commit https://github.com/vim/vim/commit/1d90a5a5af84250e226f8a9121e771f7b72aa894 Author: Bram Moolenaar <Bram@vim.org> Date: Fri Jul 1 11:59:47 2016 +0200 patch 7.4.1968 Problem: Invalid memory access with "\<C-">. Solution: Do not recognize this as a special character. (Dominique Pelle)

--- a/src/testdir/test_expr.vim
+++ b/src/testdir/test_expr.vim
@@ -101,3 +101,8 @@ endfunc
 func Test_set_reg_null_list()
   call setreg('x', test_null_list())
 endfunc
+
+func Test_special_char()
+  " The failure is only visible using valgrind.
+  call assert_fails('echo "\<C-">')
+endfunc