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Elijah Newren 9822175d2b Ensure index matches head before invoking merge machinery, round N
This is the bug that just won't die; there always seems to be another
form of it somewhere.  See the commit message of 55f39cf755 ("merge:
fix misleading pre-merge check documentation", 2018-06-30) for a more
detailed explanation), but in short:

<quick summary>

builtin/merge.c contains this important requirement for merge
strategies:

    ...the index must be in sync with the head commit.  The strategies are
    responsible to ensure this.

This condition is important to enforce because there are two likely
failure cases when the index isn't in sync with the head commit:

  * we silently throw away changes the user had staged before the merge

  * we accidentally (and silently) include changes in the merge that
    were not part of either of the branches/trees being merged

Discarding users' work and mis-merging are both bad outcomes, especially
when done silently, so naturally this rule was stated sternly -- but,
unfortunately totally ignored in practice unless and until actual bugs
were found.  But, fear not: the bugs from this were fixed in commit
  ee6566e8d7 ("[PATCH] Rewrite read-tree", 2005-09-05)
through a rewrite of read-tree (again, commit 55f39cf755 has a more
detailed explanation of how this affected merge).  And it was fixed
again in commit
  160252f816 ("git-merge-ours: make sure our index matches HEAD", 2005-11-03)
...and it was fixed again in commit
  3ec62ad9ff ("merge-octopus: abort if index does not match HEAD", 2016-04-09)
...and again in commit
  65170c07d4 ("merge-recursive: avoid incorporating uncommitted changes in a merge", 2017-12-21)
...and again in commit
  eddd1a411d ("merge-recursive: enforce rule that index matches head before merging", 2018-06-30)

...with multiple testcases added to the testsuite that could be
enumerated in even more commits.

Then, finally, in a patch in the same series as the last fix above, the
documentation about this requirement was fixed in commit 55f39cf755
("merge: fix misleading pre-merge check documentation", 2018-06-30), and
we all lived happily ever after...

</quick summary>

Unfortunately, "ever after" apparently denotes a limited time and it
expired today.  The merge-recursive rule to enforce that index matches
head was at the beginning of merge_trees() and would only trigger when
opt->call_depth was 0.  Since merge_recursive() doesn't call
merge_trees() until after returning from recursing, this meant that the
check wasn't triggered by merge_recursive() until it had first finished
all the intermediate merges to create virtual merge bases.  That is a
potentially HUGE amount of computation (and writing of intermediate
merge results into the .git/objects directory) before it errors out and
says, in effect, "Sorry, I can't do any merging because you have some
local changes that would be overwritten."

Trying to enforce that all of merge_trees(), merge_recursive(), and
merge_recursive_generic() checked the index == head condition earlier
resulted in a bunch of broken tests.  It turns out that
merge_recursive() has code to drop and reload the cache while recursing
to create intermediate virtual merge bases, but unfortunately that code
runs even when no recursion is necessary.  This unconditional dropping
and reloading of the cache masked a few bugs:

  * builtin/merge-recursive.c: didn't even bother loading the index.

  * builtin/stash.c: feels like a fake 'builtin' because it repeatedly
    invokes git subprocesses all over the place, mixed with other
    operations.  In particular, invoking "git reset" will reset the
    index on disk, but the parent process that invoked it won't
    automatically have its in-memory index updated.

  * t3030-merge-recursive.h: this test has always been broken in that it
    didn't make sure to make index match head before running.  But, it
    didn't care about the index or even the merge result, just the
    verbose output while running.  While commit eddd1a411d
    ("merge-recursive: enforce rule that index matches head before
    merging", 2018-06-30) should have uncovered this broken test, it
    used a test_must_fail wrapper around the merge-recursive call
    because it was known that the merge resulted in a rename/rename
    conflict.  Thus, that fix only made this test fail for a different
    reason, and since the index == head check didn't happen until after
    coming all the way back out of the recursion, the testcase had
    enough information to pass the one check that it did perform.

