Trait rustc_hir_analysis::astconv::AstConv

pub trait AstConv<'tcx> {
    // Required methods
    fn tcx(&self) -> TyCtxt<'tcx>;
    fn item_def_id(&self) -> DefId;
    fn get_type_parameter_bounds(
        &self,
        span: Span,
        def_id: LocalDefId,
        assoc_name: Ident
    ) -> GenericPredicates<'tcx>;
    fn re_infer(
        &self,
        param: Option<&GenericParamDef>,
        span: Span
    ) -> Option<Region<'tcx>>;
    fn ty_infer(&self, param: Option<&GenericParamDef>, span: Span) -> Ty<'tcx>;
    fn allow_ty_infer(&self) -> bool;
    fn ct_infer(
        &self,
        ty: Ty<'tcx>,
        param: Option<&GenericParamDef>,
        span: Span
    ) -> Const<'tcx>;
    fn projected_ty_from_poly_trait_ref(
        &self,
        span: Span,
        item_def_id: DefId,
        item_segment: &PathSegment<'tcx>,
        poly_trait_ref: PolyTraitRef<'tcx>
    ) -> Ty<'tcx>;
    fn probe_adt(&self, span: Span, ty: Ty<'tcx>) -> Option<AdtDef<'tcx>>;
    fn set_tainted_by_errors(&self, e: ErrorGuaranteed);
    fn record_ty(&self, hir_id: HirId, ty: Ty<'tcx>, span: Span);
    fn infcx(&self) -> Option<&InferCtxt<'tcx>>;

    // Provided method
    fn astconv(&self) -> &dyn AstConv<'tcx>
       where Self: Sized { ... }
}

Required Methods

fn tcx(&self) -> TyCtxt<'tcx>

fn item_def_id(&self) -> DefId

fn get_type_parameter_bounds( &self, span: Span, def_id: LocalDefId, assoc_name: Ident ) -> GenericPredicates<'tcx>

Returns predicates in scope of the form X: Foo<T>, where X is a type parameter X with the given id def_id and T matches assoc_name. This is a subset of the full set of predicates.

This is used for one specific purpose: resolving “short-hand” associated type references like T::Item. In principle, we would do that by first getting the full set of predicates in scope and then filtering down to find those that apply to T, but this can lead to cycle errors. The problem is that we have to do this resolution in order to create the predicates in the first place. Hence, we have this “special pass”.

fn re_infer( &self, param: Option<&GenericParamDef>, span: Span ) -> Option<Region<'tcx>>

Returns the lifetime to use when a lifetime is omitted (and not elided).

fn ty_infer(&self, param: Option<&GenericParamDef>, span: Span) -> Ty<'tcx>

Returns the type to use when a type is omitted.

fn allow_ty_infer(&self) -> bool

Returns true if _ is allowed in type signatures in the current context.

fn ct_infer( &self, ty: Ty<'tcx>, param: Option<&GenericParamDef>, span: Span ) -> Const<'tcx>

Returns the const to use when a const is omitted.

fn projected_ty_from_poly_trait_ref( &self, span: Span, item_def_id: DefId, item_segment: &PathSegment<'tcx>, poly_trait_ref: PolyTraitRef<'tcx> ) -> Ty<'tcx>

Projecting an associated type from a (potentially) higher-ranked trait reference is more complicated, because of the possibility of late-bound regions appearing in the associated type binding. This is not legal in function signatures for that reason. In a function body, we can always handle it because we can use inference variables to remove the late-bound regions.

fn probe_adt(&self, span: Span, ty: Ty<'tcx>) -> Option<AdtDef<'tcx>>

Returns AdtDef if ty is an ADT. Note that ty might be a projection type that needs normalization. This used to get the enum variants in scope of the type. For example, Self::A could refer to an associated type or to an enum variant depending on the result of this function.

fn set_tainted_by_errors(&self, e: ErrorGuaranteed)

Invoked when we encounter an error from some prior pass (e.g., resolve) that is translated into a ty-error. This is used to help suppress derived errors typeck might otherwise report.

