user-manual: Explain what submodules are good for.

diff --git a/cache.h b/cache.h
index c7e00e7b0528d640af9e70a2d84455e7cf727993..70abbd59bf8d3ca118836605099b0b5dc66a27b7 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -594,6 +594,9 @@ extern char *convert_to_git(const char *path, const char *src, unsigned long *si
 extern char *convert_to_working_tree(const char *path, const char *src, unsigned long *sizep);
 extern void *convert_sha1_file(const char *path, const unsigned char *sha1, unsigned int mode, enum object_type *type, unsigned long *size);
 
+/* diff.c */
+extern int diff_auto_refresh_index;
+
 /* match-trees.c */
 void shift_tree(const unsigned char *, const unsigned char *, unsigned char *, int);