A common mistake when writing binary search is to allow possible
integer overflow by using the simple average:
mid = (min + max) / 2;
Instead, use the overflow-safe version:
mid = min + (max - min) / 2;
This translation is safe since the operation occurs inside a loop
conditioned on "min < max". The included changes were found using
the following git grep:
git grep '/ *2;' '*.c'
Making this cleanup will prevent future review friction when a new
binary search is contructed based on existing code.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When adding a new function to the end of a file, it's enough to know
that 1) the addition is at the end of the file; and 2) there is a
function _somewhere_ in there.
If we had simply been changing the end of an existing function, then we
would also be deleting something from the old version.
This fixes the case where we add e.g.
// Begin of dummy
static int dummy(void)
{
}
to the end of the file.
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git diff" and its family had two experimental heuristics to shift
the contents of a hunk to make the patch easier to read. One of
them turns out to be better than the other, so leave only the
"--indent-heuristic" option and remove the other one.
* jc/retire-compaction-heuristics:
diff: retire "compaction" heuristics
When a patch inserts a block of lines, whose last lines are the
same as the existing lines that appear before the inserted block,
"git diff" can choose any place between these existing lines as the
boundary between the pre-context and the added lines (adjusting the
end of the inserted block as appropriate) to come up with variants
of the same patch, and some variants are easier to read than others.
We have been trying to improve the choice of this boundary, and Git
2.11 shipped with an experimental "compaction-heuristic". Since
then another attempt to improve the logic further resulted in a new
"indent-heuristic" logic. It is agreed that the latter gives better
result overall, and the former outlived its usefulness.
Retire "compaction", and keep "indent" as an experimental feature.
The latter hopefully will be turned on by default in a future
release, but that should be done as a separate step.
Suggested-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The xdiff code hashes every line of both sides of a diff,
and then compares those hashes to find duplicates. The
overall performance depends both on how fast we can compute
the hashes, but also on how many hash collisions we see.
The idea of XDL_FAST_HASH is to speed up the hash
computation. But the generated hashes have worse collision
behavior. This means that in some cases it speeds diffs up
(running "git log -p" on git.git improves by ~8% with it),
but in others it can slow things down. One pathological case
saw over a 100x slowdown[1].
There may be a better hash function that covers both
properties, but in the meantime we are better off with the
original hash. It's slightly slower in the common case, but
it has fewer surprising pathological cases.
[1] http://public-inbox.org/git/20141222041944.GA441@peff.net/
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit e8adf23 (xdl_change_compact(): introduce the concept
of a change group, 2016-08-22) added a "struct group" type
to xdiff/xdiffi.c. But the POSIX system header "grp.h"
already defines "struct group" (it is part of the getgrnam
interface). This happens to work because the new type is
local to xdiffi.c, and the xdiff code includes a relatively
small set of system headers. But it will break compilation
if xdiff ever switches to using git-compat-util.h. It can
also probably cause confusion with tools that look at the
whole code base, like coccinelle or ctags.
Let's resolve by giving the xdiff variant a scoped name,
which is closer to other xdiff types anyway (e.g.,
xdlfile_t, though note that xdiff is fond if typedefs when
Git usually is not).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Output from "git diff" can be made easier to read by selecting
which lines are common and which lines are added/deleted
intelligently when the lines before and after the changed section
are the same. A command line option is added to help with the
experiment to find a good heuristics.
* mh/diff-indent-heuristic:
blame: honor the diff heuristic options and config
parse-options: add parse_opt_unknown_cb()
diff: improve positioning of add/delete blocks in diffs
xdl_change_compact(): introduce the concept of a change group
recs_match(): take two xrecord_t pointers as arguments
is_blank_line(): take a single xrecord_t as argument
xdl_change_compact(): only use heuristic if group can't be matched
xdl_change_compact(): fix compaction heuristic to adjust ixo
"git diff -W" output needs to extend the context backward to
include the header line of the current function and also forward to
include the body of the entire current function up to the header
line of the next one. This process may have to merge to adjacent
hunks, but the code forgot to do so in some cases.
