As established in the previous commit and commit b00bf1c9a8
(git-rebase: make --allow-empty-message the default, 2018-06-27), the
behavior for rebase with different backends in various edge or corner
cases is often more happenstance than design. This commit addresses
another such corner case: commits which "become empty".
A careful reader may note that there are two types of commits which would
become empty due to a rebase:
* [clean cherry-pick] Commits which are clean cherry-picks of upstream
commits, as determined by `git log --cherry-mark ...`. Re-applying
these commits would result in an empty set of changes and a
duplicative commit message; i.e. these are commits that have
"already been applied" upstream.
* [become empty] Commits which are not empty to start, are not clean
cherry-picks of upstream commits, but which still become empty after
being rebased. This happens e.g. when a commit has changes which
are a strict subset of the changes in an upstream commit, or when
the changes of a commit can be found spread across or among several
upstream commits.
Clearly, in both cases the changes in the commit in question are found
upstream already, but the commit message may not be in the latter case.
When cherry-mark can determine a commit is already upstream, then
because of how cherry-mark works this means the upstream commit message
was about the *exact* same set of changes. Thus, the commit messages
can be assumed to be fully interchangeable (and are in fact likely to be
completely identical). As such, the clean cherry-pick case represents a
case when there is no information to be gained by keeping the extra
commit around. All rebase types have always dropped these commits, and
no one to my knowledge has ever requested that we do otherwise.
For many of the become empty cases (and likely even most), we will also
be able to drop the commit without loss of information -- but this isn't
quite always the case. Since these commits represent cases that were
not clean cherry-picks, there is no upstream commit message explaining
the same set of changes. Projects with good commit message hygiene will
likely have the explanation from our commit message contained within or
spread among the relevant upstream commits, but not all projects run
that way. As such, the commit message of the commit being rebased may
have reasoning that suggests additional changes that should be made to
adapt to the new base, or it may have information that someone wants to
add as a note to another commit, or perhaps someone even wants to create
an empty commit with the commit message as-is.
Junio commented on the "become-empty" types of commits as follows[1]:
WRT a change that ends up being empty (as opposed to a change that
is empty from the beginning), I'd think that the current behaviour
is desireable one. "am" based rebase is solely to transplant an
existing history and want to stop much less than "interactive" one
whose purpose is to polish a series before making it publishable,
and asking for confirmation ("this has become empty--do you want to
drop it?") is more appropriate from the workflow point of view.
[1] https://lore.kernel.org/git/xmqqfu1fswdh.fsf@gitster-ct.c.googlers.com/
I would simply add that his arguments for "am"-based rebases actually
apply to all non-explicitly-interactive rebases. Also, since we are
stating that different cases should have different defaults, it may be
worth providing a flag to allow users to select which behavior they want
for these commits.
Introduce a new command line flag for selecting the desired behavior:
--empty={drop,keep,ask}
with the definitions:
drop: drop commits which become empty
keep: keep commits which become empty
ask: provide the user a chance to interact and pick what to do with
commits which become empty on a case-by-case basis
In line with Junio's suggestion, if the --empty flag is not specified,
pick defaults as follows:
explicitly interactive: ask
otherwise: drop
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Different rebase backends have different treatment for commits which
start empty (i.e. have no changes relative to their parent), and the
--keep-empty option was added at some point to allow adjusting behavior.
The handling of commits which start empty is actually quite similar to
commit b00bf1c9a8 (git-rebase: make --allow-empty-message the default,
2018-06-27), which pointed out that the behavior for various backends is
often more happenstance than design. The specific change made in that
commit is actually quite relevant as well and much of the logic there
directly applies here.
