The t1092-sparse-checkout-compatibility.sh tests compare the stdout and
stderr for several Git commands across both full checkouts, sparse
checkouts with a full index, and sparse checkouts with a sparse index.
Since these are direct comparisons, sometimes a progress indicator can
flush at unpredictable points, especially on slower machines. This
causes the tests to be flaky.
One standard way to avoid this is to add GIT_PROGRESS_DELAY=0 to the Git
commands that are run, as this will force every progress indicator
created with start_progress_delay() to be created immediately. However,
there are some progress indicators that are created in the case of a
full index that are not created with a sparse index. Moreover, their
values may be different as those indexes have a different number of
entries.
Instead, use GIT_PROGRESS_DELAY=-1 (which will turn into UINT_MAX)
to ensure that any reasonable machine running these tests would
never display delayed progress indicators.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We used to read the init.templateDir setting at builtin/init-db.c using
a git_config() callback that, in turn, called git_config_pathname(). To
simplify the config reading logic at this file and plug a memory leak,
this was replaced by a direct call to git_config_get_value() at
e4de4502e6 ("init: remove git_init_db_config() while fixing leaks",
2021-03-14). However, this function doesn't provide path expanding
semantics, like git_config_pathname() does, so paths with '~/' and
'~user/' are treated literally. This makes 'git init' fail to handle
init.templateDir paths using these constructs:
$ git config init.templateDir '~/templates_dir'
$ git init
'warning: templates not found in ~/templates_dir'
Replace the git_config_get_value() call by git_config_get_pathname(),
which does the '~/' and '~user/' expansions. Also add a regression test.
Note that unlike git_config_get_value(), the config cache does not own
the memory for the path returned by git_config_get_pathname(), so we
must free() it.
Reported on IRC by rkta.
Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix a regression with the "the editor exited uncleanly, aborting
everything" error message going missing after my
d21616c039 (git-send-email: refactor duplicate $? checks into a
function, 2021-04-06).
I introduced a $msg variable, but did not actually use it. This caused
us to miss the optional error message supplied by the "do_edit"
codepath. Fix that, and add tests to check that this works.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git for Windows is a native Windows program that works with native
absolute paths in the drive letter style C:\dir. The auxiliary
infrastructure is based on MSYS2, which uses POSIX style /C/dir.
When we test for output of absolute paths produced by git.exe, we
usally have to expect C:\dir style paths. To produce such expected
paths, we have to use $(pwd) in the test scripts; the alternative,
$PWD, produces a POSIX style path. ($PWD is a shell variable, and the
shell is bash, an MSYS2 program, and operates in the POSIX realm.)
There are two recently added tests that were written to expect C:\dir
paths. The output that is tested is produced by `git send-email`, but
behind the scenes, this is a Perl script, which also works in the
POSIX realm and produces /C/dir style output.
In the first test case that is changed here, replace $(pwd) by $PWD
so that the expected path is constructed using /C/dir style.
The second test case sets core.hooksPath to an absolute path. Since
the test script talks to native git.exe, it is supposed to place a
C:/dir style path into the configuration; therefore, keep $(pwd).
When this configuration value is consumed by the Perl script, it is
transformed to /C/dir style by the MSYS2 layer and echoed back in
this form in the error message. Hence, do use $PWD for the expected
value.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix the 'uploadpack.blobPackfileUri' description in packfile-uri.txt
and the correct format also can be seen in t5702.
Signed-off-by: Teng Long <dyroneteng@gmail.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently GNU make already removes files when catching an interruption
signal, however, in order to deal with other kinds of errors a
workaround is in place to store target output to a temporary file, and
only move it to its right place on success.
By enabling the built-in .DELETE_ON_ERROR we let make do this task, so
we don't have to.
This way the rules can be simplified a lot.
Suggested-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commits 50cff52f1a (When generating manpages, delete outdated targets
first., 2007-08-02) and f9286765b2 (Documentation/Makefile: remove
cmd-list.made before redirecting to it., 2007-08-06) created these rm
instances for a very rare corner-case: building as root by mistake.
It's odd to have workarounds here, but nowhere else in the Makefile--
which already fails in this stuation, starting from
Documentation/technical/.
We gain nothing but complexity, so let's remove them.