* rs/xdiff-merge-overlapping-hunks-for-W-context:
xdiff: fix merging of hunks with -W context and -u context
Some groups of added/deleted lines in diffs can be slid up or down,
because lines at the edges of the group are not unique. Picking good
shifts for such groups is not a matter of correctness but definitely has
a big effect on aesthetics. For example, consider the following two
diffs. The first is what standard Git emits:
--- a/9c572b21dd090a1e5c5bb397053bf8043ffe7fb4:git-send-email.perl
+++ b/6dcfa306f2b67b733a7eb2d7ded1bc9987809edb:git-send-email.perl
@@ -231,6 +231,9 @@ if (!defined $initial_reply_to && $prompting) {
}
if (!$smtp_server) {
+ $smtp_server = $repo->config('sendemail.smtpserver');
+}
+if (!$smtp_server) {
foreach (qw( /usr/sbin/sendmail /usr/lib/sendmail )) {
if (-x $_) {
$smtp_server = $_;
The following diff is equivalent, but is obviously preferable from an
aesthetic point of view:
--- a/9c572b21dd090a1e5c5bb397053bf8043ffe7fb4:git-send-email.perl
+++ b/6dcfa306f2b67b733a7eb2d7ded1bc9987809edb:git-send-email.perl
@@ -230,6 +230,9 @@ if (!defined $initial_reply_to && $prompting) {
$initial_reply_to =~ s/(^\s+|\s+$)//g;
}
+if (!$smtp_server) {
+ $smtp_server = $repo->config('sendemail.smtpserver');
+}
if (!$smtp_server) {
foreach (qw( /usr/sbin/sendmail /usr/lib/sendmail )) {
if (-x $_) {
This patch teaches Git to pick better positions for such "diff sliders"
using heuristics that take the positions of nearby blank lines and the
indentation of nearby lines into account.
The existing Git code basically always shifts such "sliders" as far down
in the file as possible. The only exception is when the slider can be
aligned with a group of changed lines in the other file, in which case
Git favors depicting the change as one add+delete block rather than one
add and a slightly offset delete block. This naive algorithm often
yields ugly diffs.
Commit d634d61ed6 improved the situation somewhat by preferring to
position add/delete groups to make their last line a blank line, when
that is possible. This heuristic does more good than harm, but (1) it
can only help if there are blank lines in the right places, and (2)
always picks the last blank line, even if there are others that might be
better. The end result is that it makes perhaps 1/3 as many errors as
the default Git algorithm, but that still leaves a lot of ugly diffs.
This commit implements a new and much better heuristic for picking
optimal "slider" positions using the following approach: First observe
that each hypothetical positioning of a diff slider introduces two
splits: one between the context lines preceding the group and the first
added/deleted line, and the other between the last added/deleted line
and the first line of context following it. It tries to find the
positioning that creates the least bad splits.
Splits are evaluated based only on the presence and locations of nearby
blank lines, and the indentation of lines near the split. Basically, it
prefers to introduce splits adjacent to blank lines, between lines that
are indented less, and between lines with the same level of indentation.
In more detail:
1. It measures the following characteristics of a proposed splitting
position in a `struct split_measurement`:
* the number of blank lines above the proposed split
* whether the line directly after the split is blank
* the number of blank lines following that line
* the indentation of the nearest non-blank line above the split
* the indentation of the line directly below the split
* the indentation of the nearest non-blank line after that line
2. It combines the measured attributes using a bunch of
empirically-optimized weighting factors to derive a `struct
split_score` that measures the "badness" of splitting the text at
that position.
3. It combines the `split_score` for the top and the bottom of the
slider at each of its possible positions, and selects the position
that has the best `split_score`.
I determined the initial set of weighting factors by collecting a corpus
of Git histories from 29 open-source software projects in various
programming languages. I generated many diffs from this corpus, and
determined the best positioning "by eye" for about 6600 diff sliders. I
used about half of the repositories in the corpus (corresponding to
about 2/3 of the sliders) as a training set, and optimized the weights
against this corpus using a crude automated search of the parameter
space to get the best agreement with the manually-determined values.
