Hi @Neel_Shah ,
as a side note in general there is no need to build from source to get ROOT running on WSL. You should be able to use the pre-compiled binaries or the conda/snap packages, see Complete ROOT Installation Instructions for WSL (Ubuntu 18.04 on Windows 10) .
If you have to build from source: as Lorenzo said please make sure it’s the latest v6-26-00-patches or the latest master branch (you might have to git pull). We do not see those compilation errors with those branches, they built correctly in the nightly builds.
Cheers,
Enrico