struct FindInferSourceVisitor<'a, 'tcx> {
    infcx: &'a InferCtxt<'tcx>,
    typeck_results: &'a TypeckResults<'tcx>,
    target: GenericArg<'tcx>,
    attempt: usize,
    infer_source_cost: usize,
    infer_source: Option<InferSource<'tcx>>,
}
Expand description

A visitor which searches for the “best” spot to use in the inference error.

For this it walks over the hir body and tries to check all places where inference variables could be bound.

While doing so, the currently best spot is stored in infer_source. For details on how we rank spots, see Self::source_cost

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§infcx: &'a InferCtxt<'tcx>§typeck_results: &'a TypeckResults<'tcx>§target: GenericArg<'tcx>§attempt: usize§infer_source_cost: usize§infer_source: Option<InferSource<'tcx>>

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impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx>

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fn new( infcx: &'a InferCtxt<'tcx>, typeck_results: &'a TypeckResults<'tcx>, target: GenericArg<'tcx> ) -> Self

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fn source_cost(&self, source: &InferSource<'tcx>) -> usize

Computes cost for the given source.

Sources with a small cost are prefer and should result in a clearer and idiomatic suggestion.

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fn update_infer_source(&mut self, new_source: InferSource<'tcx>)

Uses fn source_cost to determine whether this inference source is preferable to previous sources. We generally prefer earlier sources.

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fn node_args_opt(&self, hir_id: HirId) -> Option<GenericArgsRef<'tcx>>

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fn opt_node_type(&self, hir_id: HirId) -> Option<Ty<'tcx>>

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fn generic_arg_is_target(&self, arg: GenericArg<'tcx>) -> bool

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fn generic_arg_contains_target(&self, arg: GenericArg<'tcx>) -> bool

Does this generic argument contain our target inference variable in a way which can be written by the user.

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fn expr_inferred_arg_iter( &self, expr: &'tcx Expr<'tcx> ) -> Box<dyn Iterator<Item = InsertableGenericArgs<'tcx>> + 'a>

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fn resolved_path_inferred_arg_iter( &self, path: &'tcx Path<'tcx>, args: GenericArgsRef<'tcx> ) -> impl Iterator<Item = InsertableGenericArgs<'tcx>> + 'a

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fn path_inferred_arg_iter( &self, hir_id: HirId, args: GenericArgsRef<'tcx>, qpath: &'tcx QPath<'tcx> ) -> Box<dyn Iterator<Item = InsertableGenericArgs<'tcx>> + 'a>

Trait Implementations§

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impl<'a, 'tcx> Visitor<'tcx> for FindInferSourceVisitor<'a, 'tcx>

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fn visit_body(&mut self, body: &'tcx Body<'tcx>)

For closures, we first visit the parameters and then the content, as we prefer those.

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type NestedFilter = OnlyBodies

Override this type to control which nested HIR are visited; see NestedFilter for details. If you override this type, you must also override nested_visit_map. Read more
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fn nested_visit_map(&mut self) -> Self::Map

If type NestedFilter is set to visit nested items, this method must also be overridden to provide a map to retrieve nested items.
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fn visit_local(&mut self, local: &'tcx Local<'tcx>)

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fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>)

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type Map = <Self::NestedFilter as NestedFilter<'v>>::Map

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type Result = ()

The result type of the visit_* methods. Can be either (), or ControlFlow<T>.
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fn visit_nested_item(&mut self, id: ItemId) -> Self::Result

Invoked when a nested item is encountered. By default, when Self::NestedFilter is nested_filter::None, this method does nothing. You probably don’t want to override this method – instead, override Self::NestedFilter or use the “shallow” or “deep” visit patterns described at rustc_hir::intravisit. The only reason to override this method is if you want a nested pattern but cannot supply a Map; see nested_visit_map for advice.
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fn visit_nested_trait_item(&mut self, id: TraitItemId) -> Self::Result