Then I tested the resulting heuristic against the full corpus. The
results are summarized in the following table, in column `indent-1`:
| repository | count | Git 2.9.0 | compaction | compaction-fixed | indent-1 | indent-2 |
| --------------------- | ----- | -------------- | -------------- | ---------------- | -------------- | -------------- |
| afnetworking | 109 | 89 (81.7%) | 37 (33.9%) | 37 (33.9%) | 2 (1.8%) | 2 (1.8%) |
| alamofire | 30 | 18 (60.0%) | 14 (46.7%) | 15 (50.0%) | 0 (0.0%) | 0 (0.0%) |
| angular | 184 | 127 (69.0%) | 39 (21.2%) | 23 (12.5%) | 5 (2.7%) | 5 (2.7%) |
| animate | 313 | 2 (0.6%) | 2 (0.6%) | 2 (0.6%) | 2 (0.6%) | 2 (0.6%) |
| ant | 380 | 356 (93.7%) | 152 (40.0%) | 148 (38.9%) | 15 (3.9%) | 15 (3.9%) | *
| bugzilla | 306 | 263 (85.9%) | 109 (35.6%) | 99 (32.4%) | 14 (4.6%) | 15 (4.9%) | *
| corefx | 126 | 91 (72.2%) | 22 (17.5%) | 21 (16.7%) | 6 (4.8%) | 6 (4.8%) |
| couchdb | 78 | 44 (56.4%) | 26 (33.3%) | 28 (35.9%) | 6 (7.7%) | 6 (7.7%) | *
| cpython | 937 | 158 (16.9%) | 50 (5.3%) | 49 (5.2%) | 5 (0.5%) | 5 (0.5%) | *
| discourse | 160 | 95 (59.4%) | 42 (26.2%) | 36 (22.5%) | 18 (11.2%) | 13 (8.1%) |
| docker | 307 | 194 (63.2%) | 198 (64.5%) | 253 (82.4%) | 8 (2.6%) | 8 (2.6%) | *
| electron | 163 | 132 (81.0%) | 38 (23.3%) | 39 (23.9%) | 6 (3.7%) | 6 (3.7%) |
| git | 536 | 470 (87.7%) | 73 (13.6%) | 78 (14.6%) | 16 (3.0%) | 16 (3.0%) | *
| gitflow | 127 | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
| ionic | 133 | 89 (66.9%) | 29 (21.8%) | 38 (28.6%) | 1 (0.8%) | 1 (0.8%) |
| ipython | 482 | 362 (75.1%) | 167 (34.6%) | 169 (35.1%) | 11 (2.3%) | 11 (2.3%) | *
| junit | 161 | 147 (91.3%) | 67 (41.6%) | 66 (41.0%) | 1 (0.6%) | 1 (0.6%) | *
| lighttable | 15 | 5 (33.3%) | 0 (0.0%) | 2 (13.3%) | 0 (0.0%) | 0 (0.0%) |
| magit | 88 | 75 (85.2%) | 11 (12.5%) | 9 (10.2%) | 1 (1.1%) | 0 (0.0%) |
| neural-style | 28 | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) |
| nodejs | 781 | 649 (83.1%) | 118 (15.1%) | 111 (14.2%) | 4 (0.5%) | 5 (0.6%) | *
| phpmyadmin | 491 | 481 (98.0%) | 75 (15.3%) | 48 (9.8%) | 2 (0.4%) | 2 (0.4%) | *
| react-native | 168 | 130 (77.4%) | 79 (47.0%) | 81 (48.2%) | 0 (0.0%) | 0 (0.0%) |
| rust | 171 | 128 (74.9%) | 30 (17.5%) | 27 (15.8%) | 16 (9.4%) | 14 (8.2%) |
| spark | 186 | 149 (80.1%) | 52 (28.0%) | 52 (28.0%) | 2 (1.1%) | 2 (1.1%) |
| tensorflow | 115 | 66 (57.4%) | 48 (41.7%) | 48 (41.7%) | 5 (4.3%) | 5 (4.3%) |
| test-more | 19 | 15 (78.9%) | 2 (10.5%) | 2 (10.5%) | 1 (5.3%) | 1 (5.3%) | *
| test-unit | 51 | 34 (66.7%) | 14 (27.5%) | 8 (15.7%) | 2 (3.9%) | 2 (3.9%) | *
| xmonad | 23 | 22 (95.7%) | 2 (8.7%) | 2 (8.7%) | 1 (4.3%) | 1 (4.3%) | *
| --------------------- | ----- | -------------- | -------------- | ---------------- | -------------- | -------------- |
| totals | 6668 | 4391 (65.9%) | 1496 (22.4%) | 1491 (22.4%) | 150 (2.2%) | 144 (2.2%) |
| totals (training set) | 4552 | 3195 (70.2%) | 1053 (23.1%) | 1061 (23.3%) | 86 (1.9%) | 88 (1.9%) |
| totals (test set) | 2116 | 1196 (56.5%) | 443 (20.9%) | 430 (20.3%) | 64 (3.0%) | 56 (2.6%) |
In this table, the numbers are the count and percentage of human-rated
sliders that the corresponding algorithm got *wrong*. The columns are
* "repository" - the name of the repository used. I used the diffs
between successive non-merge commits on the HEAD branch of the
