[][src]Struct rustc::middle::region::ScopeTree

pub struct ScopeTree {
    root_body: Option<HirId>,
    root_parent: Option<HirId>,
    parent_map: FxHashMap<Scope, (Scope, ScopeDepth)>,
    var_map: FxHashMap<ItemLocalId, Scope>,
    destruction_scopes: FxHashMap<ItemLocalId, Scope>,
    rvalue_scopes: FxHashMap<ItemLocalId, Option<Scope>>,
    closure_tree: FxHashMap<ItemLocalId, ItemLocalId>,
    yield_in_scope: FxHashMap<Scope, YieldData>,
    body_expr_count: FxHashMap<BodyId, usize>,
}
⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

The region scope tree encodes information about region relationships.

Fields

root_body: Option<HirId>
⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

If not empty, this body is the root of this region hierarchy.

root_parent: Option<HirId>
⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

The parent of the root body owner, if the latter is an an associated const or method, as impls/traits can also have lifetime parameters free in this body.

parent_map: FxHashMap<Scope, (Scope, ScopeDepth)>
⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Maps from a scope ID to the enclosing scope id; this is usually corresponding to the lexical nesting, though in the case of closures the parent scope is the innermost conditional expression or repeating block. (Note that the enclosing scope ID for the block associated with a closure is the closure itself.)

var_map: FxHashMap<ItemLocalId, Scope>
⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Maps from a variable or binding ID to the block in which that variable is declared.

destruction_scopes: FxHashMap<ItemLocalId, Scope>
⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Maps from a NodeId to the associated destruction scope (if any).

rvalue_scopes: FxHashMap<ItemLocalId, Option<Scope>>
⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

rvalue_scopes includes entries for those expressions whose cleanup scope is larger than the default. The map goes from the expression ID to the cleanup scope id. For rvalues not present in this table, the appropriate cleanup scope is the innermost enclosing statement, conditional expression, or repeating block (see terminating_scopes). In constants, None is used to indicate that certain expressions escape into 'static and should have no local cleanup scope.

closure_tree: FxHashMap<ItemLocalId, ItemLocalId>
⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Encodes the hierarchy of fn bodies. Every fn body (including closures) forms its own distinct region hierarchy, rooted in the block that is the fn body. This map points from the ID of that root block to the ID of the root block for the enclosing fn, if any. Thus the map structures the fn bodies into a hierarchy based on their lexical mapping. This is used to handle the relationships between regions in a fn and in a closure defined by that fn. See the "Modeling closures" section of the README in infer::region_constraints for more details.

yield_in_scope: FxHashMap<Scope, YieldData>
⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

If there are any yield nested within a scope, this map stores the Span of the last one and its index in the postorder of the Visitor traversal on the HIR.

HIR Visitor postorder indexes might seem like a peculiar thing to care about. but it turns out that HIR bindings and the temporary results of HIR expressions are never storage-live at the end of HIR nodes with postorder indexes lower than theirs, and therefore don't need to be suspended at yield-points at these indexes.

For an example, suppose we have some code such as:

This example is not tested
    foo(f(), yield y, bar(g()))

With the HIR tree (calls numbered for expository purposes)

    Call#0(foo, [Call#1(f), Yield(y), Call#2(bar, Call#3(g))])

Obviously, the result of f() was created before the yield (and therefore needs to be kept valid over the yield) while the result of g() occurs after the yield (and therefore doesn't). If we want to infer that, we can look at the postorder traversal:

    `foo` `f` Call#1 `y` Yield `bar` `g` Call#3 Call#2 Call#0

In which we can easily see that Call#1 occurs before the yield, and Call#3 after it.

To see that this method works, consider:

Let D be our binding/temporary and U be our other HIR node, with HIR-postorder(U) < HIR-postorder(D) (in our example, U would be the yield and D would be one of the calls). Let's show that D is storage-dead at U.

Remember that storage-live/storage-dead refers to the state of the storage, and does not consider moves/drop flags.

Then: 1. From the ordering guarantee of HIR visitors (see rustc::hir::intravisit), D does not dominate U. 2. Therefore, D is potentially storage-dead at U (because we might visit U without ever getting to D). 3. However, we guarantee that at each HIR point, each binding/temporary is always either always storage-live or always storage-dead. This is what is being guaranteed by terminating_scopes including all blocks where the count of executions is not guaranteed. 4. By 2. and 3., D is statically storage-dead at U, QED.

This property ought to not on (3) in an essential way -- it is probably still correct even if we have "unrestricted" terminating scopes. However, why use the complicated proof when a simple one works?

A subtle thing: box expressions, such as box (&x, yield 2, &y). It might seem that a box expression creates a Box<T> temporary when it starts executing, at HIR-preorder(BOX-EXPR). That might be true in the MIR desugaring, but it is not important in the semantics.

The reason is that semantically, until the box expression returns, the values are still owned by their containing expressions. So we'll see that &x.

body_expr_count: FxHashMap<BodyId, usize>
⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

The number of visit_expr and visit_pat calls done in the body. Used to sanity check visit_expr/visit_pat call count when calculating generator interiors.

