[bloak]

Yes. I think the right way to do it is probably with "git log --first-parent", which will give you a linear history, and the linear history will contain only merge commits provided your project was configured to allow only merge commits. However, if you also allow squash or rebase merging then the linear history from "git log --first-parent" may contain commits that are not merges and will show the details of any PR that was rebase-merged. So, if you're going to allow merge commits at all, perhaps that's an argument for allowing only merge commits.

There's also "git log --merges" but that would presumably show any merge commits that happen to be present in a branch that is being merged so it wouldn't necessarily be linear.

If you disallow merge commits on GitHub, does that prevent a merge commit from being introduced as part of a rebase merge? If it doesn't, then presumably the only way to guarantee a linear history on GitHub is to allow only squash merging.

So, if you don't trust your developers to always do the right thing perhaps you should either only allow merge commits or only allow squash merging?

[alxmng]

Good points. Ideally, I prefer a workflow where features are branches and merged in, with fast forwarding disabled and rebasing used to keep feature branches updated. History is preserved, a linear history exists as merge commits, and merge commits also map cleanly to PRs.