fn record_ty(&self, hir_id: HirId, ty: Ty<'tcx>, span: Span)

fn infcx(&self) -> Option<&InferCtxt<'tcx>>

Provided Methods

fn astconv(&self) -> &dyn AstConv<'tcx>

where Self: Sized,

Implementations

impl<'tcx> dyn AstConv<'tcx> + '_

pub(crate) fn add_implicitly_sized( &self, bounds: &mut Bounds<'tcx>, self_ty: Ty<'tcx>, ast_bounds: &'tcx [GenericBound<'tcx>], self_ty_where_predicates: Option<(LocalDefId, &'tcx [WherePredicate<'tcx>])>, span: Span )

Sets implicitly_sized to true on Bounds if necessary

pub(crate) fn add_bounds<'hir, I: Iterator<Item = &'hir GenericBound<'tcx>>>( &self, param_ty: Ty<'tcx>, ast_bounds: I, bounds: &mut Bounds<'tcx>, bound_vars: &'tcx List<BoundVariableKind>, only_self_bounds: OnlySelfBounds )

where 'tcx: 'hir,

This helper takes a converted parameter type (param_ty) and an unconverted list of bounds:

fn foo<T: Debug>
       ^  ^^^^^ `ast_bounds` parameter, in HIR form
       |
       `param_ty`, in ty form

It adds these ast_bounds into the bounds structure.

A note on binders: there is an implied binder around param_ty and ast_bounds. See instantiate_poly_trait_ref for more details.

pub(crate) fn compute_bounds( &self, param_ty: Ty<'tcx>, ast_bounds: &[GenericBound<'tcx>], filter: PredicateFilter ) -> Bounds<'tcx>

Translates a list of bounds from the HIR into the Bounds data structure. The self-type for the bounds is given by param_ty.

Example:

fn foo<T: Bar + Baz>() { }
//     ^  ^^^^^^^^^ ast_bounds
//     param_ty

The sized_by_default parameter indicates if, in this context, the param_ty should be considered Sized unless there is an explicit ?Sized bound. This would be true in the example above, but is not true in supertrait listings like trait Foo: Bar + Baz.

span should be the declaration size of the parameter.

pub(super) fn add_predicates_for_ast_type_binding( &self, hir_ref_id: HirId, trait_ref: PolyTraitRef<'tcx>, binding: &TypeBinding<'tcx>, bounds: &mut Bounds<'tcx>, speculative: bool, dup_bindings: &mut FxIndexMap<DefId, Span>, path_span: Span, only_self_bounds: OnlySelfBounds ) -> Result<(), ErrorGuaranteed>

Given an HIR binding like Item = Foo or Item: Foo, pushes the corresponding predicates onto bounds.

A note on binders: given something like T: for<'a> Iterator<Item = &'a u32>, the trait_ref here will be for<'a> T: Iterator. The binding data however is from inside the binder (e.g., &'a u32) and hence may reference bound regions.

impl<'tcx> dyn AstConv<'tcx> + '_

pub(crate) fn complain_about_missing_type_params( &self, missing_type_params: Vec<Symbol>, def_id: DefId, span: Span, empty_generic_args: bool )

On missing type parameters, emit an E0393 error and provide a structured suggestion using the type parameter’s name as a placeholder.

pub(crate) fn complain_about_internal_fn_trait( &self, span: Span, trait_def_id: DefId, trait_segment: &PathSegment<'_>, is_impl: bool )

When the code is using the Fn traits directly, instead of the Fn(A) -> B syntax, emit an error and attempt to build a reasonable structured suggestion.

pub(super) fn complain_about_assoc_item_not_found<I>( &self, all_candidates: impl Fn() -> I, ty_param_name: &str, ty_param_def_id: Option<LocalDefId>, assoc_kind: AssocKind, assoc_name: Ident, span: Span, binding: Option<&TypeBinding<'tcx>> ) -> ErrorGuaranteed

where I: Iterator<Item = PolyTraitRef<'tcx>>,

fn complain_about_assoc_kind_mismatch( &self, assoc_item: &AssocItem, assoc_kind: AssocKind, ident: Ident, span: Span, binding: Option<&TypeBinding<'tcx>> ) -> ErrorGuaranteed

pub(super) fn report_ambiguous_associated_type( &self, span: Span, types: &[String], traits: &[String], name: Symbol ) -> ErrorGuaranteed

pub(crate) fn complain_about_ambiguous_inherent_assoc_type( &self, name: Ident, candidates: Vec<DefId>, span: Span ) -> ErrorGuaranteed

