How to "git show" a merge commit with combined diff output even when every changed file agrees with one of the parents?

Question

Look at the commit message:

commit 0e1329e551a5700614a2a34d8101e92fd9f2cad6 (HEAD, master)
Merge: fc17405 ee2de56
Author: Tilman Vogel <email@email>
Date:   Tue Feb 22 00:27:17 2011 +0100

Merge branch 'testing' into master

notice the line:

Merge: fc17405 ee2de56

take those two commit ids and reverse them. so in order get the diff that you want, you would do:

git diff ee2de56...fc17405

to show just the names of the changed files:

git diff --name-only ee2de56..fc17405

and to extract them, you can add this to your gitconfig:

exportfiles = !sh -c 'git diff $0 --name-only | "while read files; do mkdir -p \"$1/$(dirname $files)\"; cp -vf $files $1/$(dirname $files); done"'

then use it by doing:

git exportfiles ee2de56..fc17405 /c/temp/myproject

A better solution (mentioned by @KrisNuttycombe):

git diff fc17405...ee2de56

for the merge commit:

commit 0e1329e551a5700614a2a34d8101e92fd9f2cad6 (HEAD, master)
Merge: fc17405 ee2de56
Author: Tilman Vogel <email@email>
Date:   Tue Feb 22 00:27:17 2011 +0100

to show all of the changes on ee2de56 that are reachable from commits on fc17405. Note the order of the commit hashes - it's the same as shown in the merge info: Merge: fc17405 ee2de56

Also note the 3 dots ... instead of two!

For a list of changed files, you can use:

git diff fc17405...ee2de56 --name-only

You can create branch with HEAD set to one commit before merge. Then, you can do:

git merge --squash testing

This will merge, but not commit. Then:

git diff

If you are sitting at the merge commit then this shows the diffs:

git diff HEAD~1..HEAD

If you're not at the merge commit then just replace HEAD with the merge commit. This method seems like the simplest and most intuitive.

Seems like answered here: https://public-inbox.org/git/[email protected]/

So in a similar way, running

$ git diff --cc $M $M^1 $M^2 $(git merge-base $M^1 $M^2)

should show a combined patch that explains the state at $M relative to the states recorded in its parents and the merge base.

I think you just need 'git show -c $ref'. Trying this on the git repository on a8e4a59 shows a combined diff (plus/minus chars in one of 2 columns). As the git-show manual mentions, it pretty much delegates to 'git diff-tree' so those options look useful.