corresponding repository.
* "count" - the number of sliders that were human-rated. I chose most,
but not all, sliders to rate from those among which the various
algorithms gave different answers.
* "Git 2.9.0" - the default algorithm used by `git diff` in Git 2.9.0.
* "compaction" - the heuristic used by `git diff --compaction-heuristic`
in Git 2.9.0.
* "compaction-fixed" - the heuristic used by `git diff
--compaction-heuristic` after the fixes from earlier in this patch
series. Note that the results are not dramatically different than
those for "compaction". Both produce non-ideal diffs only about 1/3 as
often as the default `git diff`.
* "indent-1" - the new `--indent-heuristic` algorithm, using the first
set of weighting factors, determined as described above.
* "indent-2" - the new `--indent-heuristic` algorithm, using the final
set of weighting factors, determined as described below.
* `*` - indicates that repo was part of training set used to determine
the first set of weighting factors.
The fact that the heuristic performed nearly as well on the test set as
on the training set in column "indent-1" is a good indication that the
heuristic was not over-trained. Given that fact, I ran a second round of
optimization, using the entire corpus as the training set. The resulting
set of weights gave the results in column "indent-2". These are the
weights included in this patch.
The final result gives consistently and significantly better results
across the whole corpus than either `git diff` or `git diff
--compaction-heuristic`. It makes only about 1/30 as many errors as the
former and about 1/10 as many errors as the latter. (And a good fraction
of the remaining errors are for diffs that involve weirdly-formatted
code, sometimes apparently machine-generated.)
The tools that were used to do this optimization and analysis, along
with the human-generated data values, are recorded in a separate project
[1].
This patch adds a new command-line option `--indent-heuristic`, and a
new configuration setting `diff.indentHeuristic`, that activate this
heuristic. This interface is only meant for testing purposes, and should
be finalized before including this change in any release.
[1] https://github.com/mhagger/diff-slider-tools
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If the function context for a hunk (with -W) reaches the beginning of
the next hunk then we need to merge these two -- otherwise we'd show
some lines twice, which looks strange and even confuses git apply. We
already do this checking and merging in xdl_emit_diff(), but forget to
consider regular context (with -u or -U).
Fix that by merging hunks already if function context of the first one
touches or overlaps regular context of the second one.
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The idea of xdl_change_compact() is fairly simple:
* Proceed through groups of changed lines in the file to be compacted,
keeping track of the corresponding location in the "other" file.
* If possible, slide the group up and down to try to give the most
aesthetically pleasing diff. Whenever it is slid, the current location
in the other file needs to be adjusted.
But these simple concepts are obfuscated by a lot of index handling that
is written in terse, subtle, and varied patterns. I found it very hard
to convince myself that the function was correct.
