Struct OutlivesEnvironment

pub struct OutlivesEnvironment<'tcx> {
    pub param_env: ParamEnv<'tcx>,
    free_region_map: FreeRegionMap<'tcx>,
    region_bound_pairs: RegionBoundPairs<'tcx>,
    known_type_outlives: Vec<PolyTypeOutlivesPredicate<'tcx>>,
}

The OutlivesEnvironment collects information about what outlives what in a given type-checking setting. For example, if we have a where-clause like where T: 'a in scope, then the OutlivesEnvironment would record that (in its region_bound_pairs field). Similarly, it contains methods for processing and adding implied bounds into the outlives environment.

Other code at present does not typically take a &OutlivesEnvironment, but rather takes some of its fields (e.g., process_registered_region_obligations wants the region-bound-pairs). There is no mistaking it: the current setup of tracking region information is quite scattered! The OutlivesEnvironment, for example, needs to sometimes be combined with the middle::RegionRelations, to yield a full picture of how (lexical) lifetimes interact. However, I’m reluctant to do more refactoring here, since the setup with NLL is quite different. For example, NLL has no need of RegionRelations, and is solely interested in the OutlivesEnvironment. -nmatsakis

Fields

param_env: ParamEnv<'tcx>

free_region_map: FreeRegionMap<'tcx>

region_bound_pairs: RegionBoundPairs<'tcx>

FIXME: Your first reaction may be that this is a bit strange. RegionBoundPairs does not contain lifetimes, which are instead in the FreeRegionMap, and other known type outlives are stored in the known_type_outlives set. So why do we have these at all? It turns out that removing these and using known_type_outlives everywhere is just enough of a perf regression to matter. This can/should be optimized in the future, though.

known_type_outlives: Vec<PolyTypeOutlivesPredicate<'tcx>>

Implementations

impl<'tcx> OutlivesEnvironment<'tcx>

pub fn from_normalized_bounds( param_env: ParamEnv<'tcx>, known_type_outlives: Vec<PolyTypeOutlivesPredicate<'tcx>>, extra_bounds: impl IntoIterator<Item = OutlivesBound<'tcx>>, ) -> Self

Create a new OutlivesEnvironment from normalized outlives bounds.

pub fn free_region_map(&self) -> &FreeRegionMap<'tcx>

pub fn region_bound_pairs(&self) -> &RegionBoundPairs<'tcx>

pub fn known_type_outlives(&self) -> &[PolyTypeOutlivesPredicate<'tcx>]

Trait Implementations

impl<'tcx> Clone for OutlivesEnvironment<'tcx>

fn clone(&self) -> OutlivesEnvironment<'tcx>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

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: 216 bytes