git/reset.c, branch v2.36.2

Merge branch 'pw/use-in-process-checkout-in-rebase'

2022-02-18T21:53:27Z

Use an internal call to reset_head() helper function instead of spawning "git checkout" in "rebase", and update code paths that are involved in the change. * pw/use-in-process-checkout-in-rebase: rebase -m: don't fork git checkout rebase --apply: set ORIG_HEAD correctly rebase --apply: fix reflog reset_head(): take struct rebase_head_opts rebase: cleanup reset_head() calls create_autostash(): remove unneeded parameter reset_head(): make default_reflog_action optional reset_head(): factor out ref updates reset_head(): remove action parameter rebase --apply: don't run post-checkout hook if there is an error rebase: do not remove untracked files on checkout rebase: pass correct arguments to post-checkout hook t5403: refactor rebase post-checkout hook tests rebase: factor out checkout for up to date branch

rebase --apply: set ORIG_HEAD correctly

2022-01-26T20:08:53Z

At the start of a rebase, ORIG_HEAD is updated to the tip of the branch being rebased. Unfortunately reset_head() always uses the current value of HEAD for this which is incorrect if the rebase is started with "git rebase " as in that case ORIG_HEAD should be updated to . This only affects the "apply" backend as the "merge" backend does not yet use reset_head() for the initial checkout. Fix this by passing in orig_head when calling reset_head() and add some regression tests. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano

rebase --apply: fix reflog

2022-01-26T20:08:53Z

move_to_original_branch() passes the message intended for the branch reflog as `orig_head_msg`. Fix this by adding a `branch_msg` member to struct reset_head_opts and add a regression test. Note that these reflog messages do not respect GIT_REFLOG_ACTION. They are not alone in that and will be fixed in a future series. The "merge" backend already has tests that check both the branch and HEAD reflogs. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano

reset_head(): take struct rebase_head_opts

2022-01-26T20:08:53Z

This function takes a confusingly large number of parameters which makes it difficult to remember which order to pass them in. The following commits will add a couple more parameters which makes the problem worse. To address this change the function to take a struct of options. Using a struct means that it is no longer necessary to remember which order to pass the parameters in and anyone reading the code can easily see which value is passed to each parameter. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano

reset_head(): make default_reflog_action optional

2022-01-26T20:08:53Z

This parameter is only needed when a ref is going to be updated and the caller does not pass an explicit reflog message. Callers that are only discarding uncommitted changes in the working tree such as such as "rebase --skip" or create_autostash() do not update any refs so should not have to worry about passing this parameter. This change is not intended to have any user visible changes. The pointer comparison between `oid` and `&head_oid` checks that the caller did not pass an oid to be checked out. As no callers pass RESET_HEAD_RUN_POST_CHECKOUT_HOOK without passing an oid there are no changes to when the post-checkout hook is run. As update_ref() only updates the ref if the oid passed to it differs from the current ref there are no changes to when HEAD is updated. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano

reset_head(): factor out ref updates

2022-01-26T20:08:53Z

In the next commit we will stop trying to update HEAD when we are removing uncommitted changes from the working tree. Move the code that updates the refs to its own function in preparation for that. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano

reset_head(): remove action parameter

2022-01-26T20:08:53Z

The only use of the action parameter is to setup the error messages for unpack_trees(). All but two cases pass either "checkout" or "reset". The case that passes "reset --hard" would be better passing "reset" so that the error messages match the builtin reset command like all the other callers that are doing a reset. The case that passes "Fast-forwarded" is only updating HEAD and so the parameter is unused in that case as it does not call unpack_trees(). The value to pass to setup_unpack_trees_porcelain() can be determined by checking whether flags contains RESET_HEAD_HARD without the caller having to specify it. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano

rebase --apply: don't run post-checkout hook if there is an error

2022-01-26T20:08:53Z

The hook should only be run if the worktree and refs were successfully updated. This primarily affects "rebase --apply" but also "rebase --merge" when it fast-forwards. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano

rebase: do not remove untracked files on checkout

2022-01-26T20:08:52Z

If "git rebase [--apply|--merge] " detects that is an ancestor of then it will fast-forward and checkout . Normally a checkout or picking a commit during a rebase will refuse to overwrite untracked files, however rebase does overwrite untracked files when checking out . The fix is to only set reset in `unpack_tree_opts` if flags contains `RESET_HEAD_HARD`. t5403 may seem like an odd home for the new test but it will be extended in the next commit to check that the post-checkout hook is not run when the checkout fails. The test for `!detach_head` dates back to the original implementation of reset_head() in ac7f467fef ("builtin/rebase: support running "git rebase "", 2018-08-07) and was correct until e65123a71d ("builtin rebase: support `git rebase

`", 2018-09-04) started using reset_head() to checkout when fast-forwarding. Note that 480d3d6bf9 ("Change unpack_trees' 'reset' flag into an enum", 2021-09-27) also fixes this bug as it changes reset_head() to never remove untracked files. I think this fix is still worthwhile as it makes it clear that the same settings are used for detached and non-detached checkouts. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano

rebase: pass correct arguments to post-checkout hook

2022-01-26T20:08:52Z

If a rebase started with "rebase [--apply|--merge] " detects that is an ancestor of then it fast-forwards and checks out . Unfortunately in that case it passed the null oid as the first argument to the post-checkout hook rather than the oid of HEAD. A side effect of this change is that the call to update_ref() which updates HEAD now always receives the old value of HEAD. This provides protection against another process updating HEAD during the checkout. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano