# Trait rustc_trait_selection::infer::canonical::ir::fold::TypeSuperFoldable

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    pub trait TypeSuperFoldable<I>: TypeFoldable<I>where
        I: Interner,{
        // Required method
        fn try_super_fold_with<F>(
            self,
            folder: &mut F,
        ) -> Result<Self, <F as FallibleTypeFolder<I>>::Error>
           where F: FallibleTypeFolder<I>;

        // Provided method
        fn super_fold_with<F>(self, folder: &mut F) -> Self
           where F: TypeFolder<I> { ... }
    }

## Required Methods§

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#### fn try_super_fold_with<F>( self, folder: &mut F, ) -> Result<Self, <F as FallibleTypeFolder<I>>::Error>
where F: FallibleTypeFolder<I>,

Provides a default fold for a recursive type of interest. This should only be called within `TypeFolder` methods, when a non-custom traversal is desired for the value of the type of interest passed to that method. For example, in `MyFolder::try_fold_ty(ty)`, it is valid to call `ty.try_super_fold_with(self)`, but any other folding should be done with `xyz.try_fold_with(self)`.

## Provided Methods§

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#### fn super_fold_with<F>(self, folder: &mut F) -> Self
where F: TypeFolder<I>,

A convenient alternative to `try_super_fold_with` for use with infallible folders. Do not override this method, to ensure coherence with `try_super_fold_with`.

## Object Safety§

This trait is not object safe.

## Implementations on Foreign Types§

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### impl<'tcx> TypeSuperFoldable<TyCtxt<'tcx>> for Const<'tcx>

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#### fn try_super_fold_with<F>( self, folder: &mut F, ) -> Result<Const<'tcx>, <F as FallibleTypeFolder<TyCtxt<'tcx>>>::Error>
where F: FallibleTypeFolder<TyCtxt<'tcx>>,

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### impl<'tcx> TypeSuperFoldable<TyCtxt<'tcx>> for Predicate<'tcx>

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#### fn try_super_fold_with<F>( self, folder: &mut F, ) -> Result<Predicate<'tcx>, <F as FallibleTypeFolder<TyCtxt<'tcx>>>::Error>
where F: FallibleTypeFolder<TyCtxt<'tcx>>,

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### impl<'tcx> TypeSuperFoldable<TyCtxt<'tcx>> for Ty<'tcx>

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#### fn try_super_fold_with<F>( self, folder: &mut F, ) -> Result<Ty<'tcx>, <F as FallibleTypeFolder<TyCtxt<'tcx>>>::Error>
where F: FallibleTypeFolder<TyCtxt<'tcx>>,

## Implementors§

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### impl<I, T> TypeSuperFoldable<I> for Binder<I, T>
where I: Interner, T: TypeFoldable<I>,