So introduce a "struct group" that represents a group of changed lines
in a file. Add some functions that perform elementary operations on
groups:
* Initialize a group to the first group in a file
* Move to the next or previous group in a file
* Slide a group up or down
Even though the resulting code is longer, I think it is easier to
understand and review. Its performance is not changed
appreciably (though it would be if `group_next()` and `group_previous()`
were not inlined).
...and in fact, the rewriting helped me discover another bug in the
--compaction-heuristic code: The update of blank_lines was never done
for the highest possible position of the group. This means that it could
fail to slide the group to its highest possible position, even if that
position had a blank line as its last line. So for example, it yielded
the following diff:
$ git diff --no-index --compaction-heuristic a.txt b.txt
diff --git a/a.txt b/b.txt
index e53969f..0d60c5fe 100644
--- a/a.txt
+++ b/b.txt
@@ -1,3 +1,7 @@
1
A
+
+B
+
+A
2
when in fact the following diff is better (according to the rules of
--compaction-heuristic):
$ git diff --no-index --compaction-heuristic a.txt b.txt
diff --git a/a.txt b/b.txt
index e53969f..0d60c5fe 100644
--- a/a.txt
+++ b/b.txt
@@ -1,3 +1,7 @@
1
+A
+
+B
+
A
2
The new code gives the bottom answer.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There is no reason for it to take an array and two indexes as argument,
as it only accesses two elements of the array.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There is no reason for it to take an array and index as argument, as it
only accesses a single element of the array.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If the changed group of lines can be matched to a group in the other
file, then that positioning should take precedence over the compaction
heuristic.
The old code tried the heuristic unconditionally, which cost redundant
effort and also was broken if the matching code had already shifted the
group higher than the blank line.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The code branch used for the compaction heuristic forgot to keep ixo in
sync while the group was shifted. This is certainly wrong, as it causes
the two counters to get out of sync.
I *think* that this bug could also have caused the function to read past
the end of the rchgo array, though I haven't done the work to prove it
for sure. Here is my reasoning:
If ixo is not decremented correctly during one iteration of the outer
while loop, then it will loose sync with the ix counter. In particular,
ixo will be too large.
Suppose that the next iterations of the outer while loop (i.e.,
processing the next block of add/delete lines) don't have any sliders.
Then the ixo counter would be incremented by the number of non-changed
lines in xdf, which is the same as the number of non-changed lines in
xdfo that *should have* followed the group that experienced the
malfunction. But since ixo was too large at the end of that iteration,
it will be incremented past the end of the xdfo->rchg array, and will
try to read that memory illegally.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
An age old bug that caused "git diff --ignore-space-at-eol"
misbehave has been fixed.
* js/ignore-space-at-eol:
diff: fix a double off-by-one with --ignore-space-at-eol
diff: demonstrate a bug with --patience and --ignore-space-at-eol
When comparing two lines, ignoring any whitespace at the end, we first
try to match as many bytes as possible and break out of the loop only
upon mismatch, to let the remainder be handled by the code shared with
the other whitespace-ignoring code paths.
When comparing the bytes, however, we incremented the counters always,
even if the bytes did not match. And because we fall through to the
space-at-eol handling at that point, it is as if that mismatch never
happened.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git show -W" (extend hunks to cover the entire function, delimited
by lines that match the "funcname" pattern) used to show the entire
file when a change added an entire function at the end of the file,
which has been fixed.
* rs/xdiff-hunk-with-func-line:
xdiff: fix merging of appended hunk with -W
grep: -W: don't extend context to trailing empty lines
t7810: add test for grep -W and trailing empty context lines
xdiff: don't trim common tail with -W
xdiff: -W: don't include common trailing empty lines in context
xdiff: ignore empty lines before added functions with -W
xdiff: handle appended chunks better with -W
xdiff: factor out match_func_rec()
t4051: rewrite, add more tests
"git show -W" (extend hunks to cover the entire function, delimited
by lines that match the "funcname" pattern) used to show the entire
file when a change added an entire function at the end of the file,
which has been fixed.
