[rustc.git] / src / librustc_error_codes / error_codes / E0310.md

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
}
```
Commit	Line	Data
74b04a01 XL	1	A parameter type is missing a lifetime constraint or has a lifetime that
	2	does not live long enough.
	3
	4	Erroneous code example:
60c5eb7d XL	5
	6	```compile_fail,E0310
	7	// This won't compile because T is not constrained to the static lifetime
	8	// the reference needs
	9	struct Foo<T> {
	10	foo: &'static T
	11	}
	12	```
	13
74b04a01 XL	14	Type parameters in type definitions have lifetimes associated with them that
	15	represent how long the data stored within them is guaranteed to live. This
	16	lifetime must be as long as the data needs to be alive, and missing the
	17	constraint that denotes this will cause this error.
	18
60c5eb7d XL	19	This will compile, because it has the constraint on the type parameter:
	20
	21	```
	22	struct Foo<T: 'static> {
	23	foo: &'static T
	24	}
	25	```