I have used ClearCase in the past, as well as subversion, bazaar, mercurial, git, and Team Foundation Server. When I used ClearCase, we used UCM, and one of the features that I really liked was the ability to break out software by components, and set and recommend baselines on those components.
I have a current need for similar functionality. We have a library used on multiple products, but when developers make changes, they are typically working on one product. They may change the interface or functionality that impacts other products, but it is not practical for one developer to integrate and test changes for all products. Rather, I'd like to have that developer do their work on their product, recommend a new baseline, and then when it is appropriate, other developers may pick up the work of integrating the changes to another product.
I would like the VCS to support that workflow. I would like to consider alternatives to ClearCase, if they exist. I'm quite familiar with the "challenges" of implementing ClearCase. I'm not trying to start an opinion piece -- I just want to know if any other VCS supports this functionality (or if anyone has developed their own tools or process to emulate this with another VCS), and how to implement it.
I don't think tags in svn (or equivalent in other VCS offerings) are the answer. In ClearCase, when you recommend a new baseline, it prevented developers from working on the old baseline -- they were forced to rebase, and continue work from the new baseline. I don't know how to force that rebase operation in any other VCS.
I could put the library in its own repo, but that causes other problems. I still need a way to specify (for builds, releases, developer "check outs"), which version/tag/baseline to use, and having this part of the VCS is very useful for tracking purposes.