[Bug c++/60460] warn_unused_result doesn't warn on unused result when std::pair return type

[mdennis at merfer dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60460

--- Comment #1 from Matthew Dennis <mdennis at merfer dot net> ---
Created attachment 32308
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32308&action=edit
reproduction of warn_unused_result problem