Comments-by: Jeff King <peff@peff.net>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
asciidoc needs asciidoc.conf, asciidoctor asciidoctor-extensions.rb.
Neither needs the other.
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Another brown paper bag inconsistency fix for a new feature
introduced during this cycle.
* dl/stash-show-untracked-fixup:
stash show: use stash.showIncludeUntracked even when diff options given
The "simple-ipc" did not compile without pthreads support, but the
build procedure was not properly account for it.
* jh/simple-ipc-sans-pthread:
simple-ipc: correct ifdefs when NO_PTHREADS is defined
The "rev-parse" command did not diagnose the lack of argument to
"--path-format" option, which was introduced in v2.31 era, which
has been corrected.
* wm/rev-parse-path-format-wo-arg:
rev-parse: fix segfault with missing --path-format argument
Despite that tar is available everywhere, it's not required by POSIX.
In our build system, users are allowed to specify which tar to be used
in Makefile knobs. Furthermore, GNU tar (gtar) is prefered when autotools
is being used.
In our testsuite, 7 out of 9 tar-required-tests use "$TAR", the other
two use "tar".
Let's change the remaining two tests to "$TAR".
Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If options pertaining to how the diff is displayed is provided to
`git stash show`, the command will ignore the stash.showIncludeUntracked
configuration variable, defaulting to not showing any untracked files.
This is unintuitive behaviour since the format of the diff output and
whether or not to display untracked files are orthogonal.
Use stash.showIncludeUntracked even when diff options are given. Of
course, this is still overridable via the command-line options.
Update the documentation to explicitly say which configuration variables
will be overridden when a diff options are given.
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix long standing inconsistency between -c/--cc that do imply -p on
one side, and -m that did not imply -p on the other side.
Change corresponding test accordingly, as "log -m" output should now
match one from "log -m -p", rather than from just "log".
Change documentation accordingly.
NOTES:
After this patch
git log -m
produces diffs without need to provide -p as well, that improves both
consistency and usability. It gets even more useful if one sets
"log.diffMerges" configuration variable to "first-parent" to force -m
produce usual diff with respect to first parent only.
This patch, however, does not change behavior when specific diff
format is explicitly provided on the command-line, so that commands
like
git log -m --raw
git log -m --stat
are not affected, nor does it change commands where specific diff
format is active by default, such as:
git diff-tree -m
It's also worth to be noticed that exact historical semantics of -m is
still provided by --diff-merges=separate.
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is refactoring change in preparation for the next commit that
will let -m imply -p.
The old name doesn't match the intention to let not only -c/-cc imply
-p, but also -m, that is not a "combined" format, so we rename the
flag accordingly.
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Passing "-m" in "git log --first-parent -m" is not needed as
--first-parent implies --diff-merges=first-parent anyway. OTOH, it
will stop being harmless once we let "-m" imply "-p".
While we are at it, fix corresponding test description in t3903-stash
to match what it actually tests.
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
rev-list doesn't utilize -m. It happens to eat it silently, so this
bug went unnoticed.
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Move specific handling of "-m" for diff-index to diff-index.c, so
diff-merges is left to handle only diff for merges options.
Being a better design by itself, this is especially essential in
preparation for letting -m imply -p, as "diff-index -m" obviously
should not imply -p, as it's entirely unrelated.
To handle this, in addition to moving specific diff-index "-m" code
out of diff-merges, we introduce new
diff_merges_suppress_options_parsing()
and call it before generic options processing in cmd_diff_index().
This new diff_merges_suppress_options_parsing() could then be reused
and called before invocations of setup_revisions() for other commands
that don't need --diff-merges options, but that's outside of the scope
of these patch series.
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
-m in "git diff-index" means "match missing", that differs
from its meaning in "git diff". Let's check it in diff-index.
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We want to ensure we don't affect plumbing commands with our changes
of "-m" semantics, so add corresponding test.
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is to ensure we won't break different diff formats when we start
to imply "-p" by "-m".
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is to ensure we won't break different diff formats when we start
to imply "-p" by "-m".
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is to notice current behavior that we are going to change when we
start to imply "-p" by "-m".
Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Simple IPC always requires threads (in addition to various
platform-specific IPC support). Fix the ifdefs in the Makefile
to define SUPPORTS_SIMPLE_IPC when appropriate.
Previously, the Unix version of the code would only verify that
Unix domain sockets were available.
