我如何压缩 git 中提交日期不是过去的提交？

Question

So, I have a very simple use case; I want to squash all the commits that need to go back into master from my 'todays working' branch.

Until now I've been using git rebase -i for this, but it doesn't work quite right; the timestamp on the final commit isn't right.

Here's an example of doing this:

[work1] git checkout master
Switched to branch 'master'

[work1] git rebase today
First, rewinding head to replay your work on top of it...
Fast-forwarded master to today.

[work1] git log --pretty=format:"%h%x09%an%x09%ad%x09%s"
5ad95ff Doug    Wed Nov 7 10:12:42 2012 +0800   Updated TODO again
abb891c Doug    Wed Nov 7 10:12:24 2012 +0800   Added more work
c5fd35c Doug    Wed Nov 7 10:11:50 2012 +0800   Added more work
a98facd Doug    Wed Nov 7 10:11:22 2012 +0800   Add work
b4465be Doug    Tue Nov 6 21:38:53 2012 -0800   Updated TODO
403cea9 Doug    Fri Jan 2 21:38:53 2009 -0800   Added todo

Right, now I want to squash these last four commits into one commit.

[work2] date
Wed  7 Nov 2012 10:39:39 WST

[work2] git rebase -i b4465be

pick a98facd Add work
squash c5fd35c Added more work
squash abb891c Added more work
squash 5ad95ff Updated TODO to reflect todays work

And the result:

[work2] git log
commit 3f7f1d2eb4ef23c73dce95f718152c7d5683a926
Author: Doug <doug@null.com>
Date:   Wed Nov 7 10:11:22 2012 +0800

    Add work
    Added more work
    Added more work
    Updated TODO to reflect todays work

commit b4465bee5b278214704edcfef3f6e222b5b52964
Author: Doug <doug@null.com>
Date:   Tue Nov 6 21:38:53 2012 -0800

    Updated TODO

No! That's not what I wanted. The timestamp of the resulting commit is the timestamp of the commit we squashed into; what I wanted was the new commit date to be the current time.

Just to show exactly what I'm talking about:

[work2] date
Wed  7 Nov 2012 10:39:39 WST

Author: Doug <doug@null.com>
Date:   Wed Nov 7 10:11:22 2012 +0800

I want the resulting commit to be date by the merge time, ie. now, not the time of the commit.

As far as I'm aware you can only squash down into a previous commit, not upwards into a new commit, but is there some way of doing this?

The correct solution seems to be

1. create a new commit with the merge message and the correct commit date time,
2. ??? <--- somehow squash previous commits into this one.

How do I do that?

Answer 1

Hack: You can use

git commit --amend --reset-author

The git commit man page says that this "also renews the author timestamp". You don't have to make any changes to the commit (I tried it locally), and it will update the timestamp to the current time. Definitely kind of an abuse, but it seems to work.

Answer 2

git commit --amend --date="now"

Or, if you do not want to edit the commit message:

git commit --amend --date="now" --no-edit

By default, amend will update the Committer date to the current time, but leave the Author commit date untouched.
--date="now" will also set the Author commit date to the current time.

Why does it matter if Author and Committer date are different?
When doing a git log , by default the Author date is shown ( git log --format=fuller shows the Committer date).
What may be unexpected, however, is if you use since / until it uses the Committer date, not the Author date.
This discrepancy can be a bit confusing, or lead to unexpected results.
eg: git log --since="yesterday"

--date
You can commit or amend, setting the Author date to any date:

git commit --date="Wed Apr 15 13:00 2037 -0700"
git commit --amend --date="Wed Apr 15 13:00 2037 -0700"

But, you have to use fixed dates, in a format such as ISO 8601 , or Internet Message RFC 2822 Format . YYYY.MM.DD, MM/DD/YYYY, DD.MM.YYYY will all work, but I believe a time must also be included.

source has additional options: https://alexpeattie.com/blog/working-with-dates-in-git

This SO post shows a method to set Commit and Author dates, independently, to specific dates, and on multiple commits. Though it is recommended to not change Commit dates on anything that other people use.

Answer 3

Instead of git rebase -i b4465be , copy the recent log into the clipboard and do:

git reset --soft b4465be
git commit

paste and edit the change logs, save & exit from the commit message editor.

Answer 4

How about not relying on squash and just diff an entire feature branch: http://dymitruk.com/blog/2012/02/05/branch-per-feature/