diff-files: show unmerged entries correctly

Earlier, e9c8409 (diff-index --cached --raw: show tree entry on the LHS
for unmerged entries., 2007-01-05) taught the command to show the object
name and the mode from the entry coming from the tree side when comparing
a tree with an unmerged index.

This is a belated companion patch that teaches diff-files to show the mode
from the entry coming from the working tree side, when comparing an
unmerged index and the working tree.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff-lib.c

@@ -111,6 +111,8 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 
 		if (ce_stage(ce)) {
 			struct combine_diff_path *dpath;
+			struct diff_filepair *pair;
+			unsigned int wt_mode = 0;
 			int num_compare_stages = 0;
 			size_t path_len;
 
@@ -129,7 +131,7 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 
 			changed = check_removed(ce, &st);
 			if (!changed)
-				dpath->mode = ce_mode_from_stat(ce, st.st_mode);
+				wt_mode = ce_mode_from_stat(ce, st.st_mode);
 			else {
 				if (changed < 0) {
 					perror(ce->name);
@@ -137,7 +139,9 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 				}
 				if (silent_on_removed)
 					continue;
+				wt_mode = 0;
 			}
+			dpath->mode = wt_mode;
 
 			while (i < entries) {
 				struct cache_entry *nce = active_cache[i];
@@ -183,7 +187,9 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 			 * Show the diff for the 'ce' if we found the one
 			 * from the desired stage.
 			 */
-			diff_unmerge(&revs->diffopt, ce->name);
+			pair = diff_unmerge(&revs->diffopt, ce->name);
+			if (wt_mode)
+				pair->two->mode = wt_mode;
 			if (ce_stage(ce) != diff_unmerged_stage)
 				continue;
 		}

t/t4046-diff-unmerged.sh

@@ -0,0 +1,87 @@
+#!/bin/sh
+
+test_description='diff with unmerged index entries'
+. ./test-lib.sh
+
+test_expect_success setup '
+	for i in 0 1 2 3
+	do
+		blob=$(echo $i | git hash-object --stdin) &&
+		eval "blob$i=$blob" &&
+		eval "m$i=\"100644 \$blob$i $i\"" || break
+	done &&
+	paths= &&
+	for b in o x
+	do
+		for o in o x
+		do
+			for t in o x
+			do
+				path="$b$o$t" &&
+				case "$path" in ooo) continue ;; esac
+				paths="$paths$path " &&
+				p="	$path" &&
+				case "$b" in x) echo "$m1$p" ;; esac &&
+				case "$o" in x) echo "$m2$p" ;; esac &&
+				case "$t" in x) echo "$m3$p" ;; esac ||
+				break
+			done || break
+		done || break
+	done >ls-files-s.expect &&
+	git update-index --index-info <ls-files-s.expect &&
+	git ls-files -s >ls-files-s.actual &&
+	test_cmp ls-files-s.expect ls-files-s.actual
+'
+
+test_expect_success 'diff-files -0' '
+	for path in $paths
+	do
+		>"$path" &&
+		echo ":000000 100644 $_z40 $_z40 U	$path"
+	done >diff-files-0.expect &&
+	git diff-files -0 >diff-files-0.actual &&
+	test_cmp diff-files-0.expect diff-files-0.actual
+'
+
+test_expect_success 'diff-files -1' '
+	for path in $paths
+	do
+		>"$path" &&
+		echo ":000000 100644 $_z40 $_z40 U	$path" &&
+		case "$path" in
+		x??) echo ":100644 100644 $blob1 $_z40 M	$path"
+		esac
+	done >diff-files-1.expect &&
+	git diff-files -1 >diff-files-1.actual &&
+	test_cmp diff-files-1.expect diff-files-1.actual
+'
+
+test_expect_success 'diff-files -2' '
+	for path in $paths
+	do
+		>"$path" &&
+		echo ":000000 100644 $_z40 $_z40 U	$path" &&
+		case "$path" in
+		?x?) echo ":100644 100644 $blob2 $_z40 M	$path"
+		esac
+	done >diff-files-2.expect &&
+	git diff-files -2 >diff-files-2.actual &&
+	test_cmp diff-files-2.expect diff-files-2.actual &&
+	git diff-files >diff-files-default-2.actual &&
+	test_cmp diff-files-2.expect diff-files-default-2.actual
+'
+
+test_expect_success 'diff-files -3' '
+	for path in $paths
+	do
+		>"$path" &&
+		echo ":000000 100644 $_z40 $_z40 U	$path" &&
+		case "$path" in
+		??x) echo ":100644 100644 $blob3 $_z40 M	$path"
+		esac
+	done >diff-files-3.expect &&
+	git diff-files -3 >diff-files-3.actual &&
+	test_cmp diff-files-3.expect diff-files-3.actual
+'
+
+test_done