How to achieve `git --no-ff --ff-only` which is not allowed

Question

As part our rebase-heavy workflow, I am hoping to use a merge on the master branch. In particular I want to merge only when the topic branch has been rebased onto the most r

Answer 1

git config alias.mff '!mff() { git merge --ff-only "$1" && git reset --hard HEAD@{1} && git merge --no-ff "$1"; }; mff'

and from then on

git mff other-branch