patch 8.2.4458: Vim9: compiling filter() call fails with unknown arguments Commit: https://github.com/vim/vim/commit/6e1a38745f794715dc624399c318f513b54797c4 Author: Bram Moolenaar <Bram@vim.org> Date: Wed Feb 23 19:11:49 2022 +0000 patch 8.2.4458: Vim9: compiling filter() call fails with unknown arguments Problem: Vim9: compiling filter() call fails with funcref that has unknown arguments. Solution: Do not check the arguments if they are unknown at compile time. (closes #9835)

--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -552,6 +552,8 @@ check_map_filter_arg2(type_T *type, argc
 	    t_func_exp.tt_member = &t_bool;
 	if (args[0] == NULL)
 	    args[0] = &t_unknown;
+	if (type->tt_argcount == -1)
+	    t_func_exp.tt_argcount = -1;
 
 	where.wt_index = 2;
 	return check_type(&t_func_exp, type, TRUE, where);