Enum rustc_middle::ty::inhabitedness::DefIdForest

pub enum DefIdForest {
    Empty,
    Single(DefId),
    Multiple(Arc<[DefId]>),
}

Represents a forest of DefIds closed under the ancestor relation. That is, if a DefId representing a module is contained in the forest then all DefIds defined in that module or submodules are also implicitly contained in the forest.

This is used to represent a set of modules in which a type is visibly uninhabited.

We store the minimal set of DefIds required to represent the whole set. If A and B are DefIds in the DefIdForest, and A is a parent of B, then only A will be stored. When this is used with type_uninhabited_from, there will very rarely be more than one DefId stored.

Variants

Empty

Single(DefId)

Multiple(Arc<[DefId]>)

This variant is very rare. Invariant: >1 elements We use Arc because this is used in the output of a query.

Implementations

impl<'tcx> DefIdForest

pub fn empty() -> DefIdForest

Creates an empty forest.

pub fn full(tcx: TyCtxt<'tcx>) -> DefIdForest

Creates a forest consisting of a single tree representing the entire crate.

pub fn from_id(id: DefId) -> DefIdForest

Creates a forest containing a DefId and all its descendants.

fn as_slice(&self) -> &[DefId]

fn from_slice(root_ids: &[DefId]) -> DefIdForest

pub fn is_empty(&self) -> bool

Tests whether the forest is empty.

fn iter(&self) -> impl Iterator<Item = DefId> + '_

Iterate over the set of roots.

pub fn contains(&self, tcx: TyCtxt<'tcx>, id: DefId) -> bool

Tests whether the forest contains a given DefId.

pub fn intersection<I>(tcx: TyCtxt<'tcx>, iter: I) -> DefIdForest where
    I: IntoIterator<Item = DefIdForest>, 

Calculate the intersection of a collection of forests.

pub fn union<I>(tcx: TyCtxt<'tcx>, iter: I) -> DefIdForest where
    I: IntoIterator<Item = DefIdForest>, 

Calculate the union of a collection of forests.

Trait Implementations

impl Clone for DefIdForest

fn clone(&self) -> DefIdForest

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for DefIdForest

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

Formats the value using the given formatter.

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

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