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+#### Note: this error code is no longer emitted by the compiler.
+
+In Rust 1.3, the default object lifetime bounds are expected to change, as
+described in [RFC 1156]. You are getting a warning because the compiler
+thinks it is possible that this change will cause a compilation error in your
+code. It is possible, though unlikely, that this is a false alarm.
+
+The heart of the change is that where `&'a Box<SomeTrait>` used to default to
+`&'a Box<SomeTrait+'a>`, it now defaults to `&'a Box<SomeTrait+'static>` (here,
+`SomeTrait` is the name of some trait type). Note that the only types which are
+affected are references to boxes, like `&Box<SomeTrait>` or
+`&[Box<SomeTrait>]`. More common types like `&SomeTrait` or `Box<SomeTrait>`
+are unaffected.
+
+To silence this warning, edit your code to use an explicit bound. Most of the
+time, this means that you will want to change the signature of a function that
+you are calling. For example, if the error is reported on a call like `foo(x)`,
+and `foo` is defined as follows:
+
+```
+# trait SomeTrait {}
+fn foo(arg: &Box<SomeTrait>) { /* ... */ }
+```
+
+You might change it to:
+
+```
+# trait SomeTrait {}
+fn foo<'a>(arg: &'a Box<SomeTrait+'a>) { /* ... */ }
+```
+
+This explicitly states that you expect the trait object `SomeTrait` to contain
+references (with a maximum lifetime of `'a`).
+
+[RFC 1156]: https://github.com/rust-lang/rfcs/blob/master/text/1156-adjust-default-object-bounds.md