I've added a test for the second example mentioned in #5239. The first example does not compile with a reasonable error message. Should I add a compile-fail test for that example as well?
/rust/src/test/run-pass/issue-5239.rs:15:45: 15:51 error: binary operation + cannot be applied to type `&int`
rust/src/test/run-pass/issue-5239.rs:15 let _f = |ref x: int| { x += 1};
^~~~~~
error: aborting due to previous error
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