* rs/xdiff-hunk-with-func-line:
xdiff: fix merging of appended hunk with -W
grep: -W: don't extend context to trailing empty lines
t7810: add test for grep -W and trailing empty context lines
xdiff: don't trim common tail with -W
xdiff: -W: don't include common trailing empty lines in context
xdiff: ignore empty lines before added functions with -W
xdiff: handle appended chunks better with -W
xdiff: factor out match_func_rec()
t4051: rewrite, add more tests
When -W is given we search the lines between the end of the current
context and the next change for a function line. If there is none then
we merge those two hunks as they must be part of the same function.
If the next change is an appended chunk we abort the search early in
get_func_line(), however, because its line number is out of range. Fix
that by searching from the end of the pre-image in that case instead.
Reported-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Empty lines between functions are shown by diff -W, as it considers them
to be part of the function preceding them. They are not interesting in
most languages. The previous patch stopped showing them in the special
case of a function added at the end of a file.
Stop extending context to those empty lines by skipping back over them
from the start of the next function.
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If a new function and a preceding empty line is appended, diff -W shows
the previous function in full in order to provide context for that empty
line. In most languages empty lines between sections are not
interesting in and off themselves and showing a whole extra function for
them is not what we want.
Skip empty lines when checking of the appended chunk starts with a
function line, thereby avoiding to extend the context just for them.
Helped-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If lines are added at the end of a file, diff -W shows the whole file.
That's because get_func_line() only considers the pre-image and gives up
if it sees a record index beyond its end.
Consider the post-image as well to see if the added lines already make
up a full function. If it doesn't then search for the previous function
line by starting from the bottom of the pre-image, thereby avoiding to
confuse get_func_line().
Reuse the existing label called "again", as it's exactly where we need
to jump to when we're done handling the pre-context, but rename it to
"post_context_calculation" in order to document its new purpose better.
Reported-by: Junio C Hamano <gitster@pobox.com>
Initial-patch-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add match_func_rec(), a helper that wraps accessing a record and calling
the appropriate function for checking if it contains a function line.
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Patch output from "git diff" and friends has been tweaked to be
more readable by using a blank line as a strong hint that the
contents before and after it belong to a logically separate unit.
* jk/diff-compact-heuristic:
diff: undocument the compaction heuristic knobs for experimentation
xdiff: implement empty line chunk heuristic
xdiff: add recs_match helper function
In order to produce the smallest possible diff and combine several diff
hunks together, we implement a heuristic from GNU Diff which moves diff
hunks forward as far as possible when we find common context above and
below a diff hunk. This sometimes produces less readable diffs when
writing C, Shell, or other programming languages, ie:
...
/*
+ *
+ *
+ */
+
+/*
...
instead of the more readable equivalent of
...
+/*
+ *
+ *
+ */
+
/*
...
Implement the following heuristic to (optionally) produce the desired
output.
If there are diff chunks which can be shifted around, shift each hunk
such that the last common empty line is below the chunk with the rest
of the context above.
This heuristic appears to resolve the above example and several other
common issues without producing significantly weird results. However, as
with any heuristic it is not really known whether this will always be
more optimal. Thus, it can be disabled via diff.compactionHeuristic.
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It is a common pattern in xdl_change_compact to check that hashes and
strings match. The resulting code to perform this change causes very
long lines and makes it hard to follow the intention. Introduce a helper
function recs_match which performs both checks to increase
code readability.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A small memory leak in an error codepath has been plugged in xdiff
code.
* rj/xdiff-prepare-plug-leak-on-error-codepath:
xdiff/xprepare: fix a memory leak
xdiff/xprepare: use the XDF_DIFF_ALG() macro to access flag bits
The xdl_prepare_env() function may initialise an xdlclassifier_t
data structure via xdl_init_classifier(), which allocates memory
to several fields, for example 'rchash', 'rcrecs' and 'ncha'.
If this function later exits due to the failure of xdl_optimize_ctxs(),
then this xdlclassifier_t structure, and the memory allocated to it,
is not cleaned up.
In order to fix the memory leak, insert a call to xdl_free_classifier()
before returning.
Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit 307ab20b3 ("xdiff: PATIENCE/HISTOGRAM are not independent option
bits", 19-02-2012) introduced the XDF_DIFF_ALG() macro to access the
flag bits used to represent the diff algorithm requested. In addition,
code which had used explicit manipulation of the flag bits was changed
to use the macros.
However, one example of direct manipulation remains. Update this code to
use the XDF_DIFF_ALG() macro.
Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git merge-tree" used to mishandle "both sides added" conflict with
its own "create a fake ancestor file that has the common parts of
what both sides have added and do a 3-way merge" logic; this has
been updated to use the usual "3-way merge with an empty blob as
the fake common ancestor file" approach used in the rest of the
system.
* jk/no-diff-emit-common:
xdiff: drop XDL_EMIT_COMMON
merge-tree: drop generate_common strategy
merge-one-file: use empty blob for add/add base
When building the script for the second file that is to be merged
we have already allocated memory for data structures related to
the first file. When we encounter an error in building the second
script we only free allocated memory related to the second file
before erroring out.
Fix this memory leak by also releasing allocated memory related
to the first file.
Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There are no more callers that use this mode, and none
likely to be added (as our xdl_merge() eliminates the common
use of it for generating 3-way merge bases).
This is effectively a revert of a9ed376 (xdiff: generate
"anti-diffs" aka what is common to two files, 2006-06-28),
though of course trying to revert that ancient commit
directly produces many textual conflicts.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the previous patch, we made sure that the conflict markers themselves
match the end-of-line style of the input files. However, this still left
out the conflicting text itself: if it lacks a trailing newline, we
add one, and should add a carriage return when appropriate, too.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When merging files with CR/LF line endings, the conflict markers should
match those, lest the output file has mixed line endings.
This is particularly of interest on Windows, where some editors get
*really* confused by mixed line endings.
The original version of this patch by Beat Bolli respected core.eol, and
a subsequent improvement by this developer also respected gitattributes.
This approach was suboptimal, though: `git merge-file` was invented as a
drop-in replacement for GNU merge and as such has no problem operating
outside of any repository at all!
Another problem with the original approach was pointed out by Junio
Hamano: legacy repositories might have their text files committed using
CR/LF line endings (and core.eol and the gitattributes would give us a
false impression there). Therefore, the much superior approach is to
simply match the context's line endings, if any.
We actually do not have to look at the *entire* context at all: if the
files are all LF-only, or if they all have CR/LF line endings, it is
sufficient to look at just a *single* line to match that style. And if
the line endings are mixed anyway, it is *still* okay to imitate just a
single line's eol: we will just add to the pile of mixed line endings,
and there is nothing we can do about that.
So what we do is: we look at the line preceding the conflict, falling
back to the line preceding that in case it was the last line and had no
line ending, falling back to the first line, first in the first
post-image, then the second post-image, and finally the pre-image.
If we find consistent CR/LF (or undecided) end-of-line style, we match
that, otherwise we use LF-only line endings for the conflict markers.
Note that while it is true that there have to be at least two lines we
can look at (otherwise there would be no conflict), the same is not true
for line *endings*: the three files in question could all consist of a
single line without any line ending, each. In this case we fall back to
using LF-only.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If 'current-file' does not contain LF at EOF, and change between
'base-file' and 'other-file' does not change any line close to EOF, the
3-way merge should not add LF to EOF. This is what 'diff3 -m' does, and
seems to be a reasonable expectation.
The change which introduced the behavior is cd1d61c44f. It always calls
function xdl_recs_copy() for sides with add_nl == 1. In fact, it looks
like the only case when this is needed is when 2 files are being
union-merged, and they do not have LF at EOF (strictly speaking, the
first of them).
Add tests:
* "merge without conflict (missing LF at EOF, away from change in the
other file)" and "merge does not add LF away of change", to demonstrate
the changed behavior.
* "conflict at EOF without LF resolved by --union", to verify that the
union-merge at the end inerts newline between versions.
* some more tests which I felt like not covering the functionality well
Signed-off-by: Max Kirillov <max@max630.net>
Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Correct all hits from
git grep -e '\(&&\|||\)[^ ]' -e '[^ ]\(&&\|||\)' -- '*.c'
i.e. && or || operators that are followed by anything but a SP,
or that follow something other than a SP or a HT, so that these
operators have a SP around it when necessary.
