patch 8.2.3911: Vim9: type check for filter() does not accept unknown Commit: https://github.com/vim/vim/commit/ef8f04b1d1daf2e0be8fa38dedcae84ebfc5ffb4 Author: Bram Moolenaar <Bram@vim.org> Date: Mon Dec 27 12:29:19 2021 +0000 patch 8.2.3911: Vim9: type check for filter() does not accept unknown Problem: Vim9: type check for filter() does not accept unknown. Solution: Also accept unknown for the return type. (closes https://github.com/vim/vim/issues/9413)

/* bufwrite.c */
char *new_file_message(void);
int buf_write(buf_T *buf, char_u *fname, char_u *sfname, linenr_T start, linenr_T end, exarg_T *eap, int append, int forceit, int reset_changed, int filtering);
/* vim: set ft=c : */