is here
    struct integer_sequence
           ^
In file included from input_line_9:154:
/home/reik/Downloads/root/build1/include/ROOT/RIntegerSequence.hxx:115:7: error: type alias template redefinition with different types ('__make_integer_sequence<_Tp, _Np>' (aka 'typename __make_integer_sequence_checked<type-parameter-0-0, _Ep>::type') vs
      'typename _Make_integer_sequence<_Tp, _Num>::__type')
using make_integer_sequence = __make_integer_sequence<_Tp, _Np>;
      ^
/usr/lib/gcc/x86_64-pc-linux-gnu/7.4.1/include/c++/utility:340:11: note: previous definition is here
    using make_integer_sequence
          ^
Error: /home/reik/Downloads/root/build1/core/rootcling_stage1/src/rootcling_stage1: compilation failure (/home/reik/Downloads/root/build1/lib/libCore8b9d60e61c_dictUmbrella.h)
make[2]: *** [core/base/CMakeFiles/G__Core.dir/build.make:459: core/base/G__Core.cxx] Error 1
make[1]: *** [CMakeFiles/Makefile2:19013: core/base/CMakeFiles/G__Core.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
[ 72%] Built target Cling
make: *** [Makefile:152: all] Error 2

I got the above error while building ROOT from source(the v6-16-00-patches branch) with c++14 and root7 enabled.

[pamputt]

This is not possible for now. More information here:

Cyclic dependency in module 'ROOTGraphicsPrimitives' in ROOT 6.16

Hi @pamputt, It is known issue which filed in Jira issue: https://sft.its.cern.ch/jira/browse/ROOT-9409 and expected to fixed in 6.16.02. For time being can you please try without root7 option?(e.g.-Droot7=OFF) Cheers, Oksana.

[oshadura]

@Reik, @pamputt ,

This is different issue, since my reply was about build with runtime C++ modules (-Druntime_cxxmodules=ON).

[eguiraud]

Hi @pamputt,
building with cxx14 is in fact the only way to get ROOT7

@Reik this errors usually appear when you build ROOT with the c++11 standard, and later you re-build, from the same build directory, specifying c++14. ROOT’s CMake is not able to do the late C++ standard swtich.

Building ROOT from an empty build directory should fix it.

[Reik]

To be on the safe side, I removed the entire root directory (including the build directory). I downloaded the source files and built it again(in an empty build directory).
I got the same error.

[eguiraud]

Alright, what is the exact cmake configuration command you are giving? And can you confirm that include/RConfigure.h in the build directory contains the line

#undef R__HAS_STD_INDEX_SEQUENCE

?

[amadio]

Are you adding -std=c++14 by hand to CXXFLAGS? To compile ROOT with C++14, you should call CMake with -Dcxx14=ON with 6.16.00, or -DCMAKE_CXX_STANDARD=14 with later versions (CMake’s way of configuring it).

[Reik]

@eguiraud

The cmake configuration command I am using is - cmake -Dbuiltin_lz4=ON -Dbuiltin_lzma=ON -Dbuiltin_tbb=ON -Dbuiltin_zlib=ON -Dcuda=ON -Dcxx11=OFF -Dcxx14=ON -Dpyroot_experimental=ON -Dqt=ON -Dqt5web=ON -Droot7=ON -Dtmva-gpu=ON ..

Yes, include/RConfigure.h contains the line #undef R__HAS_STD_INDEX_SEQUENCE

@amadio

No, I am not adding -std=c++14 by hand to CXXFLAGS. I am using -Dcxx14=ON.

[eguiraud]

Uhm i don’t see anything particularly out of place.
From an empty build directory, can you try just cmake -Droot7=ON path/to/root/source and then make?

If this works (root7 implies cxx14) you can work from there, adding options until it breaks.
If that doesn’t work… there’s something we are missing.

[Reik]

It seems like the -Dqt5web flag was causing the issue.

[eguiraud]

Are you sure? That’s odd, as far as I can tell that flag is completely harmless.
Can you copy-paste the minimal cmake configuration command that breaks ROOT compilation (when starting from an empty build directory)?

We need to be able to reproduce the problem to take a closer look.

[Reik]

The build completed successfully with all the flags I posted above.
This must have been some error on my side. It might have been because of a conflict with a previous installation - which I removed before performing this build (but, I did not source those files from my bashrc and they were simply present in my system in /usr/ so I am not sure why this error occurred).
Anyhow it is working perfectly now and all is good

Thanks.