So, load the index in builtin/merge-recursive.c, reload the in-memory
index in builtin/stash.c, and modify the t3030 testcase to correctly
setup the index and make sure that the test fails in the expected way
(meaning it reports a rename/rename conflict).  This makes sure that
all callers actually make the index match head.  The next commit will
then enforce the condition that index matches head earlier so this
problem doesn't return in the future.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-19 10:08:03 -07:00
.github
Documentation Git 2.22.1 2019-08-11 17:41:39 -07:00
block-sha1
builtin Ensure index matches head before invoking merge machinery, round N 2019-08-19 10:08:03 -07:00
ci Merge branch 'sg/travis-gcc-4.8' 2019-07-29 12:39:13 -07:00
compat Merge branch 'js/visual-studio' 2019-08-02 13:12:02 -07:00
contrib Merge branch 'js/visual-studio' 2019-08-02 13:12:02 -07:00
ewah
git-gui
gitk-git
gitweb
mergetools
negotiator
perl
po l10n: zh_CN: for git v2.23.0 l10n round 1~2 2019-08-16 16:59:17 +08:00
ppc
refs dir-iterator: release strbuf after use 2019-08-07 12:25:35 -07:00
sha1collisiondetection@855827c583
sha1dc
sha256
t Ensure index matches head before invoking merge machinery, round N 2019-08-19 10:08:03 -07:00
templates
trace2
vcs-svn
xdiff Merge branch 'cb/xdiff-no-system-includes-in-dot-c' into maint 2019-08-09 15:18:19 -07:00
.clang-format
.editorconfig
.gitattributes Mark .bat files as requiring CR/LF endings 2019-06-20 14:03:05 -07:00
.gitignore Merge branch 'js/visual-studio' 2019-08-02 13:12:02 -07:00
.gitmodules
.mailmap .mailmap: update email address of Philip Oakley 2019-08-11 15:07:51 -07:00
.travis.yml travis-ci: build with GCC 4.8 as well 2019-07-19 14:06:01 -07:00
.tsan-suppressions
COPYING
GIT-VERSION-GEN Git 2.23 2019-08-16 10:28:23 -07:00
INSTALL
LGPL-2.1
Makefile Merge branch 'js/visual-studio' 2019-08-02 13:12:02 -07:00
README.md README: fix rendering of text in angle brackets 2019-07-18 14:47:46 -07:00
RelNotes Flush fixes up to the third batch post 2.22.0 2019-07-25 14:32:36 -07:00
abspath.c
aclocal.m4
advice.c Merge branch 'ra/cherry-pick-revert-skip' 2019-07-19 11:30:21 -07:00
advice.h Merge branch 'ra/cherry-pick-revert-skip' 2019-07-19 11:30:21 -07:00
alias.c
alias.h
alloc.c
alloc.h
apply.c apply: make parse_git_diff_header public 2019-07-11 14:29:27 -07:00
apply.h apply: make parse_git_diff_header public 2019-07-11 14:29:27 -07:00
archive-tar.c
archive-zip.c
archive.c tree-walk.c: remove the_repo from get_tree_entry() 2019-06-27 12:45:17 -07:00
archive.h
argv-array.c
argv-array.h
attr.c
attr.h
azure-pipelines.yml
banned.h
base85.c
bisect.c
bisect.h
blame.c Merge branch 'nd/tree-walk-with-repo' 2019-07-19 11:30:21 -07:00
blame.h Merge branch 'br/blame-ignore' 2019-07-19 11:30:20 -07:00
blob.c object: convert create_object() to use object_id 2019-06-20 10:20:51 -07:00
blob.h
branch.c Merge branch 'nd/switch-and-restore' 2019-07-09 15:25:44 -07:00
