| A parameter type is missing a lifetime constraint or has a lifetime that |
| does not live long enough. |
| |
| Erroneous code example: |
| |
| ```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 |
| } |
| ``` |
| |
| Type parameters in type definitions have lifetimes associated with them that |
| represent how long the data stored within them is guaranteed to 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. |
| |
| This will compile, because it has the constraint on the type parameter: |
| |
| ``` |
| struct Foo<T: 'static> { |
| foo: &'static T |
| } |
| ``` |
