apply: allow rerere() to work on --3way results

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

builtin/apply.c

@@ -18,6 +18,7 @@
 #include "parse-options.h"
 #include "xdiff-interface.h"
 #include "ll-merge.h"
+#include "rerere.h"
 
 /*
  *  --check turns on checking that the working tree matches the
@@ -4026,6 +4027,8 @@ static int write_out_results(struct patch *list)
 		for_each_string_list_item(item, &cpath)
 			fprintf(stderr, "U %s\n", item->string);
 		string_list_clear(&cpath, 0);
+
+		rerere(0);
 	}
 
 	return errs;

t/t4108-apply-threeway.sh

@@ -75,4 +75,29 @@ test_expect_success 'apply with --3way' '
 	test_cmp expect.diff actual.diff
 '
 
+test_expect_success 'apply with --3way with rerere enabled' '
+	git config rerere.enabled true &&
+
+	# Merging side should be similar to applying this patch
+	git diff ...side >P.diff &&
+
+	# The corresponding conflicted merge
+	git reset --hard &&
+	git checkout master^0 &&
+	test_must_fail git merge --no-commit side &&
+
+	# Manually resolve and record the resolution
+	create_file 1 two 3 4 five six 7 >one &&
+	git rerere &&
+	cat one >expect &&
+
+	# should fail to apply
+	git reset --hard &&
+	git checkout master^0 &&
+	test_must_fail git apply --index --3way P.diff &&
+
+	# but rerere should have replayed the recorded resolution
+	test_cmp expect one
+'
+
 test_done