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git/Documentation/diff-config.txt

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diff.autoRefreshIndex::
When using 'git diff' to compare with work tree
files, do not consider stat-only change as changed.
Instead, silently run `git update-index --refresh` to
update the cached stat information for paths whose
contents in the work tree match the contents in the
index. This option defaults to true. Note that this
affects only 'git diff' Porcelain, and not lower level
'diff' commands such as 'git diff-files'.
diff.dirstat::
A comma separated list of `--dirstat` parameters specifying the
default behavior of the `--dirstat` option to linkgit:git-diff[1]`
and friends. The defaults can be overridden on the command line
(using `--dirstat=<param1,param2,...>`). The fallback defaults
(when not changed by `diff.dirstat`) are `changes,noncumulative,3`.
The following parameters are available:
+
--
`changes`;;
Compute the dirstat numbers by counting the lines that have been
removed from the source, or added to the destination. This ignores
the amount of pure code movements within a file. In other words,
rearranging lines in a file is not counted as much as other changes.
This is the default behavior when no parameter is given.
New --dirstat=lines mode, doing dirstat analysis based on diffstat This patch adds an alternative implementation of show_dirstat(), called show_dirstat_by_line(), which uses the more expensive diffstat analysis (as opposed to show_dirstat()'s own (relatively inexpensive) analysis) to derive the numbers from which the --dirstat output is computed. The alternative implementation is controlled by the new "lines" parameter to the --dirstat option (or the diff.dirstat config variable). For binary files, the diffstat analysis counts bytes instead of lines, so to prevent binary files from dominating the dirstat results, the byte counts for binary files are divided by 64 before being compared to their textual/line-based counterparts. This is a stupid and ugly - but very cheap - heuristic. In linux-2.6.git, running the three different --dirstat modes: time git diff v2.6.20..v2.6.30 --dirstat=changes > /dev/null vs. time git diff v2.6.20..v2.6.30 --dirstat=lines > /dev/null vs. time git diff v2.6.20..v2.6.30 --dirstat=files > /dev/null yields the following average runtimes on my machine: - "changes" (default): ~6.0 s - "lines": ~9.6 s - "files": ~0.1 s So, as expected, there's a considerable performance hit (~60%) by going through the full diffstat analysis as compared to the default "changes" analysis (obviously, "files" is much faster than both). As such, the "lines" mode is probably only useful if you really need the --dirstat numbers to be consistent with the numbers returned from the other --*stat options. The patch also includes documentation and tests for the new dirstat mode. Improved-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Johan Herland <johan@herland.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-04-29 11:36:21 +02:00
`lines`;;
Compute the dirstat numbers by doing the regular line-based diff
analysis, and summing the removed/added line counts. (For binary
files, count 64-byte chunks instead, since binary files have no
natural concept of lines). This is a more expensive `--dirstat`
behavior than the `changes` behavior, but it does count rearranged
lines within a file as much as other changes. The resulting output
is consistent with what you get from the other `--*stat` options.
`files`;;
Compute the dirstat numbers by counting the number of files changed.
Each changed file counts equally in the dirstat analysis. This is
the computationally cheapest `--dirstat` behavior, since it does
not have to look at the file contents at all.
`cumulative`;;
Count changes in a child directory for the parent directory as well.
Note that when using `cumulative`, the sum of the percentages
reported may exceed 100%. The default (non-cumulative) behavior can
be specified with the `noncumulative` parameter.
<limit>;;
An integer parameter specifies a cut-off percent (3% by default).
Directories contributing less than this percentage of the changes
are not shown in the output.
--
+
Example: The following will count changed files, while ignoring
directories with less than 10% of the total amount of changed files,
and accumulating child directory counts in the parent directories:
`files,10,cumulative`.
diff.statGraphWidth::
Limit the width of the graph part in --stat output. If set, applies
to all commands generating --stat output except format-patch.
diff.context::
Generate diffs with <n> lines of context instead of the default
of 3. This value is overridden by the -U option.
diff.interHunkContext::
Show the context between diff hunks, up to the specified number
of lines, thereby fusing the hunks that are close to each other.
This value serves as the default for the `--inter-hunk-context`
command line option.
diff.external::
If this config variable is set, diff generation is not
performed using the internal diff machinery, but using the
given command. Can be overridden with the `GIT_EXTERNAL_DIFF'
environment variable. The command is called with parameters
as described under "git Diffs" in linkgit:git[1]. Note: if
you want to use an external diff program only on a subset of
your files, you might want to use linkgit:gitattributes[5] instead.
diff.ignoreSubmodules::
Sets the default value of --ignore-submodules. Note that this
affects only 'git diff' Porcelain, and not lower level 'diff'
commands such as 'git diff-files'. 'git checkout' also honors
this setting when reporting uncommitted changes. Setting it to
'all' disables the submodule summary normally shown by 'git commit'
and 'git status' when `status.submoduleSummary` is set unless it is
overridden by using the --ignore-submodules command-line option.
