summaryrefslogtreecommitdiff
path: root/combine-diff.c
AgeCommit message (Collapse)AuthorFilesLines
2013-07-29many small typofixesLibravatar Ondřej Bílka1-1/+1
Signed-off-by: Ondřej Bílka <neleai@seznam.cz> Reviewed-by: Marc Branchaud <marcnarc@xiplink.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-06-11Merge branch 'cb/log-follow-with-combined'Libravatar Junio C Hamano1-0/+3
* cb/log-follow-with-combined: fix segfault with git log -c --follow
2013-06-02Merge branch 'mk/combine-diff-context-horizon-fix'Libravatar Junio C Hamano1-2/+5
"git diff -c -p" was not showing a deleted line from a hunk when another hunk immediately begins where the earlier one ends. * mk/combine-diff-context-horizon-fix: combine-diff.c: Fix output when changes are exactly 3 lines apart
2013-05-28fix segfault with git log -c --followLibravatar Clemens Buchacher1-0/+3
In diff_tree_combined we make a copy of diffopts. In try_to_follow_renames, called via diff_tree_sha1, we free and re-initialize diffopts->pathspec->items. Since we did not make a deep copy of diffopts in diff_tree_combined, the original diffopts does not get the update. By the time we return from diff_tree_combined, rev->diffopt->pathspec->items points to an invalid memory address. We get a segfault next time we try to access that pathspec. Instead, along with the copy of diffopts, make a copy pathspec->items as well. We would also have to make a copy of pathspec->raw to keep it consistent with pathspec->items, but nobody seems to rely on that. Signed-off-by: Clemens Buchacher <drizzd@aon.at> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-05-15combine-diff.c: Fix output when changes are exactly 3 lines apartLibravatar Matthijs Kooijman1-2/+5
When a deletion is followed by exactly 3 (or whatever the number of context lines) unchanged lines, followed by another change, the combined diff output would hide the first deletion, resulting in a malformed diff. This happened because the 3 lines before each change are painted interesting, but also marked as no_pre_delete to prevent showing deletes that were previously marked as uninteresting. This behaviour was introduced in c86fbe53 (diff -c/--cc: do not include uninteresting deletion before leading context). However, as a side effect, this could also mark deletes that were already interesting as no_pre_delete. This would happen only if the delete was exactly 3 lines away from the next change, since lines farther away would not be touched by the "paint three lines before the change" code and lines closer would be painted by the "merge two adjacent hunks" code instead, which does not set the no_pre_delete flag. This commit fixes this problem by only setting the no_pre_delete flag for changes that were previously uninteresting. Signed-off-by: Matthijs Kooijman <matthijs@stdin.nl> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-03-25combine-diff: coalesce lost lines optimallyLibravatar Antoine Pelisse1-64/+191
This replaces the greedy implementation to coalesce lost lines by using dynamic programming to find the Longest Common Subsequence. The O(n²) time complexity is obviously bigger than previous implementation but it can produce shorter diff results (and most likely easier to read). List of lost lines is now doubly-linked because we reverse-read it when reading the direction matrix. Signed-off-by: Antoine Pelisse <apelisse@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-03-14Allow combined diff to ignore white-spacesLibravatar Antoine Pelisse1-7/+50
The combined diff --cc output does not honor options to ignore whitespace changes (-b, -w, and --ignore-space-at-eol). Correct this by passing diff flags to diff engine, so that combined diff behaves as normal diff does with spaces, and by coalescing lines that are removed from both (or more) parents, honoring the same rule to ignore whitespace changes. With this change, a conflict-less merge done using a ignore-* strategy option will not show any conflict if shown in combined-diff using the same option. Signed-off-by: Antoine Pelisse <apelisse@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-02-14Merge branch 'jk/diff-graph-cleanup'Libravatar Junio C Hamano1-17/+32
Refactors a lot of repetitive code sequence from the graph drawing code and adds it to the combined diff output. * jk/diff-graph-cleanup: combine-diff.c: teach combined diffs about line prefix diff.c: use diff_line_prefix() where applicable diff: add diff_line_prefix function diff.c: make constant string arguments const diff: write prefix to the correct file graph: output padding for merge subsequent parents
2013-02-12combine-diff.c: teach combined diffs about line prefixLibravatar John Keeping1-17/+30
When running "git log --graph --cc -p" the diff output for merges is not indented by the graph structure, unlike the diffs of non-merge commits (added in commit 7be5761 - diff.c: Output the text graph padding before each diff line). Fix this by teaching the combined diff code to output diff_line_prefix() before each line. Signed-off-by: John Keeping <john@keeping.me.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-02-03combine-diff: lift 32-way limit of combined diffLibravatar Junio C Hamano1-14/+7
