gitgit-resetunstagegit-restore

What is `git restore` and how is it different from `git reset`?

When I want to unstage a staged file, all of my Git tutorials show something like:

$ git add *
$ git status
On branch master
Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

    renamed:    README.md -> README
    modified:   CONTRIBUTING.md

This hint tells us to use git reset for unstaging a staged file.

But instead, in my terminal, I see:

git status
On branch master
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
    renamed:    cat.js -> catcat.js
    renamed:    tolendo.gogo -> tolendo.txt

Untracked files:
  (use "git add <file>..." to include in what will be committed)
    readme (copy).md
    tolendo (copy).txt
    zing (copy).html

My terminal tells me to use git restore --staged but the tutorials, as well as Git’s website, tell me to use git reset HEAD.

I have no idea about the new restore command. I tried Google to find the difference between git reset and git restore but nothing seemed to fit my question.

Solution

  • I have presented git restore (which is still marked as "experimental") in "How to reset all files from working directory but not from staging area?", with the recent Git 2.23 (August 2019).

    It helps separate git checkout into two commands:

    As reset, restore and revert documentation states:

    There are three commands with similar names: git reset, git restore and git revert.

    • git-revert is about making a new commit that reverts the changes made by other commits.
    • git-restore is about restoring files in the working tree from either the index or another commit.
      This command does not update your branch.
      The command can also be used to restore files in the index from another commit.
    • git-reset is about updating your branch, moving the tip in order to add or remove commits from the branch. This operation changes the commit history.
      git reset can also be used to restore the index, overlapping with git restore.

    So:

    To restore a file in the index to match the version in HEAD (this is the same as using git-reset)

    git restore --staged hello.c

    or you can restore both the index and the working tree (this the same as using git-checkout)

    git restore --source=HEAD --staged --worktree hello.c

    or the short form which is more practical but less readable:

    git restore -s@ -SW hello.c

    With Git 2.25.1 (Feb. 2020), "git restore --staged" did not correctly update the cache-tree structure, resulting in bogus trees to be written afterwards, which has been corrected.

    See discussion.

    See commit e701bab (08 Jan 2020) by Jeff King (peff).
    (Merged by Junio C Hamano -- gitster -- in commit 09e393d, 22 Jan 2020)

    restore: invalidate cache-tree when removing entries with --staged

    Reported-by: Torsten Krah
    Signed-off-by: Jeff King

    When "git restore --staged " removes a path that's in the index, it marks the entry with CE_REMOVE, but we don't do anything to invalidate the cache-tree.
    In the non-staged case, we end up in checkout_worktree(), which calls remove_marked_cache_entries(). That actually drops the entries from the index, as well as invalidating the cache-tree and untracked-cache.

    But with --staged, we never call checkout_worktree(), and the CE_REMOVE entries remain. Interestingly, they are dropped when we write out the index, but that means the resulting index is inconsistent: its cache-tree will not match the actual entries, and running "git commit" immediately after will create the wrong tree.

    We can solve this by calling remove_marked_cache_entries() ourselves before writing out the index. Note that we can't just hoist it out of checkout_worktree(); that function needs to iterate over the CE_REMOVE entries (to drop their matching worktree files) before removing them.

    One curiosity about the test: without this patch, it actually triggers a BUG() when running git-restore:

    BUG: cache-tree.c:810: new1 with flags 0x4420000 should not be in cache-tree

    But in the original problem report, which used a similar recipe, git restore actually creates the bogus index (and the commit is created with the wrong tree). I'm not sure why the test here behaves differently than my out-of-suite reproduction, but what's here should catch either symptom (and the fix corrects both cases).

    With Git 2.27 (Q2 2020), "git restore --staged --worktree" now defaults to take the contents out of "HEAD", instead of erring out.

    See commit 088018e (05 May 2020) by Eric Sunshine (sunshineco).
    (Merged by Junio C Hamano -- gitster -- in commit 4c2941a, 08 May 2020)

    restore: default to HEAD when combining --staged and --worktree

    Signed-off-by: Eric Sunshine
    Reviewed-by: Taylor Blau

    By default, files are restored from the index for --worktree, and from HEAD for --staged.

    When --worktree and --staged are combined, --source must be specified to disambiguate the restore source, thus making it cumbersome to restore a file in both the worktree and the index.

    (Due to an oversight, the --source requirement, though documented, is not actually enforced.)

    However, HEAD is also a reasonable default for --worktree when combined with --staged, so make it the default anytime --staged is used (whether combined with --worktree or not).

    So now, this works:

    git restore --staged --worktree
git restore -SW