Enum ImplSource

pub enum ImplSource<'tcx, N> {
    UserDefined(ImplSourceUserDefinedData<'tcx, N>),
    Param(ThinVec<N>),
    Builtin(BuiltinImplSource, ThinVec<N>),
}

Given the successful resolution of an obligation, the ImplSource indicates where the impl comes from.

For example, the obligation may be satisfied by a specific impl (case A), or it may be relative to some bound that is in scope (case B).

impl<T:Clone> Clone<T> for Option<T> { ... } // Impl_1
impl<T:Clone> Clone<T> for Box<T> { ... }    // Impl_2
impl Clone for i32 { ... }                   // Impl_3

fn foo<T: Clone>(concrete: Option<Box<i32>>, param: T, mixed: Option<T>) {
    // Case A: ImplSource points at a specific impl. Only possible when
    // type is concretely known. If the impl itself has bounded
    // type parameters, ImplSource will carry resolutions for those as well:
    concrete.clone(); // ImplSource(Impl_1, [ImplSource(Impl_2, [ImplSource(Impl_3)])])

    // Case B: ImplSource must be provided by caller. This applies when
    // type is a type parameter.
    param.clone();    // ImplSource::Param

    // Case C: A mix of cases A and B.
    mixed.clone();    // ImplSource(Impl_1, [ImplSource::Param])
}

The type parameter N

See explanation on ImplSourceUserDefinedData.

Variants

UserDefined(ImplSourceUserDefinedData<'tcx, N>)

ImplSource identifying a particular impl.

Param(ThinVec<N>)

Successful resolution to an obligation provided by the caller for some type parameter. The Vec<N> represents the obligations incurred from normalizing the where-clause (if any).

Builtin(BuiltinImplSource, ThinVec<N>)

Successful resolution for a builtin impl.

Implementations

impl<'tcx, N> ImplSource<'tcx, N>

pub fn nested_obligations(self) -> ThinVec<N>

pub fn borrow_nested_obligations(&self) -> &[N]

pub fn borrow_nested_obligations_mut(&mut self) -> &mut [N]

pub fn map<M, F>(self, f: F) -> ImplSource<'tcx, M>

where F: FnMut(N) -> M,

Trait Implementations

impl<'tcx> ArenaAllocatable<'tcx> for ImplSource<'tcx, ()>

fn allocate_on(self, arena: &'tcx Arena<'tcx>) -> &'tcx mut Self

fn allocate_from_iter( arena: &'tcx Arena<'tcx>, iter: impl IntoIterator<Item = Self>, ) -> &'tcx mut [Self]

impl<'tcx, N: Clone> Clone for ImplSource<'tcx, N>

fn clone(&self) -> ImplSource<'tcx, N>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'tcx, N: Debug> Debug for ImplSource<'tcx, N>

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

Formats the value using the given formatter.

impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for &'tcx ImplSource<'tcx, ()>

fn decode(decoder: &mut D) -> Self

impl<'tcx, N, __D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<__D> for ImplSource<'tcx, N>

where ImplSourceUserDefinedData<'tcx, N>: Decodable<__D>, ThinVec<N>: Decodable<__D>,

fn decode(__decoder: &mut __D) -> Self

impl<'tcx, N, __E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<__E> for ImplSource<'tcx, N>

where ImplSourceUserDefinedData<'tcx, N>: Encodable<__E>, ThinVec<N>: Encodable<__E>,

fn encode(&self, __encoder: &mut __E)

impl<'tcx, '__ctx, N> HashStable<StableHashingContext<'__ctx>> for ImplSource<'tcx, N>

where N: HashStable<StableHashingContext<'__ctx>>,

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

impl<'tcx, N: PartialEq> PartialEq for ImplSource<'tcx, N>

fn eq(&self, other: &ImplSource<'tcx, N>) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for ImplSource<'tcx, ()>

fn decode(decoder: &mut D) -> &'tcx Self

impl<'tcx, N> TypeFoldable<TyCtxt<'tcx>> for ImplSource<'tcx, N>

where N: TypeFoldable<TyCtxt<'tcx>>,

fn try_fold_with<__F: FallibleTypeFolder<TyCtxt<'tcx>>>( self, __folder: &mut __F, ) -> Result<Self, __F::Error>

The entry point for folding. To fold a value t with a folder f call: t.try_fold_with(f).

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

where F: TypeFolder<I>,

A convenient alternative to try_fold_with for use with infallible folders. Do not override this method, to ensure coherence with try_fold_with.

impl<'tcx, N> TypeVisitable<TyCtxt<'tcx>> for ImplSource<'tcx, N>

where N: TypeVisitable<TyCtxt<'tcx>>,

fn visit_with<__V: TypeVisitor<TyCtxt<'tcx>>>( &self, __visitor: &mut __V, ) -> __V::Result

The entry point for visiting. To visit a value t with a visitor v call: t.visit_with(v).

impl<'tcx, N: Eq> Eq for ImplSource<'tcx, N>

impl<'tcx, N> StructuralPartialEq for ImplSource<'tcx, N>

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: 32 bytes

Size for each variant:

• UserDefined: 24 bytes
• Param: 8 bytes
• Builtin: 24 bytes