The "raw" format of combine-diff output is supposed to have as many colons as there are parents at the beginning, then blob modes for these parents, and then object names for these parents. We weren't however prepared to handle a more than 32-way merge and did not show the correct number of colons in such a case. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-09-10Merge branch 'jk/maint-null-in-trees' into maint-1.7.11Libravatar Junio C Hamano1-2/+2
"git diff" had a confusion between taking data from a path in the working tree and taking data from an object that happens to have name 0{40} recorded in a tree. * jk/maint-null-in-trees: fsck: detect null sha1 in tree entries do not write null sha1s to on-disk index diff: do not use null sha1 as a sentinel value
2012-08-27Merge branch 'jk/maint-null-in-trees'Libravatar Junio C Hamano1-2/+2
We do not want a link to 0{40} object stored anywhere in our objects. * jk/maint-null-in-trees: fsck: detect null sha1 in tree entries do not write null sha1s to on-disk index diff: do not use null sha1 as a sentinel value
2012-07-29diff: do not use null sha1 as a sentinel valueLibravatar Jeff King1-2/+2
The diff code represents paths using the diff_filespec struct. This struct has a sha1 to represent the sha1 of the content at that path, as well as a sha1_valid member which indicates whether its sha1 field is actually useful. If sha1_valid is not true, then the filespec represents a working tree file (e.g., for the no-index case, or for when the index is not up-to-date). The diff_filespec is only used internally, though. At the interfaces to the diff subsystem, callers feed the sha1 directly, and we create a diff_filespec from it. It's at that point that we look at the sha1 and decide whether it is valid or not; callers may pass the null sha1 as a sentinel value to indicate that it is not. We should not typically see the null sha1 coming from any other source (e.g., in the index itself, or from a tree). However, a corrupt tree might have a null sha1, which would cause "diff --patch" to accidentally diff the working tree version of a file instead of treating it as a blob. This patch extends the edges of the diff interface to accept a "sha1_valid" flag whenever we accept a sha1, and to use that flag when creating a filespec. In some cases, this means passing the flag through several layers, making the code change larger than would be desirable. One alternative would be to simply die() upon seeing corrupted trees with null sha1s. However, this fix more directly addresses the problem (while bogus sha1s in a tree are probably a bad thing, it is really the sentinel confusion sending us down the wrong code path that is what makes it devastating). And it means that git is more capable of examining and debugging these corrupted trees. For example, you can still "diff --raw" such a tree to find out when the bogus entry was introduced; you just cannot do a "--patch" diff (just as you could not with any other corrupted tree, as we do not have any content to diff). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-04-16Merge branch 'rs/combine-diff-zero-context-at-the-beginning'Libravatar Junio C Hamano1-1/+1
Fixes an age old corner case bug in combine diff (only triggered with -U0 and the hunk at the beginning of the file needs to be shown). By René Scharfe * rs/combine-diff-zero-context-at-the-beginning: combine-diff: fix loop index underflow
2012-03-25combine-diff: fix loop index underflowLibravatar René Scharfe1-1/+1
If both la and context are zero at the start of the loop, la wraps around and we end up reading from memory far away. Skip the loop in that case instead. Reported-by: Julia Lawall <julia.lawall@lip6.fr> Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-12-17pass struct commit to diff_tree_combined_merge()Libravatar René Scharfe1-4/+3
Instead of passing the hash of a commit and then searching that same commit in the single caller, simply pass the commit directly. Signed-off-by: René Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-12-17use struct sha1_array in diff_tree_combined()Libravatar René Scharfe1-21/+13
Maintaining an array of hashes is easier using sha1_array than open-coding it. This patch also fixes a leak of the SHA1 array in diff_tree_combined_merge(). Signed-off-by: René Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-08-28Merge branch 'jk/color-and-pager'Libravatar Junio C Hamano1-4/+3
* jk/color-and-pager: want_color: automatically fallback to color.ui diff: don't load color config in plumbing config: refactor get_colorbool function color: delay auto-color decision until point of use git_config_colorbool: refactor stdout_is_tty handling diff: refactor COLOR_DIFF from a flag into an int setup_pager: set GIT_PAGER_IN_USE t7006: use test_config helpers test-lib: add helper functions for config t7006: modernize calls to unset Conflicts: builtin/commit.c parse-options.c
2011-08-28Merge branch 'jc/combine-diff-callback'Libravatar Junio C Hamano1-0/+69
* jc/combine-diff-callback: combine-diff: support format_callback
2011-08-20combine-diff: support format_callbackLibravatar Junio C Hamano1-0/+69
