patch 9.0.0632: calling a function from an "expr" option has overhead
Problem: Calling a function from an "expr" option has too much overhead.
Solution: Add call_simple_func() and use it for 'foldexpr'
diff --git a/src/proto/userfunc.pro b/src/proto/userfunc.pro
index f509523..ee17049 100644
--- a/src/proto/userfunc.pro
+++ b/src/proto/userfunc.pro
@@ -36,8 +36,9 @@
int get_callback_depth(void);
int call_callback(callback_T *callback, int len, typval_T *rettv, int argcount, typval_T *argvars);
varnumber_T call_callback_retnr(callback_T *callback, int argcount, typval_T *argvars);
-void user_func_error(int error, char_u *name, funcexe_T *funcexe);
+void user_func_error(int error, char_u *name, int found_var);
int call_func(char_u *funcname, int len, typval_T *rettv, int argcount_in, typval_T *argvars_in, funcexe_T *funcexe);
+int call_simple_func(char_u *funcname, int len, typval_T *rettv);
char_u *printable_func_name(ufunc_T *fp);
char_u *trans_function_name(char_u **pp, int *is_global, int skip, int flags, funcdict_T *fdp, partial_T **partial, type_T **type);
char_u *get_scriptlocal_funcname(char_u *funcname);