We usually refrain from making this kind of a tree-wide change in
order to avoid unnecessary conflicts with other "real work" patches,
but in this case, the end result does not have a potentially
cumbersome tree-wide impact, while this is a tree-wide cleanup.
Fixes to compat/regex/regcomp.c and xdiff/xemit.c are to replace a
HT immediately after && with a SP.
This is based on Felipe's patch to bultin/symbolic-ref.c; I did all
the finding out what other files in the whole tree need to be fixed
and did the fix and also the log message while reviewing that single
liner, so any screw-ups in this version are mine.
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The goal of the patch is to introduce the GNU diff
-B/--ignore-blank-lines as closely as possible. The short option is not
available because it's already used for "break-rewrites".
When this option is used, git-diff will not create hunks that simply
add or remove empty lines, but will still show empty lines
addition/suppression if they are close enough to "valuable" changes.
There are two differences between this option and GNU diff -B option:
- GNU diff doesn't have "--inter-hunk-context", so this must be handled
- The following sequence looks like a bug (context is displayed twice):
$ seq 5 >file1
$ cat <<EOF >file2
change
1
2
3
4
5
change
EOF
$ diff -u -B file1 file2
--- file1 2013-06-08 22:13:04.471517834 +0200
+++ file2 2013-06-08 22:13:23.275517855 +0200
@@ -1,5 +1,7 @@
+change
1
2
+
3
4
5
@@ -3,3 +5,4 @@
3
4
5
+change
So here is a more thorough description of the option:
- real changes are interesting
- blank lines that are close enough (less than context size) to
interesting changes are considered interesting (recursive definition)
- "context" lines are used around each hunk of interesting changes
- If two hunks are separated by less than "inter-hunk-context", they
will be merged into one.
The implementation does the "interesting changes selection" in a single
pass.
Signed-off-by: Antoine Pelisse <apelisse@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Most of these were found using Lucas De Marchi's codespell tool.
Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Acked-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Import the latest 32-bit implementation of count_masked_bytes() from
Linux (arch/x86/include/asm/word-at-a-time.h). It's shorter and avoids
overflows and negative numbers.
This fixes test failures on 32-bit, where negative partial results had
been shifted right using the "wrong" method (logical shift right instead
of arithmetic short right). The compiler is free to chose the method,
so it was only wrong in the sense that it didn't work as intended by us.
Reported-by: Øyvind A. Holm <sunny@sunbase.org>
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Hide literals that can cause compiler warnings for 32-bit architectures in
expressions that evaluate to small numbers there. Some compilers warn that
0x0001020304050608 won't fit into a 32-bit long, others that shifting right
by 56 bits clears a 32-bit value completely.
The correct values are calculated in the 64-bit case, which is all that matters
in this if-branch.
Reported-by: Øyvind A. Holm <sunny@sunbase.org>
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Acked-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Import macro REPEAT_BYTE from Linux (arch/x86/include/asm/word-at-a-time.h)
to avoid 64-bit integer literals, which cause some 32-bit compilers to
print warnings.
Reported-by: Øyvind A. Holm <sunny@sunbase.org>
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The functions xdl_cha_first(), xdl_cha_next() and xdl_atol() are not used
by us. While removing them increases the difference to the upstream
version of libxdiff, it only adds a bit to the more than 600 differing
lines in xutils.c (mmfile_t management was simplified significantly when
the library was imported initially). Besides, if upstream modifies these
functions in the future, we won't need to think about importing those
changes, so in that sense it makes tracking modifications easier.
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a way to register a callback function that is gets passed the
start line and line count of each hunk of a diff. Only standard
types are used.
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Use word-at-a-time comparison to find end of line or NUL (end of buffer),
borrowed from the linux-kernel discussion.
By Thomas Rast
* tr/xdiff-fast-hash:
xdiff: choose XDL_FAST_HASH code on sizeof(long) instead of __WORDSIZE
xdiff: load full words in the inner loop of xdl_hash_record
