patch 8.0.0643: when a pattern search is slow Vim becomes unusable commit https://github.com/vim/vim/commit/fbd0b0af6800f6ff89857863d6a07ea03f09ff6c Author: Bram Moolenaar <Bram@vim.org> Date: Sat Jun 17 18:44:21 2017 +0200 patch 8.0.0643: when a pattern search is slow Vim becomes unusable Problem: When 'hlsearch' is set and matching with the last search pattern is very slow, Vim becomes unusable. Cannot quit search by pressing CTRL-C. Solution: When the search times out set a flag and don't try again. Check for timeout and CTRL-C in NFA loop that adds states.

--- a/src/regexp.h
+++ b/src/regexp.h
@@ -165,8 +165,8 @@ struct regengine
 {
     regprog_T	*(*regcomp)(char_u*, int);
     void	(*regfree)(regprog_T *);
-    int		(*regexec_nl)(regmatch_T*, char_u*, colnr_T, int);
-    long	(*regexec_multi)(regmmatch_T*, win_T*, buf_T*, linenr_T, colnr_T, proftime_T*);
+    int		(*regexec_nl)(regmatch_T *, char_u *, colnr_T, int);
+    long	(*regexec_multi)(regmmatch_T *, win_T *, buf_T *, linenr_T, colnr_T, proftime_T *, int *);
     char_u	*expr;
 };