patch 8.2.3788: lambda for option that is a function may be freed
Problem: Lambda for option that is a function may be garbage collected.
Solution: Set a reference in the funcref. (Yegappan Lakshmanan,
closes #9330)
diff --git a/src/proto/eval.pro b/src/proto/eval.pro
index 45b559d..dc9c53b 100644
--- a/src/proto/eval.pro
+++ b/src/proto/eval.pro
@@ -52,6 +52,7 @@
int set_ref_in_dict(dict_T *d, int copyID);
int set_ref_in_list(list_T *ll, int copyID);
int set_ref_in_list_items(list_T *l, int copyID, ht_stack_T **ht_stack);
+int set_ref_in_callback(callback_T *cb, int copyID);
int set_ref_in_item(typval_T *tv, int copyID, ht_stack_T **ht_stack, list_stack_T **list_stack);
char_u *echo_string_core(typval_T *tv, char_u **tofree, char_u *numbuf, int copyID, int echo_style, int restore_copyID, int composite_val);
char_u *echo_string(typval_T *tv, char_u **tofree, char_u *numbuf, int copyID);