It makes a lot of sense in 'git commit' to error out on the creation of
empty commits, unless an override flag is provided. However, once
someone determines that there is a rare case that merits using the
manual override to create such a commit, it is somewhere between
annoying and harmful to have to take extra steps to keep such
intentional commits around. Granted, empty commits are quite rare,
which is why handling of them doesn't get considered much and folks tend
to defer to existing (accidental) behavior and assume there was a reason
for it, leading them to just add flags (--keep-empty in this case) that
allow them to override the bad defaults. Fix the interactive backend so
that --keep-empty is the default, much like we did with
--allow-empty-message. The am backend should also be fixed to have
--keep-empty semantics for commits that start empty, but that is not
included in this patch other than a testcase documenting the failure.
Note that there was one test in t3421 which appears to have been written
expecting --keep-empty to not be the default as correct behavior. This
test was introduced in commit 00b8be5a4d ("add tests for rebasing of
empty commits", 2013-06-06), which was part of a series focusing on
rebase topology and which had an interesting original cover letter at
https://lore.kernel.org/git/1347949878-12578-1-git-send-email-martinvonz@gmail.com/
which noted
Your input especially appreciated on whether you agree with the
intent of the test cases.
and then went into a long example about how one of the many tests added
had several questions about whether it was correct. As such, I believe
most the tests in that series were about testing rebase topology with as
many different flags as possible and were not trying to state in general
how those flags should behave otherwise.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When developing a script, it can be painful to understand why Git thinks
something is outside the current repo, if the current repo isn't what
the user thinks it is. Since this can be tricky to diagnose, especially
in cases like submodules or nested worktrees, let's give the user a hint
about which repository is offended about that path.
Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Acked-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The details of how credential helpers can be called or implemented were
originally covered in Documentation/technical/. Those are topics that
end users might care about (and we even referenced them in the
credentials manpage), but those docs typically don't ship as part of the
end user documentation, making them less useful.
This situation got slightly worse recently in f3b9055624 (credential:
move doc to credential.h, 2019-11-17), where we moved them into the C
header file, making them even harder to find.
So let's move put this information into the gitcredentials(7)
documentation, which is meant to describe the overall concepts of our
credential handling. This was already pointing to the API docs for these
concepts, so we can just include it inline instead.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The code to compute the commit-graph has been taught to use a more
robust way to tell if two object directories refer to the same
thing.
* tb/commit-graph-object-dir:
commit-graph.h: use odb in 'load_commit_graph_one_fd_st'
commit-graph.c: remove path normalization, comparison
commit-graph.h: store object directory in 'struct commit_graph'
commit-graph.h: store an odb in 'struct write_commit_graph_context'
t5318: don't pass non-object directory to '--object-dir'
The index-pack code now diagnoses a bad input packstream that
records the same object twice when it is used as delta base; the
code used to declare a software bug when encountering such an
input, but it is an input error.
* jk/index-pack-dupfix:
index-pack: downgrade twice-resolved REF_DELTA to die()
The code to automatically shrink the fan-out in the notes tree had
an off-by-one bug, which has been killed.
* jh/notes-fanout-fix:
notes.c: fix off-by-one error when decreasing notes fanout
t3305: check notes fanout more carefully and robustly
The way "git submodule status" reports an initialized but not yet
populated submodule has not been reimplemented correctly when a
part of the "git submodule" command was rewritten in C, which has
been corrected.
* pk/status-of-uncloned-submodule:
t7400: testcase for submodule status on unregistered inner git repos
submodule: fix status of initialized but not cloned submodules
t7400: add a testcase for submodule status on empty dirs
Some codepaths were given a repository instance as a parameter to
work in the repository, but passed the_repository instance to its
callees, which has been cleaned up (somewhat).
* mt/use-passed-repo-more-in-funcs:
sha1-file: allow check_object_signature() to handle any repo
sha1-file: pass git_hash_algo to hash_object_file()
sha1-file: pass git_hash_algo to write_object_file_prepare()
streaming: allow open_istream() to handle any repo
pack-check: use given repo's hash_algo at verify_packfile()
cache-tree: use given repo's hash_algo at verify_one()
diff: make diff_populate_filespec() honor its repo argument
The diff-* plumbing family of subcommands now pay attention to the
diff.wsErrorHighlight configuration, which has been ignored before;
this allows "git add -p" to also show the whitespace problems to
the end user.
