/usr/share/doc/cpp-x86_64-linux-gnux32/README.Bugs is in gcc-x86-64-linux-gnux32 4:7.3.0-3ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/cpp-x86_64-linux-gnux32/../gcc-7-x86_64-linux-gnux32-base/README.Bugs