Lib gcc dependency problem

I'm running Ubuntu 14.04.3, and the unity-editor-5.1.0f3+2015082501_amd64 package has a dependency on lib32stdc++6 that can't be easily resolved without significant downgrades.

The root of the problem seems to be that it creates a dependency chain that would force a downgrade of the gcc-4.9-base package from 4.9.2 to 4.9.1.

I haven't run all the way down that rabbithole yet because I'm concerned about causing instability on my work machine, but at my earliest opportunity I'll see if I can figure out what's what on another machine and report back, unless someone else already has a solution.

I do have Universe and Multiverse enabled, so maybe that is affecting things?

 

The .debs are frequently picky about version numbers (exact match wanted instead of higher than a specific version), despite it normally not being a problem for a bugfix update (third number changed). Have you tried the generic installer instead? It might be more lenient, since dynamically linked libraries are linked with less specificity about version numbers.

 

The requirement is for lib32stdc++6 (>= 4.6) - why would this force a downgrade? Or has the name of the package changed?