This problem was reported here:
https://lore.kernel.org/git/YKN5lXs4AoK%2FJFTO@coredump.intra.peff.net/T/#m08be8f1942ea8a2c36cfee0e51cdf06489fdeafc
Reported-by: Randall S. Becker <rsbecker@nexbridge.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Classic string concatenation while forgetting a space character.
Signed-off-by: Jean-Noël Avila <jn.avila@free.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Refactor tr2_dst_try_uds_connect() to avoid a gcc warning[1] that
appears under -O3 (but not -O2). This makes the build pass under
DEVELOPER=1 without needing a DEVOPTS=no-error.
This can be reproduced with GCC Debian 8.3.0-6, but not e.g. with
clang 7.0.1-8+deb10u2. We've had this warning since
ee4512ed48 (trace2: create new combined trace facility, 2019-02-22).
As noted in [2] this warning happens because the compiler doesn't
assume that errno must be non-zero after a failed syscall.
Let's work around by using the well-established "saved_errno" pattern,
along with returning -1 ourselves instead of "errno". The caller can
thus rely on our "errno" on failure.
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61846 for a related
bug report against GCC.
1.
trace2/tr2_dst.c: In function ‘tr2_dst_get_trace_fd.part.5’:
trace2/tr2_dst.c:296:10: warning: ‘fd’ may be used uninitialized in this function [-Wmaybe-uninitialized]
dst->fd = fd;
~~~~~~~~^~~~
trace2/tr2_dst.c:229:6: note: ‘fd’ was declared here
int fd;
^~
2. https://lore.kernel.org/git/20200404142131.GA679473@coredump.intra.peff.net/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Regression fix for a change made during this cycle.
* cs/http-use-basic-after-failed-negotiate:
Revert "remote-curl: fall back to basic auth if Negotiate fails"
t5551: test http interaction with credential helpers
When there are many renames between the old base of a series of commits
and the new base, the way sequencer.c, merge-recursive.c, and
diffcore-rename.c have traditionally split the work resulted in
redetecting the same renames with each and every commit being
transplanted. To address this, the last several commits have been
creating a cache of rename detection results, determining when it was
safe to use such a cache in subsequent merge operations, adding helper
functions, and so on. See the previous half dozen commit messages for
additional discussion of this optimization, particularly the message a
few commits ago entitled "add code to check for whether cached renames
can be reused". This commit finally ties all of that work together,
modifying the merge algorithm to make use of these cached renames.
For the testcases mentioned in commit 557ac0350d ("merge-ort: begin
performance work; instrument with trace2_region_* calls", 2020-10-28),
this change improves the performance as follows:
Before After
no-renames: 5.665 s ± 0.129 s 5.622 s ± 0.059 s
mega-renames: 11.435 s ± 0.158 s 10.127 s ± 0.073 s
just-one-mega: 494.2 ms ± 6.1 ms 500.3 ms ± 3.8 ms
That's a fairly small improvement, but mostly because the previous
optimizations were so effective for these particular testcases; this
optimization only kicks in when the others don't. If we undid the
basename-guided rename detection and skip-irrelevant-renames
optimizations, then we'd see that this series by itself improved
performance as follows:
Before Basename Series After Just This Series
no-renames: 13.815 s ± 0.062 s 5.697 s ± 0.080 s
mega-renames: 1799.937 s ± 0.493 s 205.709 s ± 0.457 s
Since this optimization kicks in to help accelerate cases where the
previous optimizations do not apply, this last comparison shows that
this cached-renames optimization has the potential to help signficantly
in cases that don't meet the requirements for the other optimizations to
be effective.
The changes made in this optimization also lay some important groundwork
for a future optimization around having collect_merge_info() avoid
recursing into subtrees in more cases.