This teaches combine-diff machinery to feed a combined merge to a callback function when DIFF_FORMAT_CALLBACK is specified. So far, format callback functions are not used for anything but 2-way diffs. A callback is given a diff_queue_struct, which is an array of diff_filepair. As its name suggests, a diff_filepair is a _pair_ of diff_filespec that represents a single preimage and a single postimage. Since "diff -c" is to compare N parents with a single merge result and filter out any paths whose result match one (or more) of the parent(s), its output has to be able to represent N preimages and 1 postimage. For this reason, a callback function that inspects a diff_filepair that results from this new infrastructure can and is expected to view the preimage side (i.e. pair->one) as an array of diff_filespec. Each element in the array, except for the last one, is marked with "has_more_entries" bit, so that the same callback function can be used for 2-way diffs and combined diffs. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-08-18diff: refactor COLOR_DIFF from a flag into an intLibravatar Jeff King1-4/+3
This lets us store more than just a bit flag for whether we want color; we can also store whether we want automatic colors. This can be useful for making the automatic-color decision closer to the point of use. This mostly just involves replacing DIFF_OPT_* calls with manipulations of the flag. The biggest exception is that calls to DIFF_OPT_TST must check for "o->use_color > 0", which lets an "unknown" value (i.e., the default) stay at "no color". In the previous code, a value of "-1" was not propagated at all. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-08-17Merge branch 'jc/maint-combined-diff-work-tree'Libravatar Junio C Hamano1-4/+10
* jc/maint-combined-diff-work-tree: diff -c/--cc: do not mistake "resolved as deletion" as "use working tree" Conflicts: combine-diff.c
2011-08-04diff -c/--cc: do not mistake "resolved as deletion" as "use working tree"Libravatar Junio C Hamano1-4/+10
The combined diff machinery can be used to compare: - a merge commit with its parent commits; - a working-tree file with multiple stages in an unmerged index; or - a working-tree file with the HEAD and the index. The internal function combine-diff.c:show_patch_diff() checked if it needs to read the "result" from the working tree by looking at the object name of the result --- if it is null_sha1, it read from the working tree. This mistook a merge that records a deletion as the conflict resolution as if it is a cue to read from the working tree. Pass this information explicitly from the caller instead. Noticed and reported by Johan Herland. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-05-24combine-diff: respect textconv attributesLibravatar Jeff King1-9/+32
When doing a combined diff, we did not respect textconv attributes at all. This generally lead to us printing "Binary files differ" when we could show a combined diff of the converted text. This patch converts file contents according to textconv attributes. The implementation is slightly ugly; because the textconv code is tightly linked with the diff_filespec code, we temporarily create a diff_filespec during conversion. In practice, though, this should not create a performance problem. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-05-23combine-diff: handle binary files as binaryLibravatar Jeff King1-2/+35
The combined diff code path is totally different from the regular diff code path, and didn't handle binary files at all. The results of a combined diff on a binary file could range from annoying (since we spewed binary garbage, possibly upsetting the user's terminal), to wrong (embedded NULs caused us to show incorrect diffs, with lines truncated at the NUL character), to potential security problems (embedded NULs could interfere with "-z" output, possibly defeating policy hooks which parse diff output). Instead, we consider a combined diff to be binary if any of the input blobs is binary. To show a binary combined diff, we indicate "Binary blobs differ"; the "index" meta line will show which parents had which blob. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-05-23combine-diff: calculate mode_differs earlierLibravatar Jeff King1-2/+7
One loop combined both the patch generation and checking whether there was any mode change to report. Let's factor that into two separate loops, as we may care about the mode change even if we are not generating patches (e.g., because we are showing a binary diff, which will come in a future patch). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-05-23combine-diff: split header printing into its own functionLibravatar Jeff King1-61/+74
This is a pretty big logical chunk, so it makes the function a bit more readable to have it split out. In addition, it will make it easier to add an alternate code path for binary diffs in a future patch. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-06-21Merge branch 'rs/diff-no-minimal' into maintLibravatar Junio C Hamano1-1/+1
* rs/diff-no-minimal: git diff too slow for a file
2010-06-13Merge branch 'rs/diff-no-minimal'Libravatar Junio C Hamano1-1/+1
* rs/diff-no-minimal: git diff too slow for a file
