Struct MapAndCompressBoundVars

struct MapAndCompressBoundVars<'tcx> {
    tcx: TyCtxt<'tcx>,
    binder: DebruijnIndex,
    still_bound_vars: Vec<BoundVariableKind>,
    mapping: FxIndexMap<BoundVar, GenericArg<'tcx>>,
}

Given some where clause like for<'b, 'c> <Self as Trait<'a_identity>>::Gat<'b>: Bound<'c>, the mapping will map 'b back to the GAT’s 'b_identity. Then we need to compress the remaining bound var 'c to index 0.

This folder gives us: for<'c> <Self as Trait<'a_identity>>::Gat<'b_identity>: Bound<'c>, which is sufficient for an item bound for Gat, since all of the GAT’s args are identity.

Fields

tcx: TyCtxt<'tcx>

binder: DebruijnIndex

How deep are we? Makes sure we don’t touch the vars of nested binders.

still_bound_vars: Vec<BoundVariableKind>

List of bound vars that remain unsubstituted because they were not mentioned in the GAT’s args.

mapping: FxIndexMap<BoundVar, GenericArg<'tcx>>

Subtle invariant: If the GenericArg is bound, then it should be stored with the debruijn index of INNERMOST so it can be shifted correctly during substitution.

Trait Implementations

impl<'tcx> TypeFolder<TyCtxt<'tcx>> for MapAndCompressBoundVars<'tcx>

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

fn fold_binder<T>(&mut self, t: Binder<'tcx, T>) -> Binder<'tcx, T>

where Binder<'tcx, T>: TypeSuperFoldable<TyCtxt<'tcx>>,

fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx>

fn fold_region(&mut self, re: Region<'tcx>) -> Region<'tcx>

fn fold_const(&mut self, ct: Const<'tcx>) -> Const<'tcx>

fn fold_predicate(&mut self, p: Predicate<'tcx>) -> Predicate<'tcx>

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: 96 bytes