branch.h Merge branch 'nd/switch-and-restore' 2019-07-09 15:25:44 -07:00
builtin.h Merge branch 'ab/test-env' 2019-07-25 13:59:20 -07:00
bulk-checkin.c
bulk-checkin.h
bundle.c
bundle.h
cache-tree.c cache-tree/blame: avoid reusing the DEBUG constant 2019-06-20 14:03:05 -07:00
cache-tree.h
cache.h Merge branch 'sg/rebase-progress' into maint 2019-07-29 12:38:19 -07:00
chdir-notify.c
chdir-notify.h
check-builtins.sh
check_bindir
checkout.c
checkout.h
color.c
color.h
column.c
column.h
combine-diff.c
command-list.txt
commit-graph.c Merge branch 'ds/commit-graph-incremental' 2019-08-09 10:13:13 -07:00
commit-graph.h commit-graph: verify chains with --shallow mode 2019-06-19 20:46:26 -07:00
commit-reach.c
commit-reach.h
commit-slab-decl.h
commit-slab-impl.h
commit-slab.h
commit.c Merge branch 'ds/close-object-store' into maint 2019-07-29 12:38:22 -07:00
commit.h
common-main.c
config.c config: work around bug with includeif:onbranch and early config 2019-07-31 15:20:56 -07:00
config.h
config.mak.dev
config.mak.in
config.mak.uname vcxproj: also link-or-copy builtins 2019-07-29 14:51:43 -07:00
configure.ac
connect.c
connect.h
connected.c check_everything_connected: assume alternate ref tips are valid 2019-07-01 10:11:09 -07:00
connected.h
convert.c
convert.h
copy.c
credential-cache--daemon.c
credential-cache.c
credential-store.c
credential.c
credential.h
csum-file.c
csum-file.h
ctype.c
daemon.c
date.c
decorate.c hashmap: convert sha1hash() to oidhash() 2019-06-20 10:44:22 -07:00
decorate.h
delta-islands.c Merge branch 'jk/oidhash' 2019-07-09 15:25:43 -07:00
delta-islands.h delta-islands: respect progress flag 2019-06-20 13:29:49 -07:00
delta.h
detect-compiler
diff-delta.c
diff-lib.c
diff-no-index.c
diff.c Merge branch 'js/unmap-before-ext-diff' into maint 2019-07-29 12:38:11 -07:00
diff.h range-diff: suppress line count in outer diff 2019-07-11 14:29:27 -07:00
diffcore-break.c
diffcore-delta.c
diffcore-order.c
diffcore-pickaxe.c
diffcore-rename.c Merge branch 'jk/oidhash' 2019-07-09 15:25:43 -07:00
diffcore.h
dir-iterator.c dir-iterator: add flags parameter to dir_iterator_begin 2019-07-11 13:52:15 -07:00
dir-iterator.h dir-iterator: add flags parameter to dir_iterator_begin 2019-07-11 13:52:15 -07:00
dir.c
dir.h
editor.c pager: add a helper function to clear the last line in the terminal 2019-06-24 13:38:46 -07:00
entry.c
environment.c
exec-cmd.c
exec-cmd.h
fast-import.c Merge branch 'nd/tree-walk-with-repo' 2019-07-19 11:30:21 -07:00
fetch-negotiator.c
fetch-negotiator.h
fetch-object.c
fetch-object.h
fetch-pack.c Merge branch 'nd/fetch-capability-tweak' 2019-07-09 15:25:43 -07:00
fetch-pack.h
fmt-merge-msg.h
fsck.c Merge branch 'br/blame-ignore' 2019-07-19 11:30:20 -07:00
fsck.h
fsmonitor.c Merge branch 'cb/fsmonitor-intfix' into maint 2019-07-29 12:38:15 -07:00
fsmonitor.h
fuzz-commit-graph.c
fuzz-pack-headers.c
fuzz-pack-idx.c
generate-cmdlist.sh
gettext.c Merge branch 'ab/test-env' 2019-07-25 13:59:20 -07:00
gettext.h
