patch 7.4.2244
Problem:    Adding pattern to ":oldfiles" is not a generic solution.
Solution:   Add the ":filter /pat/ cmd" command modifier.  Only works for some
            commands right now.
diff --git a/src/structs.h b/src/structs.h
index f918442..1dfe131 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -571,6 +571,7 @@
 # ifdef FEAT_AUTOCMD
     char_u	*save_ei;		/* saved value of 'eventignore' */
 # endif
+    regmatch_T	filter_regmatch;	/* set by :filter /pat/ */
 } cmdmod_T;
 
 #define MF_SEED_LEN	8