CODEWITHSUNDEEP
git
Puggan Se
Puggan Se

Reputation: 5846

Can I see if 2 commits patches are the same

If one branch have commits A-B-C and another branch have commits A-C'-B', is there some way to make a hash of the patches of B and B'? I want to (script a) compare of 2 branches, and report the differences, so in the case above I want it to notice they are the same. If I use log between C and B' will show 2 commits, even if they are the same commits in another order.

Tested to do some diffs betweens git show, but as the line numbers differs, and I don't know how to get them to be equal.

Here is a script to set up a git test-case:

git init
seq 1 50 > a
git add a
git commit -m "fill a"

git checkout -b top_bottom
sed -i '1 a\
Add this line high up in the file' a
git add a
git commit -m "top of a"
sed -i '$ a\
Add this line at the bottom of the file' a
git add a
git commit -m "bottom of a"
git checkout master

git checkout -b bottom_top
git cherry-pick top_bottom
git cherry-pick top_bottom~
git checkout master

Doing a compare like diff <(git show --format=raw top_bottom) <(git show --format=raw bottom_top~1) show line-number diffs in the patch part (and expected hashes differences in the header)

Upvotes: 2

Views: 381

Answers (2)

torek
torek

Reputation: 488183

You want git patch-id, which is designed for exactly this purpose.

I had to modify your setup script slightly for FreeBSD sed (change sed -i '1a\ to sed -i -e '1a\) but having done so:

$ git show bottom_top | git patch-id --stable
3a28b42e4aae9c248c00c63451756cbd881cf046 2c33ad0a41076e5a47ec780e8ab6c6b8450db582
$ git show top_bottom~1 | git patch-id --stable
3a28b42e4aae9c248c00c63451756cbd881cf046 7cd871013b7bbfc69f03315d43285a2b78b81a86

The first number is the patch ID (you may use either --stable or --unstable; read the documentation to decide which to use) and the second is the commit hash. Note that top_bottom produces a different patch ID (from, of course, a different commit):

$ git show top_bottom | git patch-id --stable
69febc37e58b8aeb210b3e1e71fa59a11c369a74 9a34efdfe098f6b690199a124cc3ce34f48002b8

Upvotes: 5

LeGEC
LeGEC

Reputation: 51850

To compare patches, I would rather use git diff :

git diff B^ B > B.patch

Taking back your example :

# name B1 and B2 the 2 commits you want to inspect :
git tag B1 top_bottom^
git tag B2 bottom_top

Get the pacthes :

# first patch :
git diff B1^ B1 > B1.patch
# second patch :
git diff B2^ B2 > B2.patch

The blunt comparison will still show the differences in line numbers :

diff B1.patch B2.patch

An approximation would be : drop the lines mentionning line numbers, and see if the simple "added / removed" blocks match :

cat B1.patch |
  grep -v "^index" |  # remove lines which mention blob or tree hashes
  grep -v "^@@"       # remove lines which mention line numbers
    > B1.trimmed

# same with B2

diff B1.trimmed B2.trimmed

Upvotes: 2

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