git-add--interactive.perl Merge branch 'pw/add-p-recount' into maint 2019-07-29 12:38:22 -07:00
git-archimport.perl
git-bisect.sh
git-compat-util.h msvc: add a compile-time flag to allow detailed heap debugging 2019-06-25 10:46:57 -07:00
git-cvsexportcommit.perl
git-cvsimport.perl
git-cvsserver.perl
git-difftool--helper.sh
git-filter-branch.sh
git-instaweb.sh
git-legacy-stash.sh
git-merge-octopus.sh
git-merge-one-file.sh
git-merge-resolve.sh
git-mergetool--lib.sh
git-mergetool.sh
git-p4.py Merge branch 'sw/git-p4-unshelve-branched-files' into maint 2019-07-25 14:27:15 -07:00
git-parse-remote.sh
git-quiltimport.sh
git-rebase--preserve-merges.sh
git-request-pull.sh
git-send-email.perl
git-sh-i18n.sh tests: make GIT_TEST_GETTEXT_POISON a boolean 2019-06-21 09:42:49 -07:00
git-sh-setup.sh
git-submodule.sh
git-svn.perl
git-web--browse.sh
git.c Merge branch 'js/visual-studio' 2019-08-02 13:12:02 -07:00
git.rc mingw: embed a manifest to trick UAC into Doing The Right Thing 2019-06-27 12:55:45 -07:00
gpg-interface.c gpg-interface: do not scan past the end of buffer 2019-07-16 12:15:12 -07:00
gpg-interface.h
graph.c
graph.h
grep.c Merge branch 'bb/grep-pcre2-bug-message-fix' 2019-07-29 12:39:13 -07:00
grep.h
hash.h hash.h: move object_id definition from cache.h 2019-06-20 10:40:42 -07:00
hashmap.c
hashmap.h hashmap: convert sha1hash() to oidhash() 2019-06-20 10:44:22 -07:00
help.c
help.h
hex.c
http-backend.c
http-fetch.c
http-push.c object: convert lookup_object() to use object_id 2019-06-20 10:18:09 -07:00
http-walker.c
http.c
http.h
ident.c
imap-send.c
interdiff.c
interdiff.h
iterator.h
json-writer.c
json-writer.h
khash.h hashmap: convert sha1hash() to oidhash() 2019-06-20 10:44:22 -07:00
kwset.c Merge branch 'rs/copy-array' into maint 2019-07-29 12:38:15 -07:00
kwset.h
levenshtein.c
levenshtein.h
line-log.c tree-walk.c: remove the_repo from get_tree_entry() 2019-06-27 12:45:17 -07:00
line-log.h
line-range.c
line-range.h
linear-assignment.c
linear-assignment.h
list-objects-filter-options.c Merge branch 'md/list-objects-filter-parse-msgfix' 2019-06-21 11:24:10 -07:00
list-objects-filter-options.h
list-objects-filter.c Merge branch 'md/list-objects-filter-memfix' into maint 2019-07-25 14:27:12 -07:00
list-objects-filter.h
list-objects.c
list-objects.h
list.h
ll-merge.c
ll-merge.h
lockfile.c
lockfile.h
log-tree.c
log-tree.h
ls-refs.c
ls-refs.h
mailinfo.c
mailinfo.h
mailmap.c
mailmap.h
match-trees.c match-trees.c: remove the_repo from shift_tree*() 2019-06-27 12:45:17 -07:00
mem-pool.c
mem-pool.h
merge-blobs.c
merge-blobs.h
merge-recursive.c merge-recursive: remove another implicit dependency on the_repository 2019-08-19 10:08:03 -07:00
merge-recursive.h merge-recursive: introduce an enum for detect_directory_renames values 2019-08-19 10:08:03 -07:00
merge.c
mergesort.c
mergesort.h
midx.c
midx.h
name-hash.c
notes-cache.c
notes-cache.h
notes-merge.c
notes-merge.h
notes-utils.c
notes-utils.h