However, for this optimization to be effective, merge_switch_to_result()
should only be called when the rebase or cherry-pick operation has
either completed or hit a case where the user needs to resolve a
conflict or edit the result. If it is called after every commit, as
sequencer.c does, then the working tree and index are needlessly updated
with every commit and the cached metadata is tossed, defeating this
optimization. Refactoring sequencer.c to only call
merge_switch_to_result() at the end of the operation is a bigger
undertaking, and the practical benefits of this optimization will not be
realized until that work is performed. Since `test-tool fast-rebase`
only updates at the end of the operation, it was used to obtain the
timings above.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As documented in Documentation/technical/remembering-renames.txt, and as
tested for in the two testcases in t6429 with "rename same file
identically" in their description, there is one case where we need to
have renames in one commit NOT be cached for the next commit in our
rebase sequence -- namely, rename/rename(1to1) cases. Rather than
specifically trying to uncache those and fix up dir_rename_counts() to
match (which would also be valid but more work), we simply disable the
optimization when this really rare type of rename occurs.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If we have a usable rename cache, then we can remove from
relevant_sources all the paths that were cached;
diffcore_rename_extended() can then consider an even smaller set of
relevant_sources in its rename detection.
However, when diffcore_rename_extended() is done, we will need to take
the renames it detected and then add back in all the ones we had cached
from before.
Add helper functions for doing these two operations; the next commit
will make use of them.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Previous commits created an in-memory cache of the results of rename
detection, and added logic to detect when that cache could appropriately
be used in a subsequent merge operation -- but we were still
unconditionally clearing the cache with each new merge operation anyway.
If it is valid to reuse the cache from one of the two sides of history,
preserve that side.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Previously, callers of the merge-ort API could have passed an
uninitialized value for struct merge_result *result. However, we want
to check result to see if it has cached renames from a previous merge
that we can reuse; such values would be found behind result->priv.
However, if result->priv is uninitialized, attempting to access behind
it will give a segfault. So, we need result->priv to be NULL (which
will be the case if the caller does a memset(&result, 0)), or be written
by a previous call to the merge-ort machinery. Documenting this
requirement may help, but despite being the person who introduced this
requirement, I still missed it once and it did not fail in a very clear
way and led to a long debugging session.
Add a _properly_initialized field to merge_result; that value will be
0 if the caller zero'ed the merge_result, it will be set to a very
specific value by a previous run by the merge-ort machinery, and if it's
uninitialized it will most likely either be 0 or some value that does
not match the specific one we'd expect allowing us to throw a much more
meaningful error.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We need to know when renames detected in a previous merge operation can
be reused in a later merge operation. Consider the following setup
(from the git-rebase manpage):
A---B---C topic
/
D---E---F---G master
After rebasing, this will appear as:
A'--B'--C' topic
/
D---E---F---G master
Further, let's say that 'oldfile' was renamed to 'newfile' between E
and G. The rebase or cherry-pick of A onto G will involve a three-way
merge between E (as the merge base) and G and A. After detecting the
rename between E:oldfile and G:newfile, there will be a three-way
content merge of the following:
E:oldfile
G:newfile
A:oldfile
and produce a new result:
A':newfile
Now, when we want to pick B onto A', we will need to do a three-way
merge between A (as the merge-base) and A' and B. This will involve
a three-way content merge of
A:oldfile
A':newfile
B:oldfile
but only if we can detect that A:oldfile is similar enough to A':newfile
to be used together in a three-way content merge, i.e. only if we can
detect that A:oldfile and A':newfile are a rename. But we already know
that A:oldfile and A':newfile are similar enough to be used in a
three-way content merge, because that is precisely where A':newfile came
from in the previous merge.
Note that A & A' both appear in both merges. That gives us the
condition under which we can reuse renames.
There are a couple important points about this optimization:
- If the rebase or cherry-pick halts for user conflicts, these caches
are NOT saved anywhere. Thus, resuming a halted rebase or
cherry-pick will result in no reused renames for the next commit.
This is intentional, as user resolution can change files
significantly and in ways that violate the similarity assumptions
here.
- Technically, in a *very* narrow case this might give slightly
different results for rename detection. Using the example above,
if:
* E:oldfile had 20 lines
* G:newfile added 10 new lines at the beginning of the file
* A:oldfile deleted all but the first three lines of the file
then
=> A':newfile would have 13 lines, 3 of which matches those
in A:oldfile.
Consider the two cases:
* Without this optimization:
- the next step of the rebase operation (moving B to B')
would not detect the rename betwen A:oldfile and A':newfile
- we'd thus get a modify/delete conflict with the rebase
operation halting for the user to resolve, and have both
A':newfile and B:oldfile sitting in the working tree.
