Struct rustc_trait_selection::infer::outlives::verify::VerifyBoundCx

pub struct VerifyBoundCx<'cx, 'tcx> {
    tcx: TyCtxt<'tcx>,
    region_bound_pairs: &'cx Vec<(&'tcx RegionKind, GenericKind<'tcx>)>,
    implicit_region_bound: Option<&'tcx RegionKind>,
    param_env: ParamEnv<'tcx>,
}

The TypeOutlives struct has the job of "lowering" a T: 'a obligation into a series of 'a: 'b constraints and "verifys", as described on the module comment. The final constraints are emitted via a "delegate" of type D -- this is usually the infcx, which accrues them into the region_obligations code, but for NLL we use something else.

Fields

tcx: TyCtxt<'tcx>

region_bound_pairs: &'cx Vec<(&'tcx RegionKind, GenericKind<'tcx>)>

implicit_region_bound: Option<&'tcx RegionKind>

param_env: ParamEnv<'tcx>

Implementations

impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx>

pub fn new(
    tcx: TyCtxt<'tcx>,
    region_bound_pairs: &'cx Vec<(&'tcx RegionKind, GenericKind<'tcx>)>,
    implicit_region_bound: Option<&'tcx RegionKind>,
    param_env: ParamEnv<'tcx>
) -> VerifyBoundCx<'cx, 'tcx>

pub fn generic_bound(&self, generic: GenericKind<'tcx>) -> VerifyBound<'tcx>

Returns a "verify bound" that encodes what we know about generic and the regions it outlives.

pub fn projection_approx_declared_bounds_from_env(
    &self,
    projection_ty: ProjectionTy<'tcx>
) -> Vec<OutlivesPredicate<&'tcx TyS<'tcx>, &'tcx RegionKind>>

Given a projection like T::Item, searches the environment for where-clauses like T::Item: 'a. Returns the set of regions 'a that it finds.

This is an "approximate" check -- it may not find all applicable bounds, and not all the bounds it returns can be relied upon. In particular, this check ignores region identity. So, for example, if we have <T as Trait<'0>>::Item where '0 is a region variable, and the user has <T as Trait<'a>>::Item: 'b in the environment, then the clause from the environment only applies if '0 = 'a, which we don't know yet. But we would still include 'b in this list.

pub fn projection_declared_bounds_from_trait(
    &self,
    projection_ty: ProjectionTy<'tcx>
) -> impl Iterator<Item = &'tcx RegionKind> + Captures<'tcx> + 'cx

Searches the where-clauses in scope for regions that projection_ty is known to outlive. Currently requires an exact match.

pub fn projection_bound(
    &self,
    projection_ty: ProjectionTy<'tcx>
) -> VerifyBound<'tcx>