# Detecting squash-merged branches (and question about git-diff-tree) 5 messages from 2024-12-03 to 2024-12-03. Participants: Max Gautier, Kristoffer Haugsbakk. Thread: https://gitlist.dev/t/62591 ## Max Gautier, 2024-12-03 13:55 Subject: Detecting squash-merged branches (and question about git-diff-tree) Message-ID: URL: https://gitlist.dev/e/Z08N4AlQKiNi-IOI%40framework ``` Hi, I tend to work on project which do a lot of "squash-merging" e.g, merge branches by having a robot squash the branch in a new commit on top of the main branch. This makes it a bit hard to remove my branches when they are "squash-merged" (in contrast to using `git branch --merged`) I started a little script to detect such branches; initially I used git cherry, but this only detect the case where the branch has 1 commit, which is not enough. Sharing below if anyone is interested and/or want to give some feedback (warning, this is probably full of bash-ism/gnu-ism). Which leads me to my actual question: I wanted to use diff-tree in --stdin mode (instead of calling it repeatedly in a loop), feeding it my target branch and the list of relevant commits, but apparently --merge-base and --stdin are mutually exclusive. What's the reason for that ? I suppose it's related to the 3 possible line forms diff-tree accepts in --stdin mode, but I didn't find a spelled out explanation in the original thread implementing --merge-base [1]. Is there another alternative for computing the patches ids of branches in that way ? A '%(mergebase)' token for git for-each-ref would also work, but there is no such thing either that I know of. (Of course, the script as such runs ~reasonably~ well, but it does spend 95% of it's time waiting for subprocess, which bugs me a little^^) Thanks for reading me ! [1]: https://lore.kernel.org/git/cover.1599332861.git.liu.denton@gmail.com/ --- #!/bin/bash # $1 : target ref (in which we search for squashed branches) # (default: upstream/HEAD) # ${@:2} (all scripts args after the first one): git for-each-ref # patterns for refs candidates for squash-merge detection # (default: refs/{remotes/origin,heads}/} declare -A commit_by_patch_ids oldest_merge_base=${1-upstream/HEAD} ref_patterns=${@:2} ref_patterns=${ref_patterns:-refs/remotes/origin/ refs/heads/} for ref in $(git for-each-ref ${ref_patterns} \ --format='%(objectname)' \ --no-merged=${1-upstream/HEAD} ) do patch_id=( $(git diff-tree -p --merge-base ${1-upstream/HEAD} $ref \ | git patch-id --stable) ) commit_by_patch_ids[$patch_id[0]]=$ref # Caveat: # It's possible for different commit to have the save patch-id # (for instance on a feature branch do: git checkout feature;git branch # old;git rebase main -> old and feature would probably have the same # patch-id, if I understand this correctly) # proper treatment of this would need to use array of commits by # patch-id, but bash does not support multidimensional arrays. # Check oldest commit we will need to go back to when checking if a # patch-id exist in the source branch. # This assumes that branches are not squash-merged before their fork # point. This avoids going back all the way to the first commit, # which can be prohibitively expensive on repository with a long # history (e.g, linux kernel tree takes 13 minutes on a recent machine # for git log -p | git patch-id) oldest_merge_base=$(git merge-base $oldest_merge_base $ref) done declare -a squashed # Extract commits whose patch-id exist in the target branch. # for patch_id in $(git log -p ${oldest_merge_base}..${1-upstream/HEAD} \ | git patch-id --stable | cut -d ' ' -f 1) do if [[ -n "${commit_by_patch_ids[$patch_id]+exists}" ]];then squashed+=("--points-at=${commit_by_patch_ids[$patch_id]}") fi done printf "%s\n" "$(git for-each-ref $ref_patterns \ --format='%(refname:short)' \ ${squashed[@]})" -- Max Gautier ``` ## Kristoffer Haugsbakk, 2024-12-03 15:30 Subject: Re: Detecting squash-merged branches (and question about git-diff-tree) Message-ID: <75269425-49ee-4a16-beef-614da392d528@app.fastmail.com> URL: https://gitlist.dev/e/75269425-49ee-4a16-beef-614da392d528%40app.fastmail.com In-Reply-To: ``` Hi Max On Tue, Dec 3, 2024, at 14:55, Max Gautier wrote: > Hi, > > I tend to work on project which do a lot of "squash-merging" e.g, merge > branches by having a robot squash the branch in a new commit on top of > the main branch. > > This makes it a bit hard to remove my branches when they are > "squash-merged" (in contrast to using `git branch --merged`) > > > I started a little script to detect such branches; initially I used git > cherry, but this only detect the case where the branch has 1 commit, > which is not enough. I’m working on a program/script to detect merged/squashed/rebased (or cherry-picked) refs. Is it okay if I contact you if I finish it? ;) There’s also this program which says it can do the same thing (not tried): https://github.com/foriequal0/git-trim My program tries to be like a for-each-ref for merged etc. refs. More focused on reporting first since that can then be used for deletion or whatever else. ``` ## Max Gautier, 2024-12-03 15:51 Subject: Re: Detecting squash-merged branches (and question about git-diff-tree) Message-ID: URL: https://gitlist.dev/e/Z08o-O5eiu_ZsYrp%40framework In-Reply-To: <75269425-49ee-4a16-beef-614da392d528@app.fastmail.com> ``` > I’m working on a program/script to detect merged/squashed/rebased (or > cherry-picked) refs. Is it okay if I contact you if I finish it? ;) Feel free to, yes > > There’s also this program which says it can do the same thing (not tried): > > https://github.com/foriequal0/git-trim > > My program tries to be like a for-each-ref for merged etc. refs. > More focused on reporting first since that can then be used for > deletion or whatever else. Hum, I'm wondering why it didn't find this earlier, I did search though. It apparently use git commit-tree to create a temporary commit, and git cherry on that to check if it's in the target branch. I wonder if this wouldn't cause problems in case of conflicts though, during the git commit-tree process ? -- Max Gautier ``` ## Max Gautier, 2024-12-03 16:18 Subject: Re: Detecting squash-merged branches (and question about git-diff-tree) Message-ID: URL: https://gitlist.dev/e/Z08vUxoyK67LXZc3%40framework In-Reply-To: ``` Uh, btw, there is a typo in the script in the previous email, it should actually be: commit_by_patch_ids[${patch_id[0]}]=$ref on line 20 (instead of $patch_id[0]) Not sure how I ended up sending the wrong version. -- Max Gautier ``` ## Kristoffer Haugsbakk, 2024-12-03 17:42 Subject: Re: Detecting squash-merged branches (and question about git-diff-tree) Message-ID: <95b88ece-8188-46aa-b263-61bb371e4293@app.fastmail.com> URL: https://gitlist.dev/e/95b88ece-8188-46aa-b263-61bb371e4293%40app.fastmail.com In-Reply-To: ``` On Tue, Dec 3, 2024, at 16:51, Max Gautier wrote: >> My program tries to be like a for-each-ref for merged etc. refs. >> More focused on reporting first since that can then be used for >> deletion or whatever else. > > Hum, I'm wondering why it didn't find this earlier, I did search though. > It apparently use git commit-tree to create a temporary commit, and git > cherry on that to check if it's in the target branch. > I wonder if this wouldn't cause problems in case of conflicts though, > during the git commit-tree process ? Maybe, I haven’t tried. But using something that creates a commit in the DB seems a bit unnecessary/excessive in any case. Your diff approach seems more direct. -- Kristoffer Haugsbakk ```