gcc/g++ 4.9 no longer supported by Canonical

[ktaherig]

The current version (at the time of my writing this) is 9.3.0. When I tried
sudo apt -f install gcc-4.9 g++-4.9
It gave the following:

Package gcc-4.9 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

Package g++-4.9 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'gcc-4.9' has no installation candidate
E: Package 'g++-4.9' has no installation candidate

Apparently, it hasn't been supported in years.

[nagadomi]

Does it say anywhere that it depends on gcc 4.9?
If you are having problems installing torch7 on Ubuntu 20.04, see the following issue.
Install on Ubuntu20.04: nagadomi/distro#12