合并后Git提交消失了

Question

I'm working on a project with some collaborators, each having a remote copy of the master branch, which may or may not be up-to-date with the origin master branch.

Suppose one of the collaborators has an out-of-date copy due to a commit X , commits some Y and tries to push it to the origin branch. It fails and the collaborator merges the changes and pushes again, this time successfully.

Now, when looking at the history of the repository, commit X cannot be found anymore, except the changes of it are now in another commit called Merge branch 'master' of https://.... .

Is this normal behaviour of git? This makes tracking down changes hard. Is there something that can be done to avoid this issue?

Thanks in advance!

Answer 1

This is completely normal behavior for Git when using git merge . Git merge replaces the commits in the source branch with a single merge commit in the destination branch.

One option to preserve history is to use git rebase instead. In a rebase, your collaborator would first bring in the changes from the remote master branch, and then recommit his work on top. This would leave his local master ahead of the remote, and he can simply push his changes in. Consider the following diagram:

remote: A -- B -- C -- X
local:  A -- B -- C -- Y

After doing git rebase origin/master the diagram would look like this:

remote: A -- B -- C -- X
local:  A -- B -- C -- X -- Y'

where Y' is your collaborator's original Y commit slightly modified. Now your collaborator is in the enviable position of being able to push his work directly onto the remote master branch. After doing git push origin master from his master branch, the diagram would look like this:

remote: A -- B -- C -- X -- Y'
local:  A -- B -- C -- X -- Y'

Now your collaborator's commit appear intact in the remote master branch.