* jk/diff-honor-wserrhighlight-in-plumbing:
diff: move diff.wsErrorHighlight to "basic" config
Some rough edges in the sparse-checkout feature, especially around
the cone mode, have been cleaned up.
* ds/sparse-checkout-harden:
sparse-checkout: fix cone mode behavior mismatch
sparse-checkout: improve docs around 'set' in cone mode
sparse-checkout: escape all glob characters on write
sparse-checkout: use C-style quotes in 'list' subcommand
sparse-checkout: unquote C-style strings over --stdin
sparse-checkout: write escaped patterns in cone mode
sparse-checkout: properly match escaped characters
sparse-checkout: warn on globs in cone patterns
sparse-checkout: detect short patterns
sparse-checkout: cone mode does not recognize "**"
sparse-checkout: fix documentation typo for core.sparseCheckoutCone
clone: fix --sparse option with URLs
sparse-checkout: create leading directories
t1091: improve here-docs
t1091: use check_files to reduce boilerplate
p4 updates.
* ld/p4-cleanup-processes:
git-p4: avoid leak of file handle when cloning
git-p4: check for access to remote host earlier
git-p4: cleanup better on error exit
git-p4: create helper function importRevisions()
git-p4: disable some pylint warnings, to get pylint output to something manageable
git-p4: add P4CommandException to report errors talking to Perforce
git-p4: make closeStreams() idempotent
Unneeded connectivity check is now disabled in a partial clone when
fetching into it.
* jt/connectivity-check-optim-in-partial-clone:
fetch: forgo full connectivity check if --filter
connected: verify promisor-ness of partial clone
A low-level API function get_oid(), that accepts various ways to
name an object, used to issue end-user facing error messages
without l10n, which has been updated to be translatable.
* jk/get-oid-error-message-i18n:
sha1-name: mark get_oid() error messages for translation
t1506: drop space after redirection operator
t1400: avoid "test" string comparisons
Allow the rebase.missingCommitsCheck configuration to kick in when
"rebase --edit-todo" and "rebase --continue" restarts the procedure.
* ag/edit-todo-drop-check:
rebase-interactive: warn if commit is dropped with `rebase --edit-todo'
sequencer: move check_todo_list_from_file() to rebase-interactive.c
Test updates.
* dl/test-must-fail-fixes-2:
t4124: only mark git command with test_must_fail
t3507: use test_path_is_missing()
t3507: fix indentation
t3504: do check for conflict marker after failed cherry-pick
t3419: stop losing return code of git command
t3415: increase granularity of test_auto_{fixup,squash}()
t3415: stop losing return codes of git commands
t3310: extract common notes_merge_files_gone()
t3030: use test_path_is_missing()
t2018: replace "sha" with "oid"
t2018: don't lose return code of git commands
t2018: teach do_checkout() to accept `!` arg
t2018: be more discerning when checking for expected exit codes
t2018: improve style of if-statement
t2018: add space between function name and ()
t2018: remove trailing space from test description
"git rebase -i" (and friends) used to unnecessarily check out the
tip of the branch to be rebased, which has been corrected.
* ag/rebase-avoid-unneeded-checkout:
rebase -i: stop checking out the tip of the branch to rebase
"git rebase -i" identifies existing commits in its todo file with
their abbreviated object name, which could become ambigous as it
goes to create new commits, and has a mechanism to avoid ambiguity
in the main part of its execution. A few other cases however were
not covered by the protection against ambiguity, which has been
corrected.
* js/rebase-i-with-colliding-hash:
rebase -i: also avoid SHA-1 collisions with missingCommitsCheck
rebase -i: re-fix short SHA-1 collision
parse_insn_line(): improve error message when parsing failed
A new version of fsmonitor-watchman hook has been introduced, to
avoid races.
