inattentively squash all commits of a topic branch (i.e. no need to open an editor as in rebase -i)

git-autosquash

#!/bin/bash
set -euo pipefail
target_branch=$1
current_branch=$(git rev-parse --abbrev-ref head)
squash_branch=${current_branch}_work
git checkout -B ${squash_branch} ${target_branch}
git merge --squash ${current_branch}
git commit -am "squashed"
git checkout ${current_branch}
git reset --hard ${squash_branch}
git branch -D ${squash_branch}