patch 8.2.2121: internal error when using \ze before \zs in a patternv8.2.2121

Problem:    Internal error when using \ze before \zs in a pattern.
Solution:   Check the end is never before the start. (closes #7442)

1 files changed, 17 insertions, 0 deletions

diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index c75c575fd..da80ee921 100644
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -7225,6 +7225,23 @@ nfa_regexec_both(
 #endif
 
 theend:
+    // Make sure the end is never before the start.  Can happen when \zs and
+    // \ze are used.
+    if (REG_MULTI)
+    {
+	lpos_T *start = &rex.reg_mmatch->startpos[0];
+	lpos_T *end = &rex.reg_mmatch->endpos[0];
+
+	if (end->lnum < start->lnum
+			|| (end->lnum == start->lnum && end->col < start->col))
+	    rex.reg_mmatch->endpos[0] = rex.reg_mmatch->startpos[0];
+    }
+    else
+    {
+	if (rex.reg_match->endp[0] < rex.reg_match->startp[0])
+	    rex.reg_match->endp[0] = rex.reg_match->startp[0];
+    }
+
     return retval;
 }