2010-05-04remove ecb parameter from xdi_diff_outf()Libravatar René Scharfe1-2/+1
xdi_diff_outf() overrides the structure members of its last parameter, ignoring any value that callers pass in. It's no surprise then that all callers pass a pointer to an uninitialized structure. They also don't read it after the call, so the parameter is neither used for input nor for output. Turn it into a local variable of xdi_diff_outf(). Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Acked-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-05-02git diff too slow for a fileLibravatar René Scharfe1-1/+1
Ever since the xdiff library had been introduced to git, all its callers have used the flag XDF_NEED_MINIMAL. It makes sure that the smallest possible diff is produced, but that takes quite some time if there are lots of differences that can be expressed in multiple ways. This flag makes a difference for only 0.1% of the non-merge commits in the git repo of Linux, both in terms of diff size and execution time. The patches there are mostly nice and small. SungHyun Nam however reported a case in a different repo where a diff took more than 20 times longer to generate with XDF_NEED_MINIMAL than without. Rebasing became really slow. This patch removes this flag from all callers. The default of xdiff is saner because it has minimal to no impact in the normal case of small diffs and doesn't incur that much of a speed penalty for large ones. A follow-up patch may introduce a command line option to set the flag if the user needs it, similar to GNU diff's -d/--minimal. Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-04-17combined diff: correctly handle truncated fileLibravatar Thomas Rast1-6/+8
Consider an evil merge of two commits A and B, both of which have a file 'foo', but the merge result does not have that file. The combined-diff code learned in 4462731 (combine-diff: do not punt on removed or added files., 2006-02-06) to concisely show only the removal, since that is the evil part and the previous contents are presumably uninteresting. However, to diagnose an empty merge result, it overloaded the variable that holds the file's length. This means that the check also triggers for truncated files. Consequently, such files were not shown in the diff at all despite the merge being clearly evil. Fix this by adding a new variable that distinguishes whether the file was deleted (which is the case 4462731 handled) or truncated. In the truncated case, we show the full combined diff again, which is rather spammy but at least does not hide the evilness. Reported-by: David Martínez Martí <desarrollo@gestiweb.com> Signed-off-by: Thomas Rast <trast@student.ethz.ch> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-11-28Give the hunk comment its own colorLibravatar Bert Wesarg1-1/+4
Inspired by the coloring of quilt. Introduce a separate color and paint the hunk comment part, i.e. the name of the function, in a separate color "diff.func" (defaults to plain). Whitespace between hunk header and hunk comment is printed in plain color. Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-07-22Merge branch 'maint'Libravatar Junio C Hamano1-15/+14
* maint: Trailing whitespace and no newline fix diff --cc: a lost line at the beginning of the file is shown incorrectly combine-diff.c: fix performance problem when folding common deleted lines
2009-07-22diff --cc: a lost line at the beginning of the file is shown incorrectlyLibravatar Junio C Hamano1-7/+9
When combine-diff inspected the diff from one parent to the merge result, it misinterpreted a header in the form @@ -l,k +0,0 @@. This hunk header means that K lines were removed from the beginning of the file, so the lost lines must be queued to the sline that represents the first line of the merge result, but we incremented our pointer incorrectly and ended up queuing it to the second line, which in turn made the lossage appear _after_ the first line. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-07-22combine-diff.c: fix performance problem when folding common deleted linesLibravatar Junio C Hamano1-8/+5
For a deleted line in a patch with the parent we are looking at, the append_lost() function finds the same line among a run of lines that were deleted from the same location by patches from parents we previously checked. This is so that patches with two parents @@ -1,4 +1,3 @@ @@ -1,4 +1,3 @@ one one -two -two three three -quatro -fyra +four +four can be coalesced into this sequence, reusing one line that describes the removal of "two" for both parents. @@@ -1,4 -1,4 +1,3 @@@ one --two three - quatro -frya ++four While reading the second patch (that removes "two" and then "fyra"), after finding where removal of the "two" matches, we need to find existing removal of "fyra" (if exists) in the removal list, but the match has to happen after all the existing matches (in this case "two"). The code used a naïve O(n^2) algorithm to compute this by scanning the whole removal list over and over again. This patch remembers where the next scan should be started in the existing removal list to avoid this. Noticed by Linus Torvalds. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-06-27Use die_errno() instead of die() when checking syscallsLibravatar Thomas Rast1-1/+1
