patch 8.1.0935: old regexp engine may use invalid buffer
Problem: Old regexp engine may use invalid buffer for 'iskeyword' or
uninitialized buffer pointer. (Kuang-che Wu)
Solution: Set rex.reg_buf when compiling the pattern. (closes #3972)
diff --git a/src/regexp.c b/src/regexp.c
index 30a604b..8362048 100644
--- a/src/regexp.c
+++ b/src/regexp.c
@@ -7998,6 +7998,8 @@
bt_regengine.expr = expr;
nfa_regengine.expr = expr;
#endif
+ // reg_iswordc() uses rex.reg_buf
+ rex.reg_buf = curbuf;
/*
* First try the NFA engine, unless backtracking was requested.