Trait DefIdVisitor

source

pub trait DefIdVisitor<'tcx> {
    type Result: VisitorResult = ();

    const SHALLOW: bool = false;
    const SKIP_ASSOC_TYS: bool = false;

    // Required methods
    fn tcx(&self) -> TyCtxt<'tcx>;
    fn visit_def_id(
        &mut self,
        def_id: DefId,
        kind: &str,
        descr: &dyn Display,
    ) -> Self::Result;

    // Provided methods
    fn skeleton(&mut self) -> DefIdVisitorSkeleton<'_, 'tcx, Self> { ... }
    fn visit(
        &mut self,
        ty_fragment: impl TypeVisitable<TyCtxt<'tcx>>,
    ) -> Self::Result { ... }
    fn visit_trait(&mut self, trait_ref: TraitRef<'tcx>) -> Self::Result { ... }
    fn visit_predicates(
        &mut self,
        predicates: GenericPredicates<'tcx>,
    ) -> Self::Result { ... }
    fn visit_clauses(
        &mut self,
        clauses: &[(Clause<'tcx>, Span)],
    ) -> Self::Result { ... }
}

Expand description

Implemented to visit all DefIds in a type. Visiting DefIds is useful because visibilities and reachabilities are attached to them. The idea is to visit “all components of a type”, as documented in https://github.com/rust-lang/rfcs/blob/master/text/2145-type-privacy.md#how-to-determine-visibility-of-a-type. The default type visitor (TypeVisitor) does most of the job, but it has some shortcomings. First, it doesn’t have overridable fn visit_trait_ref, so we have to catch trait DefIds manually. Second, it doesn’t visit some type components like signatures of fn types, or traits in impl Trait, see individual comments in DefIdVisitorSkeleton::visit_ty.