| Types in type definitions have lifetimes associated with them that represent |
| how long the data stored within them is guaranteed to be live. This lifetime |
| must be as long as the data needs to be alive, and missing the constraint that |
| denotes this will cause this error. |
| |
| ```compile_fail,E0310 |
| // This won't compile because T is not constrained to the static lifetime |
| // the reference needs |
| struct Foo<T> { |
| foo: &'static T |
| } |
| ``` |
| |
| This will compile, because it has the constraint on the type parameter: |
| |
| ``` |
| struct Foo<T: 'static> { |
| foo: &'static T |
| } |
| ``` |
