1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use borrow_check::location::LocationTable;
use borrow_check::nll::facts::AllFacts;
use borrow_check::nll::region_infer::{OutlivesConstraint, RegionTest, TypeTest};
use borrow_check::nll::type_check::Locations;
use borrow_check::nll::universal_regions::UniversalRegions;
use rustc::infer::region_constraints::Constraint;
use rustc::infer::region_constraints::RegionConstraintData;
use rustc::infer::region_constraints::{Verify, VerifyBound};
use rustc::mir::{Location, Mir};
use rustc::ty;
use syntax::codemap::Span;

crate struct ConstraintConversion<'a, 'tcx: 'a> {
    mir: &'a Mir<'tcx>,
    universal_regions: &'a UniversalRegions<'tcx>,
    location_table: &'a LocationTable,
    outlives_constraints: &'a mut Vec<OutlivesConstraint>,
    type_tests: &'a mut Vec<TypeTest<'tcx>>,
    all_facts: &'a mut Option<AllFacts>,

}

impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
    crate fn new(
        mir: &'a Mir<'tcx>,
        universal_regions: &'a UniversalRegions<'tcx>,
        location_table: &'a LocationTable,
        outlives_constraints: &'a mut Vec<OutlivesConstraint>,
        type_tests: &'a mut Vec<TypeTest<'tcx>>,
        all_facts: &'a mut Option<AllFacts>,
    ) -> Self {
        Self {
            mir,
            universal_regions,
            location_table,
            outlives_constraints,
            type_tests,
            all_facts,
        }
    }

    crate fn convert(
        &mut self,
        locations: Locations,
        data: &RegionConstraintData<'tcx>,
    ) {
        debug!("generate: constraints at: {:#?}", locations);
        let RegionConstraintData {
            constraints,
            verifys,
            givens,
        } = data;

        let span = self
            .mir
            .source_info(locations.from_location().unwrap_or(Location::START))
            .span;

        let at_location = locations.at_location().unwrap_or(Location::START);

        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))
                }
            };

            // We have the constraint that `a_vid <= b_vid`. Add
            // `b_vid: a_vid` to our region checker. Note that we
            // reverse direction, because `regioncx` talks about
            // "outlives" (`>=`) whereas the region constraints
            // talk about `<=`.
            self.add_outlives(span, b_vid, a_vid, at_location);

            // In the new analysis, all outlives relations etc
            // "take effect" at the mid point of the statement
            // that requires them, so ignore the `at_location`.
            if let Some(all_facts) = &mut self.all_facts {
                if let Some(from_location) = locations.from_location() {
                    all_facts.outlives.push((
                        b_vid,
                        a_vid,
                        self.location_table.mid_index(from_location),
                    ));
                } else {
                    for location in self.location_table.all_points() {
                        all_facts.outlives.push((b_vid, a_vid, location));
                    }
                }
            }
        }

        for verify in verifys {
            let type_test = self.verify_to_type_test(verify, span, locations);
            self.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().unwrap_or(Location::START);

        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 {
        self.universal_regions.to_region_vid(r)
    }

    fn add_outlives(
        &mut self,
        span: Span,
        sup: ty::RegionVid,
        sub: ty::RegionVid,
        point: Location,
    ) {
        self.outlives_constraints.push(OutlivesConstraint {
            span,
            sub,
            sup,
            point,
            next: None,
        });
    }

    fn add_type_test(&mut self, type_test: TypeTest<'tcx>) {
        self.type_tests.push(type_test);
    }
}