* With this optimization:
- the rename between A:oldfile and A':newfile would be detected
via the cache of renames
- a three-way merge between A:oldfile, A':newfile, and B:oldfile
would commence and be written to A':newfile
Now, is the difference in behavior a bug...or a bugfix? I can't
tell. Given that A:oldfile and A':newfile are not very similar,
when we three-way merge with B:oldfile it seems likely we'll hit a
conflict for the user to resolve. And it shouldn't be too hard for
users to see why we did that three-way merge; oldfile and newfile
*were* renames somewhere in the sequence. So, most of these corner
cases will still behave similarly -- namely, a conflict given to the
user to resolve. Also, consider the interesting case when commit B
is a clean revert of commit A. Without this optimization, a rebase
could not both apply a weird patch like A and then immediately
revert it; users would be forced to resolve merge conflicts. With
this optimization, it would successfully apply the clean revert.
So, there is certainly at least one case that behaves better. Even
if it's considered a "difference in behavior", I think both behaviors
are reasonable, and the time savings provided by this optimization
justify using the slightly altered rename heuristics.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fill in cache_pairs, cached_target_names, and cached_irrelevant based on
rename detection results. Future commits will make use of these values.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When there are many renames between the old base of a series of commits
and the new base for a series of commits, the sequence of merges
employed to transplant those commits (from a cherry-pick or rebase
operation) will repeatedly detect the exact same renames. This is
wasted effort.
Add data structures which will be used to cache rename detection
results, along with the initialization and deallocation of these data
structures. Future commits will populate these caches, detect the
appropriate circumstances when they can be used, and employ them to
avoid re-detecting the same renames repeatedly.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We will soon be adding an optimization that caches (in memory only,
never written to disk) upstream renames during a sequence of merges such
as occurs during a cherry-pick or rebase operation. Add several tests
meant to stress such an implementation to ensure it does the right
thing, and include a test whose outcome we will later change due to this
optimization as well.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Previously, when fast-rebase hit a conflict, it simply aborted and left
HEAD, the index, and the working tree where they were before the
operation started. While fast-rebase does not support restarting from a
conflicted state, write the conflicted state out anyway as it gives us a
way to see what the conflicts are and write tests that check for them.
This will be important in the upcoming commits, because sequencer.c is
only superficially integrated with merge-ort.c; in particular, it calls
merge_switch_to_result() after EACH merge instead of only calling it at
the end of all the sequence of merges (or when a conflict is hit). This
not only causes needless updates to the working copy and index, but also
causes all intermediate data to be freed and tossed, preventing caching
information from one merge to the next. However, integrating
sequencer.c more deeply with merge-ort.c is a big task, and making this
small extension to fast-rebase.c provides us with a simple way to test
the edge and corner cases that we want to make sure continue working.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
assert() can succinctly document expectations for the code, and do so in
a way that may be useful to future folks trying to refactor the code and
change basic assumptions; it allows them to more quickly find some
places where their violations of previous assumptions trips things up.
Unfortunately, assert() can surround a function call with important
side-effects, which is a huge mistake since some users will compile with
assertions disabled. I've had to debug such mistakes before in other
codebases, so I should know better. Luckily, this was only in test
code, but it's still very embarrassing. Change an assert() to an if
(...) BUG (...).
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Remembering renames on the upstream side of history in an early merge of
a rebase or cherry-pick for re-use in a latter merge of the same
operation makes pretty good intuitive sense. However, trying to show
that it doesn't cause some subtle behavioral difference or some funny
edge or corner case is much more involved. And, in fact, it does
introduce a subtle behavioral change.
Document all the assumptions, special cases, and logic involved in such
an optimization, and describe why this optimization is safe under the
current optimizations/features/etc. -- even when the subtle behavioral
change is triggered.
Part of the point of adding this document that goes over the
optimization in such laborious detail, is that it is possible that
significant future changes (optimizations or feature changes) could
interact with this optimization in interesting ways; this document is
here to help folks making big changes sanity check that the assumptions
and arguments underlying this optimization are still valid. (As a side
note, creating this document forced me to review things in sufficient
detail that I found I was not properly caching directory-rename-induced
renames, resulting in the code not being aware of those renames and
causing unnecessary diffcore_rename_extended() calls in subsequent
merges.)
A subsequent commit will add several testcases based on this document
meant to stress-test the implementation and also document the case with
the subtle behavioral change.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