The 'git submodule' commands are not affected by this setting.
diff.mnemonicPrefix::
If set, 'git diff' uses a prefix pair that is different from the
standard "a/" and "b/" depending on what is being compared. When
this configuration is in effect, reverse diff output also swaps
the order of the prefixes:
`git diff`;;
compares the (i)ndex and the (w)ork tree;
`git diff HEAD`;;
compares a (c)ommit and the (w)ork tree;
`git diff --cached`;;
compares a (c)ommit and the (i)ndex;
`git diff HEAD:file1 file2`;;
compares an (o)bject and a (w)ork tree entity;
`git diff --no-index a b`;;
compares two non-git things (1) and (2).
diff.noprefix::
If set, 'git diff' does not show any source or destination prefix.
diff.orderFile::
File indicating how to order files within a diff.
See the '-O' option to linkgit:git-diff[1] for details.
If `diff.orderFile` is a relative pathname, it is treated as
relative to the top of the working tree.
diff.renameLimit::
The number of files to consider when performing the copy/rename
detection; equivalent to the 'git diff' option `-l`.
diff.renames::
Whether and how Git detects renames. If set to "false",
rename detection is disabled. If set to "true", basic rename
detection is enabled. If set to "copies" or "copy", Git will
detect copies, as well. Defaults to true. Note that this
affects only 'git diff' Porcelain like linkgit:git-diff[1] and
linkgit:git-log[1], and not lower level commands such as
linkgit:git-diff-files[1].
diff.suppressBlankEmpty::
A boolean to inhibit the standard behavior of printing a space
before each empty output line. Defaults to false.
diff.submodule::
Specify the format in which differences in submodules are
shown. The "short" format just shows the names of the commits
at the beginning and end of the range. The "log" format lists
the commits in the range like linkgit:git-submodule[1] `summary`
does. The "diff" format shows an inline diff of the changed
contents of the submodule. Defaults to "short".
diff.wordRegex::
A POSIX Extended Regular Expression used to determine what is a "word"
when performing word-by-word difference calculations. Character
sequences that match the regular expression are "words", all other
characters are *ignorable* whitespace.
diff.<driver>.command::
The custom diff driver command. See linkgit:gitattributes[5]
for details.
diff.<driver>.xfuncname::
The regular expression that the diff driver should use to
recognize the hunk header. A built-in pattern may also be used.
See linkgit:gitattributes[5] for details.
diff.<driver>.binary::
Set this option to true to make the diff driver treat files as
binary. See linkgit:gitattributes[5] for details.
diff.<driver>.textconv::
The command that the diff driver should call to generate the
text-converted version of a file. The result of the
conversion is used to generate a human-readable diff. See
linkgit:gitattributes[5] for details.
diff.<driver>.wordRegex::
The regular expression that the diff driver should use to
split words in a line. See linkgit:gitattributes[5] for
details.
diff.<driver>.cachetextconv::
Set this option to true to make the diff driver cache the text
conversion outputs. See linkgit:gitattributes[5] for details.
diff.tool::
Controls which diff tool is used by linkgit:git-difftool[1].
This variable overrides the value configured in `merge.tool`.
The list below shows the valid built-in values.
Any other value is treated as a custom diff tool and requires
that a corresponding difftool.<tool>.cmd variable is defined.
include::mergetools-diff.txt[]
diff: improve positioning of add/delete blocks in diffs 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>
2016-09-05 11:44:51 +02:00
diff.indentHeuristic::
Set this option to `true` to enable experimental heuristics
that shift diff hunk boundaries to make patches easier to read.
diff.algorithm::
Choose a diff algorithm. The variants are as follows:
+
--
`default`, `myers`;;
The basic greedy diff algorithm. Currently, this is the default.
`minimal`;;
Spend extra time to make sure the smallest possible diff is
produced.
`patience`;;
Use "patience diff" algorithm when generating patches.
`histogram`;;
This algorithm extends the patience algorithm to "support
low-occurrence common elements".
--
+
diff.wsErrorHighlight::
Highlight whitespace errors in the `context`, `old` or `new`
lines of the diff. Multiple values are separated by comma,
`none` resets previous values, `default` reset the list to
`new` and `all` is a shorthand for `old,new,context`. The
whitespace errors are colored with `color.diff.whitespace`.
The command line option `--ws-error-highlight=<kind>`
overrides this setting.