Bryce Schober (bryce-schober): I had a very similar issue, but on 16.04 and wanting gcc-7. Adding the the toolchain ppa made gcc-5 subject to upgrading, triggering this issue. I managed to deal with it with package pinning and aptitude (see comment 58).
Here are a few more details if in case you want to try this yourself (I recommend using Timeshift or similar in case you want to go back).
Bryce Schober (bryce-schober): I had a very similar issue, but on 16.04 and wanting gcc-7. Adding the the toolchain ppa made gcc-5 subject to upgrading, triggering this issue. I managed to deal with it with package pinning and aptitude (see comment 58).
Here are a few more details if in case you want to try this yourself (I recommend using Timeshift or similar in case you want to go back).
$ cat /etc/apt/ preferences. d/toolchain. pref ubuntu- toolchain- r-test
Package: *
Pin: release o=LP-PPA-
Pin-Priority: 60
Here are some quick instructions on how to use aptitude: https:/ /makandracards. com/makandra/ 47558-how- to-install- packages- from-newer- ubuntu- releases# planning- the-upgrade