Merge branch 'rs/diff-ihc'

* rs/diff-ihc:
  diff: add option to show context between close hunks

Conflicts:
	Documentation/diff-options.txt

7 files changed, 106 insertions, 1 deletions

diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index b432d2518..671f533ca 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -205,6 +205,10 @@ endif::git-format-patch[]
 	differences even if one line has whitespace where the other
 	line has none.
 
+--inter-hunk-context=<lines>::
+	Show the context between diff hunks, up to the specified number
+	of lines, thereby fusing hunks that are close to each other.
+
 --exit-code::
 	Make the program exit with codes similar to diff(1).
 	That is, it exits with 1 if there were differences and
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 3b25d4809..8ec782dc5 100755
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -776,6 +776,7 @@ _git_diff ()
 			--no-ext-diff
 			--no-prefix --src-prefix= --dst-prefix=
 			--base --ours --theirs
+			--inter-hunk-context=
 			"
 		return
 		;;
@@ -967,6 +968,7 @@ _git_log ()
 			--color-words --walk-reflogs
 			--parents --children --full-history
 			--merge
+			--inter-hunk-context=
 			"
 		return
 		;;
diff --git a/diff.c b/diff.c
index c159a5fc6..d23548292 100644
--- a/diff.c
+++ b/diff.c
@@ -1469,6 +1469,7 @@ static void builtin_diff(const char *name_a,
 		ecbdata.file = o->file;
 		xpp.flags = XDF_NEED_MINIMAL | o->xdl_opts;
 		xecfg.ctxlen = o->context;
+		xecfg.interhunkctxlen = o->interhunkcontext;
 		xecfg.flags = XDL_EMIT_FUNCNAMES;
 		if (pe)
 			xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
@@ -2538,6 +2539,9 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		options->b_prefix = arg + 13;
 	else if (!strcmp(arg, "--no-prefix"))
 		options->a_prefix = options->b_prefix = "";
+	else if (opt_arg(arg, '\0', "inter-hunk-context",
+			 &options->interhunkcontext))
+		;
 	else if (!prefixcmp(arg, "--output=")) {
 		options->file = fopen(arg + strlen("--output="), "w");
 		options->close_file = 1;
diff --git a/diff.h b/diff.h
index 42582edee..4d5a32781 100644
--- a/diff.h
+++ b/diff.h
@@ -78,6 +78,7 @@ struct diff_options {
 	const char *a_prefix, *b_prefix;
 	unsigned flags;
 	int context;
+	int interhunkcontext;
 	int break_opt;
 	int detect_rename;
 	int skip_stat_unmatch;
diff --git a/t/t4032-diff-inter-hunk-context.sh b/t/t4032-diff-inter-hunk-context.sh
new file mode 100755
index 000000000..e4e3e28fc
--- /dev/null
+++ b/t/t4032-diff-inter-hunk-context.sh
@@ -0,0 +1,92 @@
+#!/bin/sh
+
+test_description='diff hunk fusing'
+
+. ./test-lib.sh
+
+f() {
+	echo $1
+	i=1
+	while test $i -le $2
+	do
+		echo $i
+		i=$(expr $i + 1)
+	done
+	echo $3
+}
+
+t() {
+	case $# in
+	4) hunks=$4; cmd="diff -U$3";;
+	5) hunks=$5; cmd="diff -U$3 --inter-hunk-context=$4";;
+	esac
+	label="$cmd, $1 common $2"
+	file=f$1
+	expected=expected.$file.$3.$hunks
+
+	if ! test -f $file
+	then
+		f A $1 B >$file
+		git add $file
+		git commit -q -m. $file
+		f X $1 Y >$file
+	fi
+
+	test_expect_success "$label: count hunks ($hunks)" "
+		test $(git $cmd $file | grep '^@@ ' | wc -l) = $hunks
+	"
+
+	test -f $expected &&
+	test_expect_success "$label: check output" "
+		git $cmd $file | grep -v '^index ' >actual &&
+		test_cmp $expected actual
+	"
+}
+
+cat <<EOF >expected.f1.0.1 || exit 1
+diff --git a/f1 b/f1
+--- a/f1
++++ b/f1
+@@ -1,3 +1,3 @@
+-A
++X
+ 1
+-B
++Y
+EOF
+
+cat <<EOF >expected.f1.0.2 || exit 1
+diff --git a/f1 b/f1
+--- a/f1
++++ b/f1
+@@ -1 +1 @@
+-A
++X
+@@ -3 +3 @@ A
+-B
++Y
+EOF
+
+# common lines	ctx	intrctx	hunks
+t 1 line	0		2
+t 1 line	0	0	2
+t 1 line	0	1	1
+t 1 line	0	2	1
+t 1 line	1		1
+
+t 2 lines	0		2
+t 2 lines	0	0	2
+t 2 lines	0	1	2
+t 2 lines	0	2	1
+t 2 lines	1		1
+
+t 3 lines	1		2
+t 3 lines	1	0	2
+t 3 lines	1	1	1
+t 3 lines	1	2	1
+
+t 9 lines	3		2
+t 9 lines	3	2	2
+t 9 lines	3	3	1
+
+test_done
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index 84fff583e..361f80231 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -84,6 +84,7 @@ typedef long (*find_func_t)(const char *line, long line_len, char *buffer, long
 
 typedef struct s_xdemitconf {
 	long ctxlen;
+	long interhunkctxlen;
 	unsigned long flags;
 	find_func_t find_func;
 	void *find_func_priv;
diff --git a/xdiff/xemit.c b/xdiff/xemit.c
index 4625c1b42..05bfa41f1 100644
--- a/xdiff/xemit.c
+++ b/xdiff/xemit.c
@@ -59,9 +59,10 @@ static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *
  */
 xdchange_t *xdl_get_hunk(xdchange_t *xscr, xdemitconf_t const *xecfg) {
 	xdchange_t *xch, *xchp;
+	long max_common = 2 * xecfg->ctxlen + xecfg->interhunkctxlen;
 
 	for (xchp = xscr, xch = xscr->next; xch; xchp = xch, xch = xch->next)
-		if (xch->i1 - (xchp->i1 + xchp->chg1) > 2 * xecfg->ctxlen)
+		if (xch->i1 - (xchp->i1 + xchp->chg1) > max_common)
 			break;
 
 	return xchp;