Like visit_nested_item(), but for trait items. See visit_nested_item() for advice on when to override this method.
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fn visit_nested_impl_item(&mut self, id: ImplItemId) -> Self::Result

Like visit_nested_item(), but for impl items. See visit_nested_item() for advice on when to override this method.
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fn visit_nested_foreign_item(&mut self, id: ForeignItemId) -> Self::Result

Like visit_nested_item(), but for foreign items. See visit_nested_item() for advice on when to override this method.
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fn visit_nested_body(&mut self, id: BodyId) -> Self::Result

Invoked to visit the body of a function, method or closure. Like visit_nested_item, does nothing by default unless you override Self::NestedFilter.
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fn visit_param(&mut self, param: &'v Param<'v>) -> Self::Result

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fn visit_item(&mut self, i: &'v Item<'v>) -> Self::Result

Visits the top-level item and (optionally) nested items / impl items. See visit_nested_item for details.
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fn visit_id(&mut self, _hir_id: HirId) -> Self::Result

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fn visit_name(&mut self, _name: Symbol) -> Self::Result

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fn visit_ident(&mut self, ident: Ident) -> Self::Result

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fn visit_mod(&mut self, m: &'v Mod<'v>, _s: Span, n: HirId) -> Self::Result

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fn visit_foreign_item(&mut self, i: &'v ForeignItem<'v>) -> Self::Result

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fn visit_block(&mut self, b: &'v Block<'v>) -> Self::Result

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fn visit_stmt(&mut self, s: &'v Stmt<'v>) -> Self::Result

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fn visit_arm(&mut self, a: &'v Arm<'v>) -> Self::Result

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fn visit_pat(&mut self, p: &'v Pat<'v>) -> Self::Result

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fn visit_pat_field(&mut self, f: &'v PatField<'v>) -> Self::Result

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fn visit_array_length(&mut self, len: &'v ArrayLen) -> Self::Result

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fn visit_anon_const(&mut self, c: &'v AnonConst) -> Self::Result

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fn visit_inline_const(&mut self, c: &'v ConstBlock) -> Self::Result

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fn visit_expr_field(&mut self, field: &'v ExprField<'v>) -> Self::Result

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fn visit_ty(&mut self, t: &'v Ty<'v>) -> Self::Result

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fn visit_generic_param(&mut self, p: &'v GenericParam<'v>) -> Self::Result

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fn visit_const_param_default( &mut self, _param: HirId, ct: &'v AnonConst ) -> Self::Result

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fn visit_generics(&mut self, g: &'v Generics<'v>) -> Self::Result

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fn visit_where_predicate( &mut self, predicate: &'v WherePredicate<'v> ) -> Self::Result

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fn visit_fn_ret_ty(&mut self, ret_ty: &'v FnRetTy<'v>) -> Self::Result

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fn visit_fn_decl(&mut self, fd: &'v FnDecl<'v>) -> Self::Result

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fn visit_fn( &mut self, fk: FnKind<'v>, fd: &'v FnDecl<'v>, b: BodyId, _: Span, id: LocalDefId ) -> Self::Result

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fn visit_use( &mut self, path: &'v Path<'v, SmallVec<[Res; 3]>>, hir_id: HirId ) -> Self::Result

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fn visit_trait_item(&mut self, ti: &'v TraitItem<'v>) -> Self::Result

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fn visit_trait_item_ref(&mut self, ii: &'v TraitItemRef) -> Self::Result

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fn visit_impl_item(&mut self, ii: &'v ImplItem<'v>) -> Self::Result

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fn visit_foreign_item_ref(&mut self, ii: &'v ForeignItemRef) -> Self::Result

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fn visit_impl_item_ref(&mut self, ii: &'v ImplItemRef) -> Self::Result

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fn visit_trait_ref(&mut self, t: &'v TraitRef<'v>) -> Self::Result

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fn visit_param_bound(&mut self, bounds: &'v GenericBound<'v>) -> Self::Result

