Getting Potential Closure Details Before Building

Currently for my build process, I use morph to deploy, and then after a switch, I run nix profile diff-closures --profile /nix/var/nix/profiles/system. This tells me the size of various parts of my closure (less important to me) and the version bumps and changes to all packages changed by this.

I would, in fact, like to know before I run any build, not just how many packages will be built, but what individual versions will be bumped and what differences there are from the current closure. Is there some magic nix command I don’t yet know to evaluate and compare my configuration and locally pinned nixpkgs to the current configuration and give me
discord: 0.0.26 → 0.0.27, libcap: 2.67 → 2.68, etc?

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@MindmeshLink Did you ever find an answer to this?

I think this would be great to have so I don’t have to spend half an hour fetching/building updates to find out what the updates will be. dry-build output shows what derivations will be built, but it doesn’t say why, and it doesn’t show them as differences from the current setup.

Also, it would be great to have something like this so I know what will happen when I make changes to my NixOS configuration. For example, I just reorganized my config files a bit, but the exact same configuration should be the result. However, a dry-build shows that 224 derivations will be built. I have no idea why, because the end result should be the same.

Unfortunately I didn’t! I’m still definitely interested in it, though.