Struct rustc_middle::middle::region::Scope

pub struct Scope {
    pub id: ItemLocalId,
    pub data: ScopeData,
}

Represents a statically-describable scope that can be used to bound the lifetime/region for values.

Node(node_id): Any AST node that has any scope at all has the Node(node_id) scope. Other variants represent special cases not immediately derivable from the abstract syntax tree structure.

DestructionScope(node_id) represents the scope of destructors implicitly-attached to node_id that run immediately after the expression for node_id itself. Not every AST node carries a DestructionScope, but those that are terminating_scopes do; see discussion with ScopeTree.

Remainder { block, statement_index } represents the scope of user code running immediately after the initializer expression for the indexed statement, until the end of the block.

So: the following code can be broken down into the scopes beneath:

let a = f().g( 'b: { let x = d(); let y = d(); x.h(y)  }   ) ;

                                                             +-+ (D12.)
                                                       +-+       (D11.)
                                             +---------+         (R10.)
                                             +-+                  (D9.)
                                  +----------+                    (M8.)
                                +----------------------+          (R7.)
                                +-+                               (D6.)
                     +----------+                                 (M5.)
                   +-----------------------------------+          (M4.)
        +--------------------------------------------------+      (M3.)
        +--+                                                      (M2.)
+-----------------------------------------------------------+     (M1.)

 (M1.): Node scope of the whole `let a = ...;` statement.
 (M2.): Node scope of the `f()` expression.
 (M3.): Node scope of the `f().g(..)` expression.
 (M4.): Node scope of the block labeled `'b:`.
 (M5.): Node scope of the `let x = d();` statement
 (D6.): DestructionScope for temporaries created during M5.
 (R7.): Remainder scope for block `'b:`, stmt 0 (let x = ...).
 (M8.): Node scope of the `let y = d();` statement.
 (D9.): DestructionScope for temporaries created during M8.
(R10.): Remainder scope for block `'b:`, stmt 1 (let y = ...).
(D11.): DestructionScope for temporaries and bindings from block `'b:`.
(D12.): DestructionScope for temporaries created during M1 (e.g., f()).

Note that while the above picture shows the destruction scopes as following their corresponding node scopes, in the internal data structures of the compiler the destruction scopes are represented as enclosing parents. This is sound because we use the enclosing parent relationship just to ensure that referenced values live long enough; phrased another way, the starting point of each range is not really the important thing in the above picture, but rather the ending point.

Fields

id: ItemLocalId

data: ScopeData

Implementations

impl Scope

pub fn item_local_id(&self) -> ItemLocalId

Returns an item-local ID associated with this scope.

N.B., likely to be replaced as API is refined; e.g., pnkfelix anticipates fn entry_node_id and fn each_exit_node_id.

pub fn hir_id(&self, scope_tree: &ScopeTree) -> Option<HirId>

pub fn span(&self, tcx: TyCtxt<'_>, scope_tree: &ScopeTree) -> Span

Returns the span of this Scope. Note that in general the returned span may not correspond to the span of any NodeId in the AST.

Trait Implementations

impl Clone for Scope

fn clone(&self) -> Scope

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Scope

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

Formats the value using the given formatter.

impl<'tcx, __D: TyDecoder<'tcx>> Decodable<__D> for Scope

fn decode(__decoder: &mut __D) -> Result<Self, <__D as Decoder>::Error>

impl<'tcx, __E: TyEncoder<'tcx>> Encodable<__E> for Scope

fn encode(&self, __encoder: &mut __E) -> Result<(), <__E as Encoder>::Error>

impl Hash for Scope

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl<'__ctx> HashStable<StableHashingContext<'__ctx>> for Scope

fn hash_stable(
    &self,
    __hcx: &mut StableHashingContext<'__ctx>,
    __hasher: &mut StableHasher
)

impl<'tcx> Lift<'tcx> for Scope

type Lifted = Self

fn lift_to_tcx(self, _: TyCtxt<'tcx>) -> Option<Self>

impl Ord for Scope

fn cmp(&self, other: &Scope) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl PartialEq<Scope> for Scope

fn eq(&self, other: &Scope) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Scope) -> bool

This method tests for !=.

impl PartialOrd<Scope> for Scope

fn partial_cmp(&self, other: &Scope) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<'a> ToStableHashKey<StableHashingContext<'a>> for Scope

type KeyType = Scope

fn to_stable_hash_key(&self, _: &StableHashingContext<'a>) -> Scope

impl<'tcx> TypeFoldable<'tcx> for Scope

fn super_fold_with<F: TypeFolder<'tcx>>(self, _: &mut F) -> Scope

fn super_visit_with<F: TypeVisitor<'tcx>>(
    &self,
    _: &mut F
) -> ControlFlow<F::BreakTy>

fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self

fn visit_with<V: TypeVisitor<'tcx>>(
    &self,
    visitor: &mut V
) -> ControlFlow<V::BreakTy>

fn has_vars_bound_at_or_above(&self, binder: DebruijnIndex) -> bool

Returns true if self has any late-bound regions that are either bound by binder or bound by some binder outside of binder. If binder is ty::INNERMOST, this indicates whether there are any late-bound regions that appear free.

fn has_vars_bound_above(&self, binder: DebruijnIndex) -> bool

Returns true if this self has any regions that escape binder (and hence are not bound by it).

fn has_escaping_bound_vars(&self) -> bool

fn definitely_has_type_flags(&self, tcx: TyCtxt<'tcx>, flags: TypeFlags) -> bool

fn has_type_flags(&self, flags: TypeFlags) -> bool

fn has_projections(&self) -> bool

fn has_opaque_types(&self) -> bool

fn references_error(&self) -> bool

fn potentially_has_param_types_or_consts(&self) -> bool

fn definitely_has_param_types_or_consts(&self, tcx: TyCtxt<'tcx>) -> bool

fn has_infer_regions(&self) -> bool

fn has_infer_types(&self) -> bool

fn has_infer_types_or_consts(&self) -> bool

fn needs_infer(&self) -> bool

fn has_placeholders(&self) -> bool

fn potentially_needs_subst(&self) -> bool

fn definitely_needs_subst(&self, tcx: TyCtxt<'tcx>) -> bool

fn has_free_regions(&self, tcx: TyCtxt<'tcx>) -> bool

“Free” regions in this context means that it has any region that is not (a) erased or (b) late-bound.

fn has_erased_regions(&self) -> bool

fn has_erasable_regions(&self, tcx: TyCtxt<'tcx>) -> bool

True if there are any un-erased free regions.

fn is_known_global(&self) -> bool

Indicates whether this value definitely references only ‘global’ generic parameters that are the same regardless of what fn we are in. This is used for caching.

fn is_global(&self, tcx: TyCtxt<'tcx>) -> bool

Indicates whether this value references only ‘global’ generic parameters that are the same regardless of what fn we are in. This is used for caching.

fn has_late_bound_regions(&self) -> bool

True if there are any late-bound regions

fn still_further_specializable(&self) -> bool

Indicates whether this value still has parameters/placeholders/inference variables which could be replaced later, in a way that would change the results of impl specialization.

impl Copy for Scope

impl Eq for Scope

impl StructuralEq for Scope

impl StructuralPartialEq for Scope

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference’s “Type Layout” chapter for details on type layout guarantees.

Size: 8 bytes