ROOT Development version fails to compile

The recently released ROOT 6.09/02 fails to compile with the error message in the attached file (too long to fit here).root compile error.txt (49.5 KB)


Did you run cmake twice, enabling c++14 in the second invocation of cmake?

It seems that the configuration is confused about which features are provided by your compiler, and which features need to be provided by ROOT. That traditionally only happens for inconsistent cmake runs…

Here is what I would do: delete the build directory, configure with cmake with c++14 enabled, build.

Cheers, Axel

I tried that, and it still gives the same error.

The errors about std::string_view in particular suggest ROOT may be expecting C++17 for some reason.

Can you send

  • the details about your OS: distro and version, GCC version is 6.3.0? And the version of CMake
  • the commands you used to configure ROOT and the output of cmake during the initial configuration
  • the file CMakeCache.txt



Distro: Archlinux
GCC 6.3.1
CMake 3.7.2

Configured with ccmake switching to cxx14 (instead of cxx11), python3 (instead of python) and setting ReleaseType to Optimized.
CMakeCache.txt (121.8 KB)

How/when did you switch? Switching an existing build area from one C++ version to the other does not work and lead to errors similar to yours (i.e. the test that ‘check what works with the requested version and compiler’ are not re-run and the first one is kept (but is now wrong).


Your CMakeCache.txt seems to agree with our suspicion: it does not show the test results for any string_view test, maybe because it was skipped as c++14 was disabled during the initial cmake run.


Yep, seems you were right.

In order to get ccmake to pick up the valid configuration options, I have to configure with no options. It seems this was the cmake run causing problems (despite not generating build files at this point). It all works if I configure with cmake.

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