patch 8.1.0098: segfault when pattern with z() is very slow commit https://github.com/vim/vim/commit/bcf9442307075bac40d44328c8bf7ea21857b138 Author: Bram Moolenaar <Bram@vim.org> Date: Sat Jun 23 14:21:42 2018 +0200 patch 8.1.0098: segfault when pattern with \z() is very slow Problem: Segfault when pattern with \z() is very slow. Solution: Check for NULL regprog. Add "nfa_fail" to test_override() to be able to test this. Fix that 'searchhl' resets called_emsg.

--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -13090,10 +13090,13 @@ f_test_override(typval_T *argvars, typva
 		save_starting = -1;
 	    }
 	}
+	else if (STRCMP(name, (char_u *)"nfa_fail") == 0)
+	    nfa_fail_for_testing = val;
 	else if (STRCMP(name, (char_u *)"ALL") == 0)
 	{
 	    disable_char_avail_for_testing = FALSE;
 	    disable_redraw_for_testing = FALSE;
+	    nfa_fail_for_testing = FALSE;
 	    if (save_starting >= 0)
 	    {
 		starting = save_starting;