pub enum ImplSource<'tcx, N> {
Show 13 variants UserDefined(ImplSourceUserDefinedData<'tcx, N>), AutoImpl(ImplSourceAutoImplData<N>), Param(Vec<N>, BoundConstness), Object(ImplSourceObjectData<'tcx, N>), Builtin(ImplSourceBuiltinData<N>), TraitUpcasting(ImplSourceTraitUpcastingData<'tcx, N>), Closure(ImplSourceClosureData<'tcx, N>), FnPointer(ImplSourceFnPointerData<'tcx, N>), DiscriminantKind(ImplSourceDiscriminantKindData), Pointee(ImplSourcePointeeData), Generator(ImplSourceGeneratorData<'tcx, N>), TraitAlias(ImplSourceTraitAliasData<'tcx, N>), ConstDestruct(ImplSourceConstDestructData<N>),
}
Expand description

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 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.

AutoImpl(ImplSourceAutoImplData<N>)

ImplSource for auto trait implementations. This carries the information and nested obligations with regards to an auto implementation for a trait Trait. The nested obligations ensure the trait implementation holds for all the constituent types.

Param(Vec<N>, BoundConstness)

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).

Object(ImplSourceObjectData<'tcx, N>)

Virtual calls through an object.

Builtin(ImplSourceBuiltinData<N>)

Successful resolution for a builtin trait.

TraitUpcasting(ImplSourceTraitUpcastingData<'tcx, N>)

ImplSource for trait upcasting coercion

Closure(ImplSourceClosureData<'tcx, N>)

ImplSource automatically generated for a closure. The DefId is the ID of the closure expression. This is an ImplSource::UserDefined in spirit, but the impl is generated by the compiler and does not appear in the source.

FnPointer(ImplSourceFnPointerData<'tcx, N>)

Same as above, but for a function pointer type with the given signature.

DiscriminantKind(ImplSourceDiscriminantKindData)

ImplSource for a builtin DeterminantKind trait implementation.

Pointee(ImplSourcePointeeData)

ImplSource for a builtin Pointee trait implementation.

Generator(ImplSourceGeneratorData<'tcx, N>)

ImplSource automatically generated for a generator.

TraitAlias(ImplSourceTraitAliasData<'tcx, N>)

ImplSource for a trait alias.

ConstDestruct(ImplSourceConstDestructData<N>)

ImplSource for a const Drop implementation.

Implementations

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

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

This method tests for !=.

Traverses the type in question, typically by calling try_fold_with on each field/element. This is true even for types of interest such as Ty. This should only be called within TypeFolder methods, when non-custom traversals are desired for types of interest. Read more

Traverses the type in question, typically by calling visit_with on each field/element. This is true even for types of interest such as Ty. This should only be called within TypeVisitor methods, when non-custom traversals are desired for types of interest. Read more

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

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

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

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

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. Read more

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

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

True if there are any un-erased free regions.

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. Read more

True if there are any late-bound regions

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. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

This method turns the parameters of a DepNodeConstructor into an opaque Fingerprint to be used in DepNode. Not all DepNodeParams support being turned into a Fingerprint (they don’t need to if the corresponding DepNode is anonymous). Read more

This method tries to recover the query key from the given DepNode, something which is needed when forcing DepNodes during red-green evaluation. The query system will only call this method if fingerprint_style() is not FingerprintStyle::Opaque. It is always valid to return None here, in which case incremental compilation will treat the query as having changed instead of forcing it. Read more

Returns the argument unchanged.

Calls U::from(self).

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

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into)

Uses borrowed data to replace owned data, usually by cloning. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion 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

Size for each variant:

  • UserDefined: 47 bytes
  • AutoImpl: 39 bytes
  • Param: 31 bytes
  • Object: 63 bytes
  • Builtin: 31 bytes
  • TraitUpcasting: 71 bytes
  • Closure: 47 bytes
  • FnPointer: 39 bytes
  • DiscriminantKind: 0 bytes
  • Pointee: 0 bytes
  • Generator: 47 bytes
  • TraitAlias: 47 bytes
  • ConstDestruct: 31 bytes