Hi @diaj, and welcome to the community!
It seems that
libstdc++5 is no longer available in the repos (The
compat-libstdc++-33.i686 package you also mentioned would contain it, but that’s only in CentOS 6/7).
Generally, you can find out which packages (if any) provide a file you’re looking for by using
dnf repoquery --whatprovides like so:
# libstdc++5 x86_64
$ dnf repoquery --whatprovides /usr/lib64/libstdc++.so.5
# libstdc++5 i686
$ dnf repoquery --whatprovides /usr/lib/libstdc++.so.5
If a package contains that file, dnf will give you the package name. Here for example is the output when looking for libstdc++ 6 on my system:
$ dnf repoquery --whatprovides /usr/lib64/libstdc++.so.6
so I know that installing the
libstdc++ package would give me the library I’m looking for.