infer_static_outlives_requirements

The tracking issue for this feature is: #44493

The infer_static_outlives_requirements feature indicates that certain 'static outlives requirements can be inferred by the compiler rather than stating them explicitly.

Note: It is an accompanying feature to infer_outlives_requirements, which must be enabled to infer outlives requirements.

For example, currently generic struct definitions that contain references, require where-clauses of the form T: 'static. By using this feature the outlives predicates will be inferred, although they may still be written explicitly.

struct Foo<U> where U: 'static { // <-- currently required
    bar: Bar<U>
}
struct Bar<T: 'static> {
    x: T,
}

Examples:

#![feature(infer_outlives_requirements)]
#![feature(infer_static_outlives_requirements)]

#[rustc_outlives]
// Implicitly infer U: 'static
struct Foo<U> {
    bar: Bar<U>
}
struct Bar<T: 'static> {
    x: T,
}