target filtered dependencies present in the workspace are not supported by split mode hack
I'm not sure what this means; would it be worth rewriting the error message? If there is a particular dependency creating the incompatibility with the tool, maybe it's helpful to print it so the user can figure out how their setup is strange?
This happened for me on https://github.com/a-b-street/abstreet/blob/master/Cargo.toml.
Super awesome tool; thank you for creating it! I remember puzzling through the rough equivalent of cargo hackerman dupes back in https://old.reddit.com/r/rust/comments/cqceu4/common_crates_in_cargo_workspace_recompiled/. Your tool will save me loads of time going forward.
I got curious and checked the source; looks like the problem is
[target.'cfg(unix)'.dependencies]
termion = "1.5.6"
and similar.
I guess dependencies per target complicate things... any way to fix the target to unix when running the analysis? Even if it breaks the other targets a bit, could be possible for the user to manually fix things up.
The problem is not with the analysis but with applying the results to Cargo.toml files. You can try using cargo hackerman hack --dry - it will do the analysis in a usual way but instead of saving the results it will print them out.