eb20e63f5a
When deleting a branch, "git branch -d" has a safety check that ensures the branch is merged to its upstream (if any), or to HEAD. To do that, naturally we try to resolve HEAD to a commit object. If we're on an orphan branch (i.e., HEAD points to a branch that does not yet exist), that will fail, and we'll bail with an error: $ git branch -d to-delete fatal: Couldn't look up commit object for HEAD This usually isn't that big of a deal. The deletion would fail anyway, since the branch isn't merged to HEAD, and you'd need to use "-D" (or "-f"). And doing so skips the HEAD resolution, courtesy of67affd5173(git-branch -D: make it work even when on a yet-to-be-born branch, 2006-11-24). But there are still two problems: 1. The error message isn't very helpful. We should give the usual "not fully merged" message, which points the user at "branch -D". That was a problem even back in67affd5173. 2. Even without a HEAD, these days it's still possible for the deletion to succeed. After67affd5173, commit99c419c915(branch -d: base the "already-merged" safety on the branch it merges with, 2009-12-29) made it OK to delete a branch if it is merged to its upstream. We can fix both by removing the die() in delete_branches() completely, leaving head_rev NULL in this case. It's tempting to stop there, as it appears at first glance that the rest of the code does the right thing with a NULL. But sadly, it's not quite true. We end up feeding the NULL to repo_is_descendant_of(). In the traditional code path there, we call repo_in_merge_bases_many(). It feeds the NULL to repo_parse_commit(), which is smart enough to return an error, and we immediately return "no, it's not a descendant". But there's an alternate code path: if we have a commit graph with generation numbers, we end up in can_all_from_reach(), which does eventually try to set a flag on the NULL commit and segfaults. So instead, we'll teach the local branch_merged() helper to treat a NULL as "not merged". This would be a little more elegant in in_merge_bases() itself, but that function is called in a lot of places, and it's not clear that quietly returning "not merged" is the right thing everywhere (I'd expect in many cases, feeding a NULL is a sign of a bug). There are four tests here: a. The first one confirms that deletion succeeds with an orphaned HEAD when the branch is merged to its upstream. This is case (2) above. b. Same, but with commit graphs enabled. Even if it is merged to upstream, we still check head_rev so that we can say "deleting because it's merged to upstream, even though it's not merged to HEAD". Without the second hunk in branch_merged(), this test would segfault in can_all_from_reach(). c. The third one confirms that we correctly say "not merged to HEAD" when we can't resolve HEAD, and reject the deletion. d. Same, but with commit graphs enabled. Without the first hunk in branch_merged(), this one would segfault. Reported-by: Martin von Zweigbergk <martinvonz@google.com> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Taylor Blau <me@ttaylorr.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-<commandname>.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.txt
(man gitcvs-migration or git help cvs-migration if git is
installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission and Documentation/CodingGuidelines).
Those wishing to help with error message, usage and informational message
string translations (localization l10) should see po/README.md
(a po file is a Portable Object file that holds the translations).
To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org (not the Git list). The mailing list archives are available at https://lore.kernel.org/git/, http://marc.info/?l=git and other archival sites.
Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks