Enum rustc_resolve::late::lifetimes::Scope

pub(in late::lifetimes) enum Scope<'a> {
    Binder {
        lifetimes: FxHashMap<ParamName, Region>,
        next_early_index: u32,
        track_lifetime_uses: bool,
        opaque_type_parent: bool,
        s: &'a Scope<'a>,
    },
    Body {
        id: BodyId,
        s: &'a Scope<'a>,
    },
    Elision {
        elide: Elide,
        s: &'a Scope<'a>,
    },
    ObjectLifetimeDefault {
        lifetime: Option<Region>,
        s: &'a Scope<'a>,
    },
    Root,
}

Variants

Binder

Declares lifetimes, and each can be early-bound or late-bound. The DebruijnIndex of late-bound lifetimes starts at 1 and it should be shifted by the number of Binders in between the declaration Binder and the location it's referenced from.

Fields of Binder

lifetimes: FxHashMap<ParamName, Region>next_early_index: u32

if we extend this scope with another scope, what is the next index we should use for an early-bound region?

track_lifetime_uses: bool

Flag is set to true if, in this binder, '_ would be equivalent to a "single-use region". This is true on impls, but not other kinds of items.

opaque_type_parent: bool

Whether or not this binder would serve as the parent binder for opaque types introduced within. For example:

    fn foo<'a>() -> impl for<'b> Trait<Item = impl Trait2<'a>>

Here, the opaque types we create for the impl Trait and impl Trait2 references will both have the foo item as their parent. When we get to impl Trait2, we find that it is nested within the for<> binder -- this flag allows us to skip that when looking for the parent binder of the resulting opaque type.

s: &'a Scope<'a>

Body

Lifetimes introduced by a fn are scoped to the call-site for that fn, if this is a fn body, otherwise the original definitions are used. Unspecified lifetimes are inferred, unless an elision scope is nested, e.g., (&T, fn(&T) -> &T); becomes (&'_ T, for<'a> fn(&'a T) -> &'a T).

Fields of Body

id: BodyIds: &'a Scope<'a>

Elision

A scope which either determines unspecified lifetimes or errors on them (e.g., due to ambiguity). For more details, see Elide.

Fields of Elision

elide: Elides: &'a Scope<'a>

ObjectLifetimeDefault

Use a specific lifetime (if Some) or leave it unset (to be inferred in a function body or potentially error outside one), for the default choice of lifetime in a trait object type.

Fields of ObjectLifetimeDefault

lifetime: Option<Region>s: &'a Scope<'a>

Root

Trait Implementations

impl<'a> Debug for Scope<'a>

pub fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.