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authorJeff King <peff@peff.net>2016-08-31 05:05:38 (GMT)
committerJunio C Hamano <gitster@pobox.com>2016-08-31 16:59:53 (GMT)
commit3dbfe2b8ae94cbdae5f3d32581aedaa5510fdc87 (patch)
tree764f91156b2707cb6dc7c5a4cc4f8784203411bc /contrib/diff-highlight
parent1b5290b125fca91f620aadbc1a5e3c559d4a5313 (diff)
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diff-highlight: avoid highlighting combined diffs
The algorithm in diff-highlight only understands how to look at two sides of a diff; it cannot correctly handle combined diffs with multiple preimages. Often highlighting does not trigger at all for these diffs because the line counts do not match up. E.g., if we see: - ours -theirs ++resolved we would not bother highlighting; it naively looks like a single line went away, and then a separate hunk added another single line. But of course there are exceptions. E.g., if the other side deleted the line, we might see: - ours ++resolved which looks like we dropped " ours" and added "+resolved". This is only a small highlighting glitch (we highlight the space and the "+" along with the content), but it's also the tip of the iceberg. Even if we learned to find the true content here (by noticing we are in a 3-way combined diff and marking _two_ characters from the front of the line as uninteresting), there are other more complicated cases where we really do need to handle a 3-way hunk. Let's just punt for now; we can recognize combined diffs by the presence of extra "@" symbols in the hunk header, and treat them as non-diff content. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'contrib/diff-highlight')
-rwxr-xr-xcontrib/diff-highlight/diff-highlight2
-rwxr-xr-xcontrib/diff-highlight/t/t9400-diff-highlight.sh37
2 files changed, 38 insertions, 1 deletions
diff --git a/contrib/diff-highlight/diff-highlight b/contrib/diff-highlight/diff-highlight
index 9280c88..81bd804 100755
--- a/contrib/diff-highlight/diff-highlight
+++ b/contrib/diff-highlight/diff-highlight
@@ -36,7 +36,7 @@ $SIG{PIPE} = 'DEFAULT';
while (<>) {
if (!$in_hunk) {
print;
- $in_hunk = /^$GRAPH*$COLOR*\@/;
+ $in_hunk = /^$GRAPH*$COLOR*\@\@ /;
}
elsif (/^$GRAPH*$COLOR*-/) {
push @removed, $_;
diff --git a/contrib/diff-highlight/t/t9400-diff-highlight.sh b/contrib/diff-highlight/t/t9400-diff-highlight.sh
index b0fe7cc..3b43dbe 100755
--- a/contrib/diff-highlight/t/t9400-diff-highlight.sh
+++ b/contrib/diff-highlight/t/t9400-diff-highlight.sh
@@ -256,4 +256,41 @@ test_expect_success 'diff-highlight works with the --graph option' '
test_cmp graph.exp graph.act
'
+# Most combined diffs won't meet diff-highlight's line-number filter. So we
+# create one here where one side drops a line and the other modifies it. That
+# should result in a diff like:
+#
+# - modified content
+# ++resolved content
+#
+# which naively looks like one side added "+resolved".
+test_expect_success 'diff-highlight ignores combined diffs' '
+ echo "content" >file &&
+ git add file &&
+ git commit -m base &&
+
+ >file &&
+ git commit -am master &&
+
+ git checkout -b other HEAD^ &&
+ echo "modified content" >file &&
+ git commit -am other &&
+
+ test_must_fail git merge master &&
+ echo "resolved content" >file &&
+ git commit -am resolved &&
+
+ cat >expect <<-\EOF &&
+ --- a/file
+ +++ b/file
+ @@@ -1,1 -1,0 +1,1 @@@
+ - modified content
+ ++resolved content
+ EOF
+
+ git show -c | "$DIFF_HIGHLIGHT" >actual.raw &&
+ sed -n "/^---/,\$p" <actual.raw >actual &&
+ test_cmp expect actual
+'
+
test_done