notes.c tree-walk.c: remove the_repo from get_tree_entry() 2019-06-27 12:45:17 -07:00
notes.h
object-store.h Merge branch 'ds/object-info-for-prefetch-fix' into maint 2019-07-25 14:27:08 -07:00
object.c Merge branch 'jk/oidhash' 2019-07-09 15:25:43 -07:00
object.h object: convert create_object() to use object_id 2019-06-20 10:20:51 -07:00
oidmap.c Merge branch 'cc/test-oidmap' 2019-07-19 11:30:19 -07:00
oidmap.h
oidset.c Merge branch 'br/blame-ignore' 2019-07-19 11:30:20 -07:00
oidset.h Merge branch 'br/blame-ignore' 2019-07-19 11:30:20 -07:00
pack-bitmap-write.c pack-bitmap: convert khash_sha1 maps into kh_oid_map 2019-06-20 10:35:05 -07:00
pack-bitmap.c pack-bitmap: convert khash_sha1 maps into kh_oid_map 2019-06-20 10:35:05 -07:00
pack-bitmap.h pack-bitmap: convert khash_sha1 maps into kh_oid_map 2019-06-20 10:35:05 -07:00
pack-check.c
pack-objects.c hashmap: convert sha1hash() to oidhash() 2019-06-20 10:44:22 -07:00
pack-objects.h pack-objects: convert packlist_find() to use object_id 2019-06-20 09:54:58 -07:00
pack-revindex.c
pack-revindex.h
pack-write.c
pack.h
packfile.c Merge branch 'ds/close-object-store' into maint 2019-07-29 12:38:22 -07:00
packfile.h Merge branch 'ds/close-object-store' into maint 2019-07-29 12:38:22 -07:00
pager.c pager: add a helper function to clear the last line in the terminal 2019-06-24 13:38:46 -07:00
parse-options-cb.c Merge branch 'nd/switch-and-restore' 2019-07-09 15:25:44 -07:00
parse-options.c
parse-options.h Merge branch 'nd/switch-and-restore' 2019-07-09 15:25:44 -07:00
patch-delta.c
patch-ids.c hashmap: convert sha1hash() to oidhash() 2019-06-20 10:44:22 -07:00
patch-ids.h
path.c
path.h
pathspec.c
pathspec.h
pkt-line.c
pkt-line.h
preload-index.c
pretty.c
pretty.h
prio-queue.c
prio-queue.h
progress.c Merge branch 'dr/progress-i18n' 2019-07-11 15:16:49 -07:00
progress.h
prompt.c
prompt.h
protocol.c
protocol.h
quote.c
quote.h
range-diff.c range-diff: add headers to the outer hunk header 2019-07-11 14:29:27 -07:00
range-diff.h
reachable.c object: convert lookup_object() to use object_id 2019-06-20 10:18:09 -07:00
reachable.h
read-cache.c Merge branch 'rs/avoid-overflow-in-midpoint-computation' into maint 2019-07-29 12:38:21 -07:00
rebase-interactive.c
rebase-interactive.h
ref-filter.c Merge branch 'ma/ref-filter-leakfix' 2019-07-19 11:30:23 -07:00
ref-filter.h
reflog-walk.c
reflog-walk.h
refs.c object: convert lookup_unknown_object() to use object_id 2019-06-20 10:06:19 -07:00
refs.h
refspec.c
refspec.h
remote-curl.c
remote-testsvn.c
remote.c
remote.h
replace-object.c
replace-object.h
repository.c
repository.h
rerere.c
rerere.h
resolve-undo.c
resolve-undo.h
revision.c Merge branch 'jk/check-connected-with-alternates' 2019-07-19 11:30:21 -07:00
revision.h
run-command.c
run-command.h
send-pack.c
send-pack.h
sequencer.c Merge branch 'pw/rebase-abort-clean-rewritten' into maint 2019-07-29 12:38:20 -07:00
sequencer.h Merge branch 'ra/cherry-pick-revert-skip' 2019-07-19 11:30:21 -07:00