fn note_ambiguous_inherent_assoc_type( &self, err: &mut Diag<'_>, candidates: Vec<DefId>, span: Span )

pub(crate) fn complain_about_inherent_assoc_type_not_found( &self, name: Ident, self_ty: Ty<'tcx>, candidates: Vec<(DefId, (DefId, DefId))>, fulfillment_errors: Vec<FulfillmentError<'tcx>>, span: Span ) -> ErrorGuaranteed

pub(crate) fn complain_about_missing_associated_types( &self, associated_types: FxIndexMap<Span, FxIndexSet<DefId>>, potential_assoc_types: Vec<Span>, trait_bounds: &[PolyTraitRef<'_>] )

When there are any missing associated types, emit an E0191 error and attempt to supply a reasonable suggestion on how to write it. For the case of multiple associated types in the same trait bound have the same name (as they come from different supertraits), we instead emit a generic note suggesting using a where clause to constraint instead.

pub(crate) fn maybe_report_similar_assoc_fn( &self, span: Span, qself_ty: Ty<'tcx>, qself: &Ty<'_> ) -> Result<(), ErrorGuaranteed>

On ambiguous associated type, look for an associated function whose name matches the extended path and, if found, emit an E0223 error with a structured suggestion. e.g. for String::from::utf8, suggest String::from_utf8 (#109195)

impl<'tcx> dyn AstConv<'tcx> + '_

pub(super) fn maybe_lint_blanket_trait_impl<G: EmissionGuarantee>( &self, self_ty: &Ty<'_>, diag: &mut Diag<'_, G> )

Make sure that we are in the condition to suggest the blanket implementation.

fn add_generic_param_suggestion( &self, generics: &Generics<'_>, self_ty_span: Span, impl_trait_name: &str ) -> Vec<(Span, String)>

fn maybe_lint_impl_trait(&self, self_ty: &Ty<'_>, diag: &mut Diag<'_>) -> bool

Make sure that we are in the condition to suggest impl Trait.

pub(super) fn maybe_lint_bare_trait(&self, self_ty: &Ty<'_>, in_path: bool)

impl<'tcx> dyn AstConv<'tcx> + '_

pub(super) fn conv_object_ty_poly_trait_ref( &self, span: Span, hir_id: HirId, hir_trait_bounds: &[PolyTraitRef<'tcx>], lifetime: &Lifetime, borrowed: bool, representation: DynKind ) -> Ty<'tcx>

impl<'tcx> dyn AstConv<'tcx> + '_

pub fn ast_region_to_region( &self, lifetime: &Lifetime, def: Option<&GenericParamDef> ) -> Region<'tcx>

pub fn ast_path_args_for_ty( &self, span: Span, def_id: DefId, item_segment: &PathSegment<'tcx> ) -> GenericArgsRef<'tcx>

Given a path path that refers to an item I with the declared generics decl_generics, returns an appropriate set of generic arguments for this particular reference to I.

fn create_args_for_ast_path( &self, span: Span, def_id: DefId, parent_args: &[GenericArg<'tcx>], segment: &PathSegment<'tcx>, self_ty: Option<Ty<'tcx>>, constness: BoundConstness ) -> (GenericArgsRef<'tcx>, GenericArgCountResult)

Given the type/lifetime/const arguments provided to some path (along with an implicit Self, if this is a trait reference), returns the complete set of generic arguments. This may involve applying defaulted type parameters.

Constraints on associated types are not converted here but separately in add_predicates_for_ast_type_binding.

Example:

   T: std::ops::Index<usize, Output = u32>
// ^1 ^^^^^^^^^^^^^^2 ^^^^3  ^^^^^^^^^^^4

1. The self_ty here would refer to the type T.
2. The path in question is the path to the trait std::ops::Index, which will have been resolved to a def_id
3. The generic_args contains info on the <...> contents. The usize type parameters are returned in the GenericArgsRef
4. Associated type bindings like Output = u32 are contained in generic_args.bindings.

Note that the type listing given here is exactly what the user provided.