* kw/fsmonitor-watchman-racefix:
fsmonitor: update documentation for hook version and watchman hooks
fsmonitor: add fsmonitor hook scripts for version 2
fsmonitor: handle version 2 of the hooks that will use opaque token
fsmonitor: change last update timestamp on the index_state to opaque token
Traditionally, we avoided threaded grep while searching in objects
(as opposed to files in the working tree) as accesses to the object
layer is not thread-safe. This limitation is getting lifted.
* mt/threaded-grep-in-object-store:
grep: use no. of cores as the default no. of threads
grep: move driver pre-load out of critical section
grep: re-enable threads in non-worktree case
grep: protect packed_git [re-]initialization
grep: allow submodule functions to run in parallel
submodule-config: add skip_if_read option to repo_read_gitmodules()
grep: replace grep_read_mutex by internal obj read lock
object-store: allow threaded access to object reading
replace-object: make replace operations thread-safe
grep: fix racy calls in grep_objects()
grep: fix race conditions at grep_submodule()
grep: fix race conditions on userdiff calls
The transport protocol version 2 becomes the default one.
* jn/promote-proto2-to-default:
fetch: default to protocol version 2
protocol test: let protocol.version override GIT_TEST_PROTOCOL_VERSION
test: request GIT_TEST_PROTOCOL_VERSION=0 when appropriate
config doc: protocol.version is not experimental
fetch test: use more robust test for filtered objects
Two help messages given when "git add" notices the user gave it
nothing to add have been updated to use advise() API.
* hw/advice-add-nothing:
add: change advice config variables used by the add API
add: use advise function to display hints
Technical details of the bundle format has been documented.
I think this is in a good enough shape.
* ms/doc-bundle-format:
doc: describe Git bundle format
"git grep --no-index" should not get affected by the contents of
the .gitmodules file but when "--recurse-submodules" is given or
the "submodule.recurse" variable is set, it did. Now these
settings are ignored in the "--no-index" mode.
* pb/do-not-recurse-grep-no-index:
grep: ignore --recurse-submodules if --no-index is given
Corner case bugs in "git clean" that stems from a (necessarily for
performance reasons) awkward calling convention in the directory
enumeration API has been corrected.
* en/fill-directory-fixes-more:
dir: point treat_leading_path() warning to the right place
dir: restructure in a way to avoid passing around a struct dirent
dir: treat_leading_path() and read_directory_recursive(), round 2
clean: demonstrate a bug with pathspecs
Clarify documentation on committer/author identities.
* bc/author-committer-doc:
doc: provide guidance on user.name format
docs: expand on possible and recommended user config options
doc: move author and committer information to git-commit(1)
Work around test breakages caused by custom regex engine used in
libasan, when address sanitizer is used with more recent versions
of gcc and clang.
* jk/asan-build-fix:
Makefile: use compat regex with SANITIZE=address
The code recently added in this release to move to the entry beyond
the ones in the same directory in the index in the sparse-cone mode
did not count the number of entries to skip over incorrectly, which
has been corrected.
* ds/sparse-cone:
.mailmap: fix GGG authoship screwup
unpack-trees: correctly compute result count
"git restore --staged" did not correctly update the cache-tree
structure, resulting in bogus trees to be written afterwards, which
has been corrected.
* nd/switch-and-restore:
restore: invalidate cache-tree when removing entries with --staged
Reduce unnecessary round-trip when running "ls-remote" over the
stateless RPC mechanism.
* jk/no-flush-upon-disconnecting-slrpc-transport:
transport: don't flush when disconnecting stateless-rpc helper
Complete an update to tutorial that encourages "git switch" over
"git checkout" that was done only half-way.
* hw/tutorial-favor-switch-over-checkout:
doc/gitcore-tutorial: fix prose to match example command
The code that tries to skip over the entries for the paths in a
single directory using the cache-tree was not careful enough
against corrupt index file.
* es/unpack-trees-oob-fix:
unpack-trees: watch for out-of-range index position
