Merge branch 'jk/diff-files-assume-unchanged' into maint

"git diff --find-copies-harder" sometimes pretended as if the mode
bits have changed for paths that are marked with assume-unchanged
bit.

* jk/diff-files-assume-unchanged:
  run_diff_files: do not look at uninitialized stat data

diff-lib.c

@@ -97,7 +97,6 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 		diff_unmerged_stage = 2;
 	entries = active_nr;
 	for (i = 0; i < entries; i++) {
-		struct stat st;
 		unsigned int oldmode, newmode;
 		struct cache_entry *ce = active_cache[i];
 		int changed;
@@ -115,6 +114,7 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 			unsigned int wt_mode = 0;
 			int num_compare_stages = 0;
 			size_t path_len;
+			struct stat st;
 
 			path_len = ce_namelen(ce);
 
@@ -195,26 +195,35 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 			continue;
 
 		/* If CE_VALID is set, don't look at workdir for file removal */
-		changed = (ce->ce_flags & CE_VALID) ? 0 : check_removed(ce, &st);
-		if (changed) {
-			if (changed < 0) {
-				perror(ce->name);
+		if (ce->ce_flags & CE_VALID) {
+			changed = 0;
+			newmode = ce->ce_mode;
+		} else {
+			struct stat st;
+
+			changed = check_removed(ce, &st);
+			if (changed) {
+				if (changed < 0) {
+					perror(ce->name);
+					continue;
+				}
+				diff_addremove(&revs->diffopt, '-', ce->ce_mode,
+					       ce->sha1, !is_null_sha1(ce->sha1),
+					       ce->name, 0);
 				continue;
 			}
-			diff_addremove(&revs->diffopt, '-', ce->ce_mode,
-				       ce->sha1, !is_null_sha1(ce->sha1),
-				       ce->name, 0);
-			continue;
+
+			changed = match_stat_with_submodule(&revs->diffopt, ce, &st,
+							    ce_option, &dirty_submodule);
+			newmode = ce_mode_from_stat(ce, st.st_mode);
 		}
-		changed = match_stat_with_submodule(&revs->diffopt, ce, &st,
-						    ce_option, &dirty_submodule);
+
 		if (!changed && !dirty_submodule) {
 			ce_mark_uptodate(ce);
 			if (!DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
 				continue;
 		}
 		oldmode = ce->ce_mode;
-		newmode = ce_mode_from_stat(ce, st.st_mode);
 		diff_change(&revs->diffopt, oldmode, newmode,
 			    ce->sha1, (changed ? null_sha1 : ce->sha1),
 			    !is_null_sha1(ce->sha1), (changed ? 0 : !is_null_sha1(ce->sha1)),

t/t4039-diff-assume-unchanged.sh

@@ -28,4 +28,15 @@ test_expect_success 'diff-files does not examine assume-unchanged entries' '
 	test -z "$(git diff-files -- one)"
 '
 
+test_expect_success POSIXPERM 'find-copies-harder is not confused by mode bits' '
+	echo content >exec &&
+	chmod +x exec &&
+	git add exec &&
+	git commit -m exec &&
+	git update-index --assume-unchanged exec &&
+	>expect &&
+	git diff-files --find-copies-harder -- exec >actual &&
+	test_cmp expect actual
+'
+
 test_done