Lots of die() calls did not actually report the kind of error, which can leave the user confused as to the real problem. Use die_errno() where we check a system/library call that sets errno on failure, or one of the following that wrap such calls: Function Passes on error from -------- -------------------- odb_pack_keep open read_ancestry fopen read_in_full xread strbuf_read xread strbuf_read_file open or strbuf_read_file strbuf_readlink readlink write_in_full xwrite Signed-off-by: Thomas Rast <trast@student.ethz.ch> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-05-01Fix a bunch of pointer declarations (codestyle)Libravatar Felipe Contreras1-2/+2
Essentially; s/type* /type */ as per the coding guidelines. Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-04-29Merge branch 'maint'Libravatar Junio C Hamano1-9/+25
* maint: diff -c -p: do not die on submodules Conflicts: combine-diff.c
2009-04-29Merge branch 'maint-1.6.0' into maint-1.6.1Libravatar Junio C Hamano1-12/+26
* maint-1.6.0: diff -c -p: do not die on submodules
2009-04-29diff -c -p: do not die on submodulesLibravatar Junio C Hamano1-12/+26
The combine diff logic knew only about blobs (and their checked-out form in the work tree, either regular files or symlinks), and barfed when fed submodules. This "externalizes" gitlinks in the same way as the normal patch generation codepath does (i.e. "Subproject commit Xxx\n") to fix the issue. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-03-17Merge branch 'kb/checkout-optim'Libravatar Junio C Hamano1-3/+1
* kb/checkout-optim: Revert "lstat_cache(): print a warning if doing ping-pong between cache types" checkout bugfix: use stat.mtime instead of stat.ctime in two places Makefile: Set compiler switch for USE_NSEC Create USE_ST_TIMESPEC and turn it on for Darwin Not all systems use st_[cm]tim field for ns resolution file timestamp Record ns-timestamps if possible, but do not use it without USE_NSEC write_index(): update index_state->timestamp after flushing to disk verify_uptodate(): add ce_uptodate(ce) test make USE_NSEC work as expected fix compile error when USE_NSEC is defined check_updates(): effective removal of cache entries marked CE_REMOVE lstat_cache(): print a warning if doing ping-pong between cache types show_patch_diff(): remove a call to fstat() write_entry(): use fstat() instead of lstat() when file is open write_entry(): cleanup of some duplicated code create_directories(): remove some memcpy() and strchr() calls unlink_entry(): introduce schedule_dir_for_removal() lstat_cache(): swap func(length, string) into func(string, length) lstat_cache(): generalise longest_match_lstat_cache() lstat_cache(): small cleanup and optimisation
2009-03-07Move local variables to narrower scopesLibravatar Benjamin Kramer1-2/+1
These weren't used outside and can be safely moved Signed-off-by: Benjamin Kramer <benny.kra@googlemail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-02-09show_patch_diff(): remove a call to fstat()Libravatar Kjetil Barvik1-3/+1
Currently inside show_patch_diff() we have an fstat() call after an ok lstat() call. Since before the call to fstat() we have already tested for the link case with S_ISLNK(), the fstat() can be removed. Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-12-17combine-diff.c: use strbuf_readlink()Libravatar Junio C Hamano1-5/+5
When showing combined diff using work tree contents, use strbuf_readlink() to read symbolic links. Signed-off-by: Junio C Hamano <gitster@pobox.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-25Always initialize xpparam_t to 0Libravatar Brian Downing1-0/+1
We're going to be adding some parameters to this, so we can't have any uninitialized data in it. Signed-off-by: Brian Downing <bdowning@lavos.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-10-12Replace calls to strbuf_init(&foo, 0) with STRBUF_INIT initializerLibravatar Brandon Casey1-2/+1
Many call sites use strbuf_init(&foo, 0) to initialize local strbuf variable "foo" which has not been accessed since its declaration. These can be replaced with a static initialization using the STRBUF_INIT macro which is just as readable, saves a function call, and takes up fewer lines. Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-09-18Merge branch 'jc/diff-prefix'Libravatar Junio C Hamano1-2/+6
* jc/diff-prefix: diff: vary default prefix depending on what are compared
2008-09-07Merge branch 'jc/hide-cr-in-diff-from-less'Libravatar Junio C Hamano1-2/+14
* jc/hide-cr-in-diff-from-less: diff: Help "less" hide ^M from the output
2008-08-30diff: vary default prefix depending on what are comparedLibravatar Junio C Hamano1-2/+6
With a new configuration "diff.mnemonicprefix", "git diff" shows the differences between various combinations of preimage and postimage trees with prefixes different from the standard "a/" and "b/". Hopefully this will make the distinction stand out for some people. "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). Because these mnemonics now have meanings, they are swapped when reverse diff is in effect and this feature is enabled. Signed-off-by: Junio C Hamano <gitster@pobox.com>