updated for version 7.3.1243
Problem:    New regexp engine: back references in look-behind match don't
            work. (Lech Lorens)
Solution:   Copy the submatches before a recursive match.
diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index 01bc065..cba4001 100644
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -290,10 +290,11 @@
 #endif
 static int *re2post __ARGS((void));
 static nfa_state_T *alloc_state __ARGS((int c, nfa_state_T *out, nfa_state_T *out1));
+static void st_error __ARGS((int *postfix, int *end, int *p));
+static int nfa_max_width __ARGS((nfa_state_T *startstate, int depth));
 static nfa_state_T *post2nfa __ARGS((int *postfix, int *end, int nfa_calc_size));
 static void nfa_postprocess __ARGS((nfa_regprog_T *prog));
 static int check_char_class __ARGS((int class, int c));
-static void st_error __ARGS((int *postfix, int *end, int *p));
 static void nfa_save_listids __ARGS((nfa_regprog_T *prog, int *list));
 static void nfa_restore_listids __ARGS((nfa_regprog_T *prog, int *list));
 static int nfa_re_num_cmp __ARGS((long_u val, int op, long_u pos));
@@ -3469,6 +3470,7 @@
 #ifdef ENABLE_LOG
 static void log_subsexpr __ARGS((regsubs_T *subs));
 static void log_subexpr __ARGS((regsub_T *sub));
+static char *pim_info __ARGS((nfa_pim_T *pim));
 
     static void
 log_subsexpr(subs)
@@ -3508,7 +3510,8 @@
 }
 
     static char *
-pim_info(nfa_pim_T *pim)
+pim_info(pim)
+    nfa_pim_T *pim;
 {
     static char buf[30];
 
@@ -3532,6 +3535,7 @@
 static void copy_sub __ARGS((regsub_T *to, regsub_T *from));
 static void copy_sub_off __ARGS((regsub_T *to, regsub_T *from));
 static int sub_equal __ARGS((regsub_T *sub1, regsub_T *sub2));
+static int match_backref __ARGS((regsub_T *sub, int subidx, int *bytelen));
 static int has_state_with_pos __ARGS((nfa_list_T *l, nfa_state_T *state, regsubs_T *subs));
 static int state_in_list __ARGS((nfa_list_T *l, nfa_state_T *state, regsubs_T *subs));
 static void addstate __ARGS((nfa_list_T *l, nfa_state_T *state, regsubs_T *subs, nfa_pim_T *pim, int off));
@@ -4319,8 +4323,6 @@
     return FAIL;
 }
 
-static int match_backref __ARGS((regsub_T *sub, int subidx, int *bytelen));
-
 /*
  * Check for a match with subexpression "subidx".
  * Return TRUE if it matches.
@@ -5195,6 +5197,10 @@
 			 || t->state->c == NFA_START_INVISIBLE_BEFORE_FIRST
 			 || t->state->c == NFA_START_INVISIBLE_BEFORE_NEG_FIRST)
 		    {
+			/* Copy submatch info for the recursive call, so that
+			 * \1 can be matched. */
+			copy_sub_off(&m->norm, &t->subs.norm);
+
 			/*
 			 * First try matching the invisible match, then what
 			 * follows.