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

struct FindInferSourceVisitor<'a, 'tcx> {
    tecx: &'a TypeErrCtxt<'a, '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

tecx: &'a TypeErrCtxt<'a, '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( tecx: &'a TypeErrCtxt<'a, '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 LetStmt<'tcx>)

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

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

type Result = ()

The result type of the visit_* methods. Can be either (), or ControlFlow<T>.

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.

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.

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.

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.

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.

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

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.

fn visit_id(&mut self, _hir_id: HirId) -> Self::Result

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

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

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

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

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

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

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

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

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

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

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

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

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

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

fn visit_pattern_type_pattern(&mut self, _p: &'v Pat<'v>)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

fn visit_precise_capturing_arg( &mut self, arg: &'v PreciseCapturingArg<'v> ) -> Self::Result

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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