https://root.cern/root-7 - - on this page a command is given to help build root 7, it should be slightly modified as, it is not building root 7 experimental files properly.
I found this command working
cmake -DCMAKE_CXX_STANDARD=14 - DROOT7=True path/to/root/source
Instead of this command
cmake -DCMAKE_CXX_STANDARD=14 path/to/root/source.
welcome to the ROOT forum and sorry for the delay.
@amadio or @Axel might know whether
-DCMAKE_CXX_STANDARD=14 should set
-DROOT7=True (like the docs seem to imply) or it is required to specify it explicitly.
You don’t need
-DROOT7=true, the option is called
-Droot7=True and gets enabled by default when you use C++14 and above (which is a requirement to enable it).