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use rustc::mir::Mir;
use rustc::infer::region_constraints::Constraint;
use rustc::infer::region_constraints::RegionConstraintData;
use rustc::infer::region_constraints::{Verify, VerifyBound};
use rustc::ty;
use syntax::codemap::Span;
use super::region_infer::{TypeTest, RegionInferenceContext, RegionTest};
use super::type_check::Locations;
use super::type_check::MirTypeckRegionConstraints;
use super::type_check::OutlivesSet;
pub(super) fn generate<'tcx>(
regioncx: &mut RegionInferenceContext<'tcx>,
mir: &Mir<'tcx>,
constraints: &MirTypeckRegionConstraints<'tcx>,
) {
SubtypeConstraintGenerator { regioncx, mir }.generate(constraints);
}
struct SubtypeConstraintGenerator<'cx, 'tcx: 'cx> {
regioncx: &'cx mut RegionInferenceContext<'tcx>,
mir: &'cx Mir<'tcx>,
}
impl<'cx, 'tcx> SubtypeConstraintGenerator<'cx, 'tcx> {
fn generate(&mut self, constraints: &MirTypeckRegionConstraints<'tcx>) {
let MirTypeckRegionConstraints {
liveness_set,
outlives_sets,
} = constraints;
debug!(
"generate(liveness_set={} items, outlives_sets={} items)",
liveness_set.len(),
outlives_sets.len()
);
for (region, location, cause) in liveness_set {
debug!("generate: {:#?} is live at {:#?}", region, location);
let region_vid = self.to_region_vid(region);
self.regioncx.add_live_point(region_vid, *location, &cause);
}
for OutlivesSet { locations, data } in outlives_sets {
debug!("generate: constraints at: {:#?}", locations);
let RegionConstraintData {
constraints,
verifys,
givens,
} = data;
let span = self.mir.source_info(locations.from_location).span;
for constraint in constraints.keys() {
debug!("generate: constraint: {:?}", constraint);
let (a_vid, b_vid) = match constraint {
Constraint::VarSubVar(a_vid, b_vid) => (*a_vid, *b_vid),
Constraint::RegSubVar(a_r, b_vid) => (self.to_region_vid(a_r), *b_vid),
Constraint::VarSubReg(a_vid, b_r) => (*a_vid, self.to_region_vid(b_r)),
Constraint::RegSubReg(a_r, b_r) => {
(self.to_region_vid(a_r), self.to_region_vid(b_r))
}
};
self.regioncx
.add_outlives(span, b_vid, a_vid, locations.at_location);
}
for verify in verifys {
let type_test = self.verify_to_type_test(verify, span, locations);
self.regioncx.add_type_test(type_test);
}
assert!(
givens.is_empty(),
"MIR type-checker does not use givens (thank goodness)"
);
}
}
fn verify_to_type_test(
&self,
verify: &Verify<'tcx>,
span: Span,
locations: &Locations,
) -> TypeTest<'tcx> {
let generic_kind = verify.kind;
let lower_bound = self.to_region_vid(verify.region);
let point = locations.at_location;
let test = self.verify_bound_to_region_test(&verify.bound);
TypeTest {
generic_kind,
lower_bound,
point,
span,
test,
}
}
fn verify_bound_to_region_test(&self, verify_bound: &VerifyBound<'tcx>) -> RegionTest {
match verify_bound {
VerifyBound::AnyRegion(regions) => RegionTest::IsOutlivedByAnyRegionIn(
regions.iter().map(|r| self.to_region_vid(r)).collect(),
),
VerifyBound::AllRegions(regions) => RegionTest::IsOutlivedByAllRegionsIn(
regions.iter().map(|r| self.to_region_vid(r)).collect(),
),
VerifyBound::AnyBound(bounds) => RegionTest::Any(
bounds
.iter()
.map(|b| self.verify_bound_to_region_test(b))
.collect(),
),
VerifyBound::AllBounds(bounds) => RegionTest::All(
bounds
.iter()
.map(|b| self.verify_bound_to_region_test(b))
.collect(),
),
}
}
fn to_region_vid(&self, r: ty::Region<'tcx>) -> ty::RegionVid {
if let ty::ReVar(vid) = r {
*vid
} else {
self.regioncx.to_region_vid(r)
}
}
}