serve.c
serve.h
server-info.c
setup.c
sh-i18n--envsubst.c
sha1-array.c
sha1-array.h
sha1-file.c sha1-file: release strbuf after use 2019-08-07 12:28:57 -07:00
sha1-lookup.c
sha1-lookup.h
sha1-name.c Merge branch 'nd/tree-walk-with-repo' 2019-07-19 11:30:21 -07:00
sha1dc_git.c
sha1dc_git.h
shallow.c Use the right 'struct repository' instead of the_repository 2019-06-27 12:45:17 -07:00
shell.c
shortlog.h
sideband.c
sideband.h
sigchain.c
sigchain.h
split-index.c
split-index.h
strbuf.c l10n: localizable upload progress messages 2019-07-02 12:18:49 -07:00
strbuf.h l10n: localizable upload progress messages 2019-07-02 12:18:49 -07:00
streaming.c
streaming.h
string-list.c
string-list.h
sub-process.c
sub-process.h
submodule-config.c
submodule-config.h
submodule.c
submodule.h
symlinks.c
tag.c object: convert create_object() to use object_id 2019-06-20 10:20:51 -07:00
tag.h
tar.h
tempfile.c
tempfile.h
thread-utils.c
thread-utils.h
tmp-objdir.c
tmp-objdir.h
trace.c
trace.h
trace2.c
trace2.h
trailer.c
trailer.h
transport-helper.c Merge branch 'es/local-atomic-push-failure-with-http' into maint 2019-07-29 12:38:16 -07:00
transport-internal.h
transport.c Merge branch 'es/local-atomic-push-failure-with-http' 2019-07-25 13:59:22 -07:00
transport.h object-store.h: move for_each_alternate_ref() from transport.h 2019-07-01 09:47:29 -07:00
tree-diff.c tree-walk.c: remove the_repo from fill_tree_descriptor() 2019-06-27 12:45:17 -07:00
tree-walk.c tree-walk.c: remove the_repo from get_tree_entry_follow_symlinks() 2019-06-27 12:45:17 -07:00
tree-walk.h tree-walk.c: remove the_repo from get_tree_entry_follow_symlinks() 2019-06-27 12:45:17 -07:00
tree.c object: convert create_object() to use object_id 2019-06-20 10:20:51 -07:00
tree.h
unicode-width.h Merge branch 'bb/unicode-12.1-reiwa' into maint 2019-07-25 14:27:11 -07:00
unimplemented.sh
unix-socket.c
unix-socket.h
unpack-trees.c Merge branch 'nd/tree-walk-with-repo' 2019-07-19 11:30:21 -07:00
unpack-trees.h
upload-pack.c Merge branch 'ds/close-object-store' into maint 2019-07-29 12:38:22 -07:00
upload-pack.h
url.c
url.h
urlmatch.c
urlmatch.h
usage.c
userdiff.c Merge branch 'ml/userdiff-rust' 2019-06-21 11:24:08 -07:00
userdiff.h
utf8.c
utf8.h
varint.c
varint.h
version.c
version.h
versioncmp.c
walker.c object: convert lookup_unknown_object() to use object_id 2019-06-20 10:06:19 -07:00
walker.h
wildmatch.c
wildmatch.h
worktree.c Merge branch 'nd/corrupt-worktrees' into maint 2019-07-25 14:27:07 -07:00
worktree.h
wrap-for-bin.sh
wrapper.c
write-or-die.c
ws.c
wt-status.c Merge branch 'jl/status-reduce-vertical-blank' 2019-07-19 11:30:23 -07:00
wt-status.h Merge branch 'jk/no-system-includes-in-dot-c' 2019-07-31 14:38:56 -07:00
xdiff-interface.c
xdiff-interface.h
zlib.c

README.md

Build Status

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). To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://public-inbox.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