# Struct rustc_trait_selection::traits::specialize::specialization_graph::Graph

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    pub struct Graph {
        pub parent: UnordMap<DefId, DefId>,
        pub children: UnordMap<DefId, Children>,
        pub has_errored: Option<ErrorGuaranteed>,
    }

Expand description

A per-trait graph of impls in specialization order. At the moment, this graph forms a tree rooted with the trait itself, with all other nodes representing impls, and parent-child relationships representing specializations.

The graph provides two key services:

- Construction. This implicitly checks for overlapping impls (i.e., impls that overlap but where neither specializes the other – an artifact of the simple “chain” rule.

- Parent extraction. In particular, the graph can give you the immediate parents of a given specializing impl, which is needed for extracting default items amongst other things. In the simple “chain” rule, every impl has at most one parent.

## Fields§

§`parent: UnordMap<DefId, DefId>`

All impls have a parent; the “root” impls have as their parent the `def_id` of the trait.

§`children: UnordMap<DefId, Children>`

The “root” impls are found by looking up the trait’s def_id.

§`has_errored: Option<ErrorGuaranteed>`

Whether an error was emitted while constructing the graph.

## Trait Implementations§

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### impl<'tcx> GraphExt<'tcx> for Graph

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#### fn insert( &mut self, tcx: TyCtxt<'tcx>, impl_def_id: DefId, overlap_mode: OverlapMode ) -> Result<Option<FutureCompatOverlapError<'tcx>>, OverlapError<'tcx>>

Insert a local impl into the specialization graph. If an existing impl conflicts with it (has overlap, but neither specializes the other), information about the area of overlap is returned in the `Err`.

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#### fn record_impl_from_cstore( &mut self, tcx: TyCtxt<'tcx>, parent: DefId, child: DefId )

Insert cached metadata mapping from a child impl back to its parent.

## Auto Trait Implementations§

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### impl RefUnwindSafe for Graph

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### impl Send for Graph

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### impl Sync for Graph

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### impl Unpin for Graph

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### impl UnwindSafe for Graph

## Blanket Implementations§

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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.

## 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: 72 bytes