CODEWITHSUNDEEP
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Number945
Number945

Reputation: 4940

Git rebase possible bug

I am using git version 2.23.0 which is latest for MAC and I think I have found a bug in git rebase unless I am getting it wrong. The bug is not in the functionality but in the display message.

Let us use the following script to have our git history as :

  #!/bin/bash

  git init .
  echo "10" >> 1.txt && git add . && git commit -m "1"

  # Add 2 commits to master
  echo "3" >> 1.txt && git commit -am "m3"
  echo "2" >> 1.txt && git commit -am "m2"


  #checkout topic branch
  git checkout -b topic HEAD~2
  echo "1" >> 1.txt && git commit -am "t1"
  echo "2" >> 1.txt && git commit -am "t2"
  echo "1" >> 1.txt && git commit -am "t3"
  echo "2" >> 1.txt && git commit -am "t4"


  #checkout small_topic
  git checkout -b small_topic HEAD~2
  echo "1" >> 1.txt && git commit -am "s1"
  echo "2" >> 1.txt && git commit -am "s2"

  git checkout topic
  git merge small_topic
  echo "1" >> 1.txt && git commit -am "t5"
  echo "2" >> 1.txt && git commit -am "t6"

  #Show graph
  git log --oneline --all --decorate --graph

The history will look like this -

  * ea3543d (HEAD -> topic) t6
  * b57cbbc t5
  *   2d5e7d3 Merge branch 'small_topic' into topic
  |\  
  | * c94bb3b (small_topic) s2
  | * 7dab544 s1
  * | 37ae0d9 t4
  * | b667871 t3
  |/  
  * 6486a67 t2
  * 490f6d3 t1
  | * 84d8343 (master) m2
  | * f8c8abc m3
  |/  
  * 3018ae2 1

We have mainly 2 branches - master and topic. HEAD points to topic right now. On topic we created a branch small_topic which gets created from topic and in the end gets merged into it.

We want to rebase topic onto master. We run git reabse -i master topic. Now we will see this message which I think is wrong !

  pick 490f6d3 t1
  pick 6486a67 t2
  pick b667871 t3
  pick 37ae0d9 t4
  pick 7dab544 s1
  pick c94bb3b s2
  pick b57cbbc t5
  pick ea3543d t6

  # Rebase 84d8343..ea3543d onto ea3543d (8 commands)

[Please note that your SHA1 will differ from mine]

Possible Bug : Rebase 84d8343..ea3543d onto ea3543d

Why we are seeing on onto onto ea3543d ? Should not it be onto 84d8343 ? However, upon executing this rebases onto 84d8343 only.

Also, interesting thing is - if there was no small_topic branch, then the message is fine. Only when there a branch which is created from and merged into the branch to be rebased (like small_topic in topic), then only I am seeing this.

Is this a bug ?

Upvotes: 3

Views: 540

Answers (1)

torek
torek

Reputation: 487755

Yes, if you are rebasing onto master, it should say onto master or onto 84d8343.

Your command was git rebase -i master topic.

This means first, git checkout topic, then start a git rebase -i master.

This in turn means that your target (--onto argument) is defaulted from your upstream; and your upstream (commit-limiter) argument is master. So the onto should be either master (the name) or its hash ID.

This appears to be a bug in the code that generates the comments. The list of commits, whether expressed as master..topic or 84d8343..ea3543d, is correct, but the onto target is not. The occurrence of the bug is particularly weird, but probably a consequence of rewriting git rebase from shell script (which is much easier to get right) into C.

Upvotes: 5

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