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fn visit_poly_trait_ref(&mut self, t: &'v PolyTraitRef<'v>) -> Self::Result

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fn visit_variant_data(&mut self, s: &'v VariantData<'v>) -> Self::Result

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fn visit_field_def(&mut self, s: &'v FieldDef<'v>) -> Self::Result

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fn visit_enum_def( &mut self, enum_definition: &'v EnumDef<'v>, item_id: HirId ) -> Self::Result

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fn visit_variant(&mut self, v: &'v Variant<'v>) -> Self::Result

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fn visit_label(&mut self, label: &'v Label) -> Self::Result

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fn visit_infer(&mut self, inf: &'v InferArg) -> Self::Result

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fn visit_generic_arg(&mut self, generic_arg: &'v GenericArg<'v>) -> Self::Result

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fn visit_lifetime(&mut self, lifetime: &'v Lifetime) -> Self::Result

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fn visit_qpath( &mut self, qpath: &'v QPath<'v>, id: HirId, _span: Span ) -> Self::Result

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fn visit_path(&mut self, path: &Path<'v>, _id: HirId) -> Self::Result

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fn visit_path_segment( &mut self, path_segment: &'v PathSegment<'v> ) -> Self::Result

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fn visit_generic_args( &mut self, generic_args: &'v GenericArgs<'v> ) -> Self::Result

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fn visit_assoc_type_binding( &mut self, type_binding: &'v TypeBinding<'v> ) -> Self::Result

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fn visit_attribute(&mut self, _attr: &'v Attribute) -> Self::Result

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fn visit_associated_item_kind( &mut self, kind: &'v AssocItemKind ) -> Self::Result

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fn visit_defaultness(&mut self, defaultness: &'v Defaultness) -> Self::Result

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fn visit_inline_asm( &mut self, asm: &'v InlineAsm<'v>, id: HirId ) -> Self::Result

Auto Trait Implementations§

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impl<'a, 'tcx> !DynSend for FindInferSourceVisitor<'a, 'tcx>

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impl<'a, 'tcx> !DynSync for FindInferSourceVisitor<'a, 'tcx>

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impl<'a, 'tcx> !RefUnwindSafe for FindInferSourceVisitor<'a, 'tcx>

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impl<'a, 'tcx> !Send for FindInferSourceVisitor<'a, 'tcx>

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impl<'a, 'tcx> !Sync for FindInferSourceVisitor<'a, 'tcx>

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impl<'a, 'tcx> Unpin for FindInferSourceVisitor<'a, 'tcx>

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impl<'a, 'tcx> !UnwindSafe for FindInferSourceVisitor<'a, 'tcx>

Blanket Implementations§

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impl<T> Aligned for T

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const ALIGN: Alignment = _

Alignment of Self.
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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, R> CollectAndApply<T, R> for T

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fn collect_and_apply<I, F>(iter: I, f: F) -> R
where I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

Equivalent to f(&iter.collect::<Vec<_>>()).

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type Output = R

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impl<T> Filterable for T

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fn filterable( self, filter_name: &'static str ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

Creates a filterable data provider with the given name for debugging. 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> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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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<P> IntoQueryParam<P> for P

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impl<T> MaybeResult<T> for T

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type Error = !

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fn from(_: Result<T, <T as MaybeResult<T>>::Error>) -> T

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fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>

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impl<T> Pointable for T

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const ALIGN: usize = _

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> Same for T

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type Output = T

Should always be Self
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impl<'tcx, T> ToPredicate<'tcx, T> for T

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fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> T

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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.
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impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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fn vzip(self) -> V

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impl<Tcx, T> Value<Tcx> for T
where Tcx: DepContext,

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default fn from_cycle_error( tcx: Tcx, cycle_error: &CycleError, _guar: ErrorGuaranteed ) -> T

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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
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impl<'a, T> Captures<'a> for T
where T: ?Sized,

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impl<T> ErasedDestructor for T
where T: 'static,

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: 104 bytes