Methods

impl<'tcx> ScopeTree[src]

pub fn record_scope_parent(
    &mut self,
    child: Scope,
    parent: Option<(Scope, ScopeDepth)>
)
[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

pub fn each_encl_scope<E>(&self, e: E) where
    E: FnMut(Scope, Scope), 
[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

pub fn each_var_scope<E>(&self, e: E) where
    E: FnMut(&ItemLocalId, Scope), 
[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

pub fn opt_destruction_scope(&self, n: ItemLocalId) -> Option<Scope>[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

fn record_closure_parent(
    &mut self,
    sub_closure: ItemLocalId,
    sup_closure: ItemLocalId
)
[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Records that sub_closure is defined within sup_closure. These IDs should be the ID of the block that is the fn body, which is also the root of the region hierarchy for that fn.

fn record_var_scope(&mut self, var: ItemLocalId, lifetime: Scope)[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

fn record_rvalue_scope(&mut self, var: ItemLocalId, lifetime: Option<Scope>)[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

pub fn opt_encl_scope(&self, id: Scope) -> Option<Scope>[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Returns the narrowest scope that encloses id, if any.

pub fn encl_scope(&self, id: Scope) -> Scope[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Returns the narrowest scope that encloses id, if any.

pub fn var_scope(&self, var_id: ItemLocalId) -> Scope[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Returns the lifetime of the local variable var_id

pub fn temporary_scope(&self, expr_id: ItemLocalId) -> Option<Scope>[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Returns the scope when the temp created by expr_id will be cleaned up.

pub fn var_region(&self, id: ItemLocalId) -> RegionKind[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Returns the lifetime of the variable id.

pub fn scopes_intersect(&self, scope1: Scope, scope2: Scope) -> bool[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

pub fn is_subscope_of(&self, subscope: Scope, superscope: Scope) -> bool[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Returns true if subscope is equal to or is lexically nested inside superscope, and false otherwise.

pub fn containing_body(&self, scope: Scope) -> Option<ItemLocalId>[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Returns the ID of the innermost containing body.

pub fn nearest_common_ancestor(&self, scope_a: Scope, scope_b: Scope) -> Scope[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Finds the nearest common ancestor of two scopes. That is, finds the smallest scope which is greater than or equal to both scope_a and scope_b.

pub fn early_free_scope(
    &self,
    tcx: TyCtxt<'tcx>,
    br: &EarlyBoundRegion
) -> Scope
[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Assuming that the provided region was defined within this ScopeTree, returns the outermost Scope that the region outlives.

pub fn free_scope(&self, tcx: TyCtxt<'tcx>, fr: &FreeRegion) -> Scope[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Assuming that the provided region was defined within this ScopeTree, returns the outermost Scope that the region outlives.

pub fn yield_in_scope(&self, scope: Scope) -> Option<YieldData>[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Checks whether the given scope contains a yield. If so, returns Some((span, expr_count)) with the span of a yield we found and the number of expressions and patterns appearing before the yield in the body + 1. If there a are multiple yields in a scope, the one with the highest number is returned.

pub fn yield_in_scope_for_expr(
    &self,
    scope: Scope,
    expr_hir_id: HirId,
    body: &'tcx Body
) -> Option<Span>
[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Checks whether the given scope contains a yield and if that yield could execute after expr. If so, it returns the span of that yield. scope must be inside the body.

pub fn body_expr_count(&self, body_id: BodyId) -> Option<usize>[src]

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

Gives the number of expressions visited in a body. Used to sanity check visit_expr call count when calculating generator interiors.

Trait Implementations

impl ArenaAllocatable for ScopeTree[src]

impl<'tcx> ArenaField<'tcx> for ScopeTree[src]

impl Default for ScopeTree[src]

impl Debug for ScopeTree[src]

impl<'a> HashStable<StableHashingContext<'a>> for ScopeTree[src]

Auto Trait Implementations

impl !Send for ScopeTree

impl !Sync for ScopeTree

impl Unpin for ScopeTree

impl UnwindSafe for ScopeTree

impl RefUnwindSafe for ScopeTree

Blanket Implementations

impl<T> ArenaAllocatable for T where
    T: Copy
[src]

impl<T> MaybeResult<T> for T[src]

type Error = !

⚙️ This is an internal compiler API. (rustc_private)

This crate is being loaded from the sysroot, a permanently unstable location for private compiler dependencies. It is not intended for general use. Prefer using a public version of this crate from crates.io via Cargo.toml.

impl<'a, T> Captures<'a> for T where
    T: ?Sized
[src]

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

impl<T> From<T> for T[src]

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

impl<T> Borrow<T> for T where
    T: ?Sized
[src]

impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

impl<T> Any for T where
    T: 'static + ?Sized
[src]

impl<T> Erased for T[src]

impl<E> SpecializationError for E[src]