For (generic) associated types

<Vec<u8> as Iterable<u8>>::Iter::<'a>

We have the parent args are the args for the parent trait: [Vec<u8>, u8] and generic_args are the arguments for the associated type itself: ['a]. The returned GenericArgsRef concatenates these two lists: [Vec<u8>, u8, 'a].

pub fn create_args_for_associated_item( &self, span: Span, item_def_id: DefId, item_segment: &PathSegment<'tcx>, parent_args: GenericArgsRef<'tcx> ) -> GenericArgsRef<'tcx>

pub fn instantiate_mono_trait_ref( &self, trait_ref: &TraitRef<'tcx>, self_ty: Ty<'tcx> ) -> TraitRef<'tcx>

Instantiates the path for the given trait reference, assuming that it’s bound to a valid trait type. Returns the DefId of the defining trait. The type cannot be a type other than a trait type.

If the projections argument is None, then assoc type bindings like Foo<T = X> are disallowed. Otherwise, they are pushed onto the vector given.

pub(crate) fn instantiate_poly_trait_ref( &self, trait_ref: &TraitRef<'tcx>, span: Span, constness: BoundConstness, polarity: ImplPolarity, self_ty: Ty<'tcx>, bounds: &mut Bounds<'tcx>, speculative: bool, only_self_bounds: OnlySelfBounds ) -> GenericArgCountResult

Given a trait bound like Debug, applies that trait bound the given self-type to construct a full trait reference. The resulting trait reference is returned. This may also generate auxiliary bounds, which are added to bounds.

Example:

poly_trait_ref = Iterator<Item = u32>
self_ty = Foo

this would return Foo: Iterator and add <Foo as Iterator>::Item = u32 into bounds.

A note on binders: against our usual convention, there is an implied binder around the self_ty and poly_trait_ref parameters here. So they may reference bound regions. If for example you had for<'a> Foo<'a>: Bar<'a>, then the self_ty would be Foo<'a> where 'a is a bound region at depth 0. Similarly, the poly_trait_ref would be Bar<'a>. The returned poly-trait-ref will have this binder instantiated explicitly, however.

fn ast_path_to_mono_trait_ref( &self, span: Span, trait_def_id: DefId, self_ty: Ty<'tcx>, trait_segment: &PathSegment<'tcx>, is_impl: bool, constness: BoundConstness ) -> TraitRef<'tcx>

fn trait_defines_associated_item_named( &self, trait_def_id: DefId, assoc_kind: AssocKind, assoc_name: Ident ) -> bool

fn ast_path_to_ty( &self, span: Span, did: DefId, item_segment: &PathSegment<'tcx> ) -> Ty<'tcx>

fn find_bound_for_assoc_item( &self, ty_param_def_id: LocalDefId, assoc_name: Ident, span: Span ) -> Result<PolyTraitRef<'tcx>, ErrorGuaranteed>

fn one_bound_for_assoc_item<I>( &self, all_candidates: impl Fn() -> I, ty_param_name: impl Display, ty_param_def_id: Option<LocalDefId>, assoc_kind: AssocKind, assoc_name: Ident, span: Span, binding: Option<&TypeBinding<'tcx>> ) -> Result<PolyTraitRef<'tcx>, ErrorGuaranteed>

where I: Iterator<Item = PolyTraitRef<'tcx>>,

pub fn associated_path_to_ty( &self, hir_ref_id: HirId, span: Span, qself_ty: Ty<'tcx>, qself: &Ty<'_>, assoc_segment: &PathSegment<'tcx>, permit_variants: bool ) -> Result<(Ty<'tcx>, DefKind, DefId), ErrorGuaranteed>

fn lookup_inherent_assoc_ty( &self, name: Ident, segment: &PathSegment<'tcx>, adt_did: DefId, self_ty: Ty<'tcx>, block: HirId, span: Span ) -> Result<Option<(Ty<'tcx>, DefId)>, ErrorGuaranteed>

fn select_inherent_assoc_type_candidates( &self, infcx: &InferCtxt<'tcx>, name: Ident, span: Span, self_ty: Ty<'tcx>, param_env: ParamEnv<'tcx>, candidates: Vec<(DefId, (DefId, DefId))> ) -> Result<(DefId, (DefId, DefId)), ErrorGuaranteed>

fn lookup_assoc_ty( &self, name: Ident, block: HirId, span: Span, scope: DefId ) -> Option<DefId>

