Struct PoloniusContext 

pub(crate) struct PoloniusContext<'tcx> {
    graph: Option<LocalizedConstraintGraph>,
    pub(crate) live_region_variances: IndexVec<RegionVid, Option<ConstraintDirection>>,
    pub(crate) boring_nll_locals: FxHashSet<Local>,
    pub(crate) deferred_locals_for_liveness: DeferredLocals<'tcx>,
    pub(crate) local_use_map: Option<LocalUseMap>,
}

This struct holds the necessary

• liveness data, created during MIR typeck, and which will be used to lazily compute the polonius localized constraints, during NLL region inference as well as MIR dumping,
• data needed by the borrowck error computation and diagnostics.

Fields

graph: Option<LocalizedConstraintGraph>

The graph from which we extract the localized outlives constraints.

live_region_variances: IndexVec<RegionVid, Option<ConstraintDirection>>

The expected edge direction per live region: the kind of directed edge we’ll create as liveness constraints depends on the variance of types with respect to each contained region.

boring_nll_locals: FxHashSet<Local>

The regions that outlive free regions are used to distinguish relevant live locals from boring locals. A boring local is one whose type contains only such regions. Polonius currently has more boring locals than NLLs so we record the latter to use in errors and diagnostics, to focus on the locals we consider relevant and match NLL diagnostics.

deferred_locals_for_liveness: DeferredLocals<'tcx>

local_use_map: Option<LocalUseMap>

Implementations

impl<'tcx> PoloniusContext<'tcx>

pub(crate) fn compute_loan_liveness( &mut self, infcx: &BorrowckInferCtxt<'tcx>, liveness: &mut LivenessValues, outlives_constraints: impl Iterator<Item = OutlivesConstraint<'tcx>>, universal_regions: &UniversalRegions<'tcx>, body: &Body<'tcx>, move_data: &MoveData<'tcx>, location_map: Rc<DenseLocationMap>, borrow_set: &BorrowSet<'tcx>, )

Computes live loans using the set of loans model for -Zpolonius=next.

First, creates a constraint graph combining regions and CFG points, by:

• converting NLL typeck constraints to be localized
• encoding liveness constraints

Then, this graph is traversed, reachability is recorded as loan liveness, to be used by the loan scope and active loans computations.

The constraint data will be used to compute errors and diagnostics.

Trait Implementations

impl<'tcx> Default for PoloniusContext<'tcx>

fn default() -> Self

Returns the “default value” for a type.

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: 264 bytes