How to get git log -p to show changes in merge commits

This leads me to believe that git log -p doesn't show merged changes? How to get this feature?

You are correct: by default, git log -pyou are shown merge commits, but they don't even try to show diffs.

As odradek wrote in the comments , adding that -coption will make the combined diffgit log show . You can also use (note, two dashes , as opposed to one dash ), which also shows the combined diff, or , which effectively splits the merge for diff purposes , and shows each parent against that parent a difference.--cc--cc-c-m

These three options can be used with git show. However, for whatever reason, the git show default is --ccwhile , and the default git logis empty .

The difference between these three options is only clear when doing certain merges, it's a little tricky to show them. However, we can make one thing clear: diffs of any combination only show files that differ from all parents. That said, whatever is shown is trimmed to git show -chelpgit show --cc you. (Depending on what --cccan be displayed, the table may be more than trimmed -c. I don't have an example handy, though.)

For example, consider committing 3e5c63943d35be1804d302c0393affc4916c3dc3to Git in a Git repository . This is a merge (with parent c13c783...and 20690b2..., if we run two separate git diff commands, we can see that only two files have changed compared to its first parent :

$ git diff --name-status 3e5c639^1 3e5c639
M       builtin/remote.c
M       t/t5505-remote.sh

But many files (including the same two files) changed compared to the second parent file :

$ git diff --name-status 3e5c639^2 3e5c639 | expand
M       .gitignore
M       .mailmap
M       Documentation/Makefile
A       Documentation/RelNotes/2.12.0.txt
M       Documentation/SubmittingPatches
A       Documentation/asciidoctor-extensions.rb
M       Documentation/blame-options.txt
M       Documentation/cat-texi.perl
M       Documentation/config.txt
M       Documentation/diff-config.txt
[snipped here - but the same two files do appear in the 339-entry list]

If I git show --ccrely on that, then I don't get any diff list at all. If I run git show -cit, I get a diff listed builtin/remote.cand t/t5505-remote.sh.

If I git show -mprocess this, I get two separate git diffmanifests. Nor is it a "combination difference". The first starts with:

commit 3e5c63943d35be1804d302c0393affc4916c3dc3 (from
 c13c783c9d3d7d3eff937b7bf3642d2a7fe32644)

and only show the first two files. The second starts with:

commit 3e5c63943d35be1804d302c0393affc4916c3dc3 (from
 20690b213975ad3e9b1bc851f434d818bd2d1de9)

and shows all 339 files.

Use -mis "a real big hammer", but you'll need a lot of sorting work to accomplish many tasks. Using --ccor -cis usually sufficient.

(Something else you might need to do when making such changes using .js git log -pis adding --full-historyto ensure that bothgit log branches are followed after every merge . This is only needed if you're simplifying the history by adding options .)-- <path>