fn lookup_assoc_ty_unchecked( &self, name: Ident, block: HirId, scope: DefId ) -> Option<(DefId, DefId)>

fn check_assoc_ty( &self, item: DefId, name: Ident, def_scope: DefId, block: HirId, span: Span )

fn probe_traits_that_match_assoc_ty( &self, qself_ty: Ty<'tcx>, assoc_ident: Ident ) -> Vec<String>

fn qpath_to_ty( &self, span: Span, opt_self_ty: Option<Ty<'tcx>>, item_def_id: DefId, trait_segment: &PathSegment<'tcx>, item_segment: &PathSegment<'tcx>, constness: BoundConstness ) -> Ty<'tcx>

pub fn prohibit_generics<'a>( &self, segments: impl Iterator<Item = &'a PathSegment<'a>> + Clone, extend: impl Fn(&mut Diag<'_>) ) -> bool

pub fn def_ids_for_value_path_segments( &self, segments: &[PathSegment<'_>], self_ty: Option<Ty<'tcx>>, kind: DefKind, def_id: DefId, span: Span ) -> Vec<PathSeg>

pub fn res_to_ty( &self, opt_self_ty: Option<Ty<'tcx>>, path: &Path<'tcx>, hir_id: HirId, permit_variants: bool ) -> Ty<'tcx>

Check a type Path and convert it to a Ty.

pub(crate) fn hir_id_to_bound_ty(&self, hir_id: HirId) -> Ty<'tcx>

pub(crate) fn hir_id_to_bound_const( &self, hir_id: HirId, param_ty: Ty<'tcx> ) -> Const<'tcx>

pub fn ast_ty_to_ty(&self, ast_ty: &Ty<'tcx>) -> Ty<'tcx>

Parses the programmer’s textual representation of a type into our internal notion of a type.

pub fn ast_ty_to_ty_in_path(&self, ast_ty: &Ty<'tcx>) -> Ty<'tcx>

Parses the programmer’s textual representation of a type into our internal notion of a type. This is meant to be used within a path.

fn check_delegation_constraints( &self, sig_id: DefId, span: Span, emit: bool ) -> bool

fn ty_from_delegation( &self, sig_id: DefId, idx: InferDelegationKind, span: Span ) -> Ty<'tcx>

fn ast_ty_to_ty_inner( &self, ast_ty: &Ty<'tcx>, borrowed: bool, in_path: bool ) -> Ty<'tcx>

Turns a hir::Ty into a Ty. For diagnostics’ purposes we keep track of whether trait objects are borrowed like &dyn Trait to avoid emitting redundant errors.

fn impl_trait_ty_to_ty( &self, def_id: DefId, lifetimes: &[GenericArg<'_>], in_trait: bool ) -> Ty<'tcx>

pub fn ty_of_arg( &self, ty: &Ty<'tcx>, expected_ty: Option<Ty<'tcx>> ) -> Ty<'tcx>

pub fn ty_of_fn( &self, hir_id: HirId, unsafety: Unsafety, abi: Abi, decl: &FnDecl<'tcx>, generics: Option<&Generics<'_>>, hir_ty: Option<&Ty<'_>> ) -> PolyFnSig<'tcx>

fn suggest_trait_fn_ty_for_impl_fn_infer( &self, fn_hir_id: HirId, arg_idx: Option<usize> ) -> Option<Ty<'tcx>>

Given a fn_hir_id for a impl function, suggest the type that is found on the corresponding function in the trait that the impl implements, if it exists. If arg_idx is Some, then it corresponds to an input type index, otherwise it corresponds to the return type.

fn validate_late_bound_regions( &self, constrained_regions: FxHashSet<BoundRegionKind>, referenced_regions: FxHashSet<BoundRegionKind>, generate_err: impl Fn(&str) -> Diag<'tcx> )

fn compute_object_lifetime_bound( &self, span: Span, existential_predicates: &'tcx List<PolyExistentialPredicate<'tcx>> ) -> Option<Region<'tcx>>

Given the bounds on an object, determines what single region bound (if any) we can use to summarize this type. The basic idea is that we will use the bound the user provided, if they provided one, and otherwise search the supertypes of trait bounds for region bounds. It may be that we can derive no bound at all, in which case we return None.

Implementors

impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx>