Struct rustc::infer::region_constraints::RegionConstraintCollector

pub struct RegionConstraintCollector<'tcx> { /* fields omitted */ }

🔬 This is a nightly-only experimental API. (rustc_private)

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Methods

impl<'tcx> RegionConstraintCollector<'tcx>

pub fn new() -> RegionConstraintCollector<'tcx>

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pub fn var_origins(&self) -> &VarOrigins

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pub fn into_origins_and_data(self) -> (VarOrigins, RegionConstraintData<'tcx>)

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Once all the constraints have been gathered, extract out the final data.

Not legal during a snapshot.

pub fn take_and_reset_data(&mut self) -> RegionConstraintData<'tcx>

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Takes (and clears) the current set of constraints. Note that the set of variables remains intact, but all relationships between them are reset. This is used during NLL checking to grab the set of constraints that arose from a particular operation.

We don't want to leak relationships between variables between points because just because (say) r1 == r2 was true at some point P in the graph doesn't imply that it will be true at some other point Q, in NLL.

Not legal during a snapshot.

pub fn start_snapshot(&mut self) -> RegionSnapshot

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pub fn commit(&mut self, snapshot: RegionSnapshot)

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pub fn rollback_to(&mut self, snapshot: RegionSnapshot)

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pub fn new_region_var(&mut self, origin: RegionVariableOrigin) -> RegionVid

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pub fn var_origin(&self, vid: RegionVid) -> RegionVariableOrigin

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Returns the origin for the given variable.

pub fn push_skolemized(
    &mut self,
    tcx: TyCtxt<'_, '_, 'tcx>,
    br: BoundRegion,
    snapshot: &RegionSnapshot
) -> Region<'tcx>

🔬 This is a nightly-only experimental API. (rustc_private)

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Creates a new skolemized region. Skolemized regions are fresh regions used when performing higher-ranked computations. They must be used in a very particular way and are never supposed to "escape" out into error messages or the code at large.

The idea is to always create a snapshot. Skolemized regions can be created in the context of this snapshot, but before the snapshot is committed or rolled back, they must be popped (using pop_skolemized_regions), so that their numbers can be recycled. Normally you don't have to think about this: you use the APIs in higher_ranked/mod.rs, such as skolemize_late_bound_regions and plug_leaks, which will guide you on this path (ensure that the SkolemizationMap is consumed and you are good). There are also somewhat extensive comments in higher_ranked/README.md.

The snapshot argument to this function is not really used; it's just there to make it explicit which snapshot bounds the skolemized region that results. It should always be the top-most snapshot.

pub fn pop_skolemized(
    &mut self,
    _tcx: TyCtxt<'_, '_, 'tcx>,
    skols: &FxHashSet<Region<'tcx>>,
    snapshot: &RegionSnapshot
)

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Removes all the edges to/from the skolemized regions that are in skols. This is used after a higher-ranked operation completes to remove all trace of the skolemized regions created in that time.

pub fn new_bound(
    &mut self,
    tcx: TyCtxt<'_, '_, 'tcx>,
    debruijn: DebruijnIndex
) -> Region<'tcx>

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pub fn add_given(&mut self, sub: Region<'tcx>, sup: RegionVid)

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pub fn make_eqregion(
    &mut self,
    origin: SubregionOrigin<'tcx>,
    sub: Region<'tcx>,
    sup: Region<'tcx>
)

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pub fn make_subregion(
    &mut self,
    origin: SubregionOrigin<'tcx>,
    sub: Region<'tcx>,
    sup: Region<'tcx>
)

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pub fn verify_generic_bound(
    &mut self,
    origin: SubregionOrigin<'tcx>,
    kind: GenericKind<'tcx>,
    sub: Region<'tcx>,
    bound: VerifyBound<'tcx>
)

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See Verify::VerifyGenericBound

pub fn lub_regions(
    &mut self,
    tcx: TyCtxt<'_, '_, 'tcx>,
    origin: SubregionOrigin<'tcx>,
    a: Region<'tcx>,
    b: Region<'tcx>
) -> Region<'tcx>

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pub fn glb_regions(
    &mut self,
    tcx: TyCtxt<'_, '_, 'tcx>,
    origin: SubregionOrigin<'tcx>,
    a: Region<'tcx>,
    b: Region<'tcx>
) -> Region<'tcx>

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pub fn opportunistic_resolve_var(
    &mut self,
    tcx: TyCtxt<'_, '_, 'tcx>,
    rid: RegionVid
) -> Region<'tcx>

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Important traits for Vec<u8>

impl Write for Vec<u8>

pub fn vars_created_since_snapshot(
    &self,
    mark: &RegionSnapshot
) -> Vec<RegionVid>

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pub fn tainted(
    &self,
    tcx: TyCtxt<'_, '_, 'tcx>,
    mark: &RegionSnapshot,
    r0: Region<'tcx>,
    directions: TaintDirections
) -> FxHashSet<Region<'tcx>>

🔬 This is a nightly-only experimental API. (rustc_private)

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Computes all regions that have been related to r0 since the mark mark was made---r0 itself will be the first entry. The directions parameter controls what kind of relations are considered. For example, one can say that only "incoming" edges to r0 are desired, in which case one will get the set of regions {r|r <= r0}. This is used when checking whether skolemized regions are being improperly related to other regions.