Struct rustc_infer::infer::error_reporting::need_type_info::FindInferSourceVisitor

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>>,
}

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

Fields

infcx: &'a InferCtxt<'tcx>

typeck_results: &'a TypeckResults<'tcx>

target: GenericArg<'tcx>

attempt: usize

infer_source_cost: usize

infer_source: Option<InferSource<'tcx>>

Implementations

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

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

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.

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.

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

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

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

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.

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

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

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

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

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

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

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.

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.

fn visit_local(&mut self, local: &'tcx Local<'tcx>)

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

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

fn visit_nested_item(&mut self, id: ItemId)

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.

fn visit_nested_trait_item(&mut self, id: TraitItemId)

Like visit_nested_item(), but for trait items. See visit_nested_item() for advice on when to override this method.

fn visit_nested_impl_item(&mut self, id: ImplItemId)

Like visit_nested_item(), but for impl items. See visit_nested_item() for advice on when to override this method.

fn visit_nested_foreign_item(&mut self, id: ForeignItemId)

Like visit_nested_item(), but for foreign items. See visit_nested_item() for advice on when to override this method.

fn visit_nested_body(&mut self, id: BodyId)

Invoked to visit the body of a function, method or closure. Like visit_nested_item, does nothing by default unless you override Self::NestedFilter.

fn visit_param(&mut self, param: &'v Param<'v>)

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

Visits the top-level item and (optionally) nested items / impl items. See visit_nested_item for details.

fn visit_id(&mut self, _hir_id: HirId)

fn visit_name(&mut self, _name: Symbol)

fn visit_ident(&mut self, ident: Ident)

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

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

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

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

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

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

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

fn visit_array_length(&mut self, len: &'v ArrayLen)

fn visit_anon_const(&mut self, c: &'v AnonConst)

fn visit_inline_const(&mut self, c: &'v ConstBlock)

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

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

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

fn visit_const_param_default(&mut self, _param: HirId, ct: &'v AnonConst)

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

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

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

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

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

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

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

fn visit_trait_item_ref(&mut self, ii: &'v TraitItemRef)

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

fn visit_foreign_item_ref(&mut self, ii: &'v ForeignItemRef)

fn visit_impl_item_ref(&mut self, ii: &'v ImplItemRef)

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

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

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

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

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

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

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

fn visit_label(&mut self, label: &'v Label)

fn visit_infer(&mut self, inf: &'v InferArg)

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

fn visit_lifetime(&mut self, lifetime: &'v Lifetime)

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

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

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

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

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

fn visit_attribute(&mut self, _attr: &'v Attribute)

fn visit_associated_item_kind(&mut self, kind: &'v AssocItemKind)

fn visit_defaultness(&mut self, defaultness: &'v Defaultness)

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

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