From 9e61dd3148f23163beafc49b29c4d630743c20af Mon Sep 17 00:00:00 2001
From: Eric Abrahamsen <eric@ericabrahamsen.net>
Date: Thu, 4 May 2017 13:08:13 +0800
Subject: [PATCH] Find-grep can only search on plain strings

* lisp/gnus/gnus-search.el (gnus-search-indexed-massage-output): Drop
  any list expression.
---
 lisp/gnus/gnus-search.el | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lisp/gnus/gnus-search.el b/lisp/gnus/gnus-search.el
index 877ff11c178..fcbb2326978 100644
--- a/lisp/gnus/gnus-search.el
+++ b/lisp/gnus/gnus-search.el
@@ -1888,6 +1888,11 @@ Assume \"size\" key is equal to \"larger\"."
 
 ;;; Find-grep interface
 
+(cl-defmethod gnus-search-transform-expression ((_engine gnus-search-find-grep)
+						(_ list))
+  ;; Drop everything that isn't a plain string.
+  nil)
+
 (cl-defmethod gnus-search-run-search ((engine gnus-search-find-grep)
 				      server query
 				      &optional groups)
-- 
2.39.5