Trait rustc_middle::ty::fold::FallibleTypeFolder

pub trait FallibleTypeFolder<I>: Sized
where
    I: Interner,
{
    type Error;

    // Required method
    fn cx(&self) -> I;

    // Provided methods
    fn try_fold_binder<T>(
        &mut self,
        t: Binder<I, T>,
    ) -> Result<Binder<I, T>, Self::Error>
       where T: TypeFoldable<I> { ... }
    fn try_fold_ty(
        &mut self,
        t: <I as Interner>::Ty,
    ) -> Result<<I as Interner>::Ty, Self::Error> { ... }
    fn try_fold_region(
        &mut self,
        r: <I as Interner>::Region,
    ) -> Result<<I as Interner>::Region, Self::Error> { ... }
    fn try_fold_const(
        &mut self,
        c: <I as Interner>::Const,
    ) -> Result<<I as Interner>::Const, Self::Error> { ... }
    fn try_fold_predicate(
        &mut self,
        p: <I as Interner>::Predicate,
    ) -> Result<<I as Interner>::Predicate, Self::Error> { ... }
}

This trait is implemented for every folding traversal. There is a fold method defined for every type of interest. Each such method has a default that does an “identity” fold.

A blanket implementation of this trait (that defers to the relevant method of TypeFolder) is provided for all infallible folders in order to ensure the two APIs are coherent.

Required Associated Types

type Error

Required Methods

fn cx(&self) -> I

Provided Methods

fn try_fold_binder<T>( &mut self, t: Binder<I, T>, ) -> Result<Binder<I, T>, Self::Error>

where T: TypeFoldable<I>,

fn try_fold_ty( &mut self, t: <I as Interner>::Ty, ) -> Result<<I as Interner>::Ty, Self::Error>

fn try_fold_region( &mut self, r: <I as Interner>::Region, ) -> Result<<I as Interner>::Region, Self::Error>

fn try_fold_const( &mut self, c: <I as Interner>::Const, ) -> Result<<I as Interner>::Const, Self::Error>

fn try_fold_predicate( &mut self, p: <I as Interner>::Predicate, ) -> Result<<I as Interner>::Predicate, Self::Error>

Object Safety

This trait is not object safe.

Implementors

impl<'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for MakeSuggestableFolder<'tcx>

type Error = ()

impl<'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for TryNormalizeAfterErasingRegionsFolder<'tcx>

type Error = NormalizationError<'tcx>

impl<I, F> FallibleTypeFolder<I> for F

where I: Interner, F: TypeFolder<I>,

type Error = !