如何使用Visual Studio git集成查看合并提交中更改的文件

Question

I'm using the visual studio git integration and trying to see which files were changed in a merge commit.

Say I am looking at the history of my dev branch and I have merged from master into dev. If I look at the merge commit, it shows the files I have edited in dev; what I want to see is the changes I have merged from master (in command-line terms I think what I'm looking for is "git show -m --first-parent").

Is there any way to achieve this with the visual studio integration? failing that, are there any free tools that would list the changed files and then be able invoke my standard git difftool to see the individual changes.

Answer 1

Viewing the changes in a merge commit can be approached in several ways.

• Diff with ALL parents – One common approach is to diff a merge commit with all of its parents. Any change that can be found in at least one parent is not a change in that merge commit, so merge commits will frequently show as empty unless there were conflicts that had to be resolved.

• Diff with FIRST parent – Another common approach is to diff a merge commit only with its first parent. The idea is if merging topic->master, then master will be the first parent. Diffing against master will then show all changes that flowed in from the topic branch in this merge.

• Let the user pick – Allow diffing with all parents or choosing a specific parent.

To see this difference in merge commit display, here's an example using the diff-tree command.

• "git diff-tree -m < merge_commit_id >" – This command will show the changes against individual parents. The merge commit will not appear to be empty.

• "git diff-tree -c < merge_commit_id >" – The -c option instructs Git to "list only files which were modified from all parents". This command will show no changes in the merge commit unless a conflict resolution or other change was made directly in the merge commit.

The current behavior in VS 2017's Commit Details view is to diff with all parents of a merge commit. We have found through user feedback that this is the option that is least confusing to users since it is a consistent view regardless of the direction of the merge. In a future update, hopefully the feature will be enhanced to also support selecting an individual parent against which to diff.

As a workaround, another option is to use VS 2017's Compare Commits feature.

1. View the history of your dev branch.
2. (optional) Click the toolbar button for "Show First Parent Only".
3. Select the merge commit and the parent against which to diff. In first parent mode, this will be the next commit in the list.
4. Right click and choose Compare Commits.

Hope this helps!