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
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
//! Experimental types for the trait query interface. The methods
//! defined in this module are all based on **canonicalization**,
//! which makes a canonical query by replacing unbound inference
//! variables and regions, so that results can be reused more broadly.
//! The providers for the queries defined here can be found in
//! `rustc_traits`.

use crate::ich::StableHashingContext;
use crate::infer::canonical::{Canonical, QueryResponse};
use crate::ty::error::TypeError;
use crate::ty::subst::GenericArg;
use crate::ty::{self, Ty, TyCtxt};

use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_data_structures::sync::Lrc;
use rustc_errors::struct_span_err;
use rustc_span::source_map::Span;
use std::iter::FromIterator;
use std::mem;

pub mod type_op {
    use crate::ty::fold::TypeFoldable;
    use crate::ty::subst::UserSubsts;
    use crate::ty::{Predicate, Ty};
    use rustc_hir::def_id::DefId;
    use std::fmt;

    #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, TypeFoldable, Lift)]
    pub struct AscribeUserType<'tcx> {
        pub mir_ty: Ty<'tcx>,
        pub def_id: DefId,
        pub user_substs: UserSubsts<'tcx>,
    }

    impl<'tcx> AscribeUserType<'tcx> {
        pub fn new(mir_ty: Ty<'tcx>, def_id: DefId, user_substs: UserSubsts<'tcx>) -> Self {
            Self { mir_ty, def_id, user_substs }
        }
    }

    #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, TypeFoldable, Lift)]
    pub struct Eq<'tcx> {
        pub a: Ty<'tcx>,
        pub b: Ty<'tcx>,
    }

    #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, TypeFoldable, Lift)]
    pub struct Subtype<'tcx> {
        pub sub: Ty<'tcx>,
        pub sup: Ty<'tcx>,
    }

    #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, TypeFoldable, Lift)]
    pub struct ProvePredicate<'tcx> {
        pub predicate: Predicate<'tcx>,
    }

    impl<'tcx> ProvePredicate<'tcx> {
        pub fn new(predicate: Predicate<'tcx>) -> Self {
            ProvePredicate { predicate }
        }
    }

    #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, TypeFoldable, Lift)]
    pub struct Normalize<T> {
        pub value: T,
    }

    impl<'tcx, T> Normalize<T>
    where
        T: fmt::Debug + TypeFoldable<'tcx>,
    {
        pub fn new(value: T) -> Self {
            Self { value }
        }
    }
}

pub type CanonicalProjectionGoal<'tcx> =
    Canonical<'tcx, ty::ParamEnvAnd<'tcx, ty::ProjectionTy<'tcx>>>;

pub type CanonicalTyGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, Ty<'tcx>>>;

pub type CanonicalPredicateGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, ty::Predicate<'tcx>>>;

pub type CanonicalTypeOpAscribeUserTypeGoal<'tcx> =
    Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::AscribeUserType<'tcx>>>;

pub type CanonicalTypeOpEqGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Eq<'tcx>>>;

pub type CanonicalTypeOpSubtypeGoal<'tcx> =
    Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Subtype<'tcx>>>;

pub type CanonicalTypeOpProvePredicateGoal<'tcx> =
    Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::ProvePredicate<'tcx>>>;

pub type CanonicalTypeOpNormalizeGoal<'tcx, T> =
    Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Normalize<T>>>;

#[derive(Clone, Debug, HashStable)]
pub struct NoSolution;

pub type Fallible<T> = Result<T, NoSolution>;

impl<'tcx> From<TypeError<'tcx>> for NoSolution {
    fn from(_: TypeError<'tcx>) -> NoSolution {
        NoSolution
    }
}

#[derive(Clone, Debug, Default, HashStable, TypeFoldable, Lift)]
pub struct DropckOutlivesResult<'tcx> {
    pub kinds: Vec<GenericArg<'tcx>>,
    pub overflows: Vec<Ty<'tcx>>,
}

impl<'tcx> DropckOutlivesResult<'tcx> {
    pub fn report_overflows(&self, tcx: TyCtxt<'tcx>, span: Span, ty: Ty<'tcx>) {
        if let Some(overflow_ty) = self.overflows.get(0) {
            let mut err = struct_span_err!(
                tcx.sess,
                span,
                E0320,
                "overflow while adding drop-check rules for {}",
                ty,
            );
            err.note(&format!("overflowed on {}", overflow_ty));
            err.emit();
        }
    }

    pub fn into_kinds_reporting_overflows(
        self,
        tcx: TyCtxt<'tcx>,
        span: Span,
        ty: Ty<'tcx>,
    ) -> Vec<GenericArg<'tcx>> {
        self.report_overflows(tcx, span, ty);
        let DropckOutlivesResult { kinds, overflows: _ } = self;
        kinds
    }
}

/// A set of constraints that need to be satisfied in order for
/// a type to be valid for destruction.
#[derive(Clone, Debug, HashStable)]
pub struct DtorckConstraint<'tcx> {
    /// Types that are required to be alive in order for this
    /// type to be valid for destruction.
    pub outlives: Vec<ty::subst::GenericArg<'tcx>>,

    /// Types that could not be resolved: projections and params.
    pub dtorck_types: Vec<Ty<'tcx>>,

    /// If, during the computation of the dtorck constraint, we
    /// overflow, that gets recorded here. The caller is expected to
    /// report an error.
    pub overflows: Vec<Ty<'tcx>>,
}

impl<'tcx> DtorckConstraint<'tcx> {
    pub fn empty() -> DtorckConstraint<'tcx> {
        DtorckConstraint { outlives: vec![], dtorck_types: vec![], overflows: vec![] }
    }
}

impl<'tcx> FromIterator<DtorckConstraint<'tcx>> for DtorckConstraint<'tcx> {
    fn from_iter<I: IntoIterator<Item = DtorckConstraint<'tcx>>>(iter: I) -> Self {
        let mut result = Self::empty();

        for DtorckConstraint { outlives, dtorck_types, overflows } in iter {
            result.outlives.extend(outlives);
            result.dtorck_types.extend(dtorck_types);
            result.overflows.extend(overflows);
        }

        result
    }
}

#[derive(Debug, HashStable)]
pub struct CandidateStep<'tcx> {
    pub self_ty: Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>,
    pub autoderefs: usize,
    /// `true` if the type results from a dereference of a raw pointer.
    /// when assembling candidates, we include these steps, but not when
    /// picking methods. This so that if we have `foo: *const Foo` and `Foo` has methods
    /// `fn by_raw_ptr(self: *const Self)` and `fn by_ref(&self)`, then
    /// `foo.by_raw_ptr()` will work and `foo.by_ref()` won't.
    pub from_unsafe_deref: bool,
    pub unsize: bool,
}

#[derive(Clone, Debug, HashStable)]
pub struct MethodAutoderefStepsResult<'tcx> {
    /// The valid autoderef steps that could be find.
    pub steps: Lrc<Vec<CandidateStep<'tcx>>>,
    /// If Some(T), a type autoderef reported an error on.
    pub opt_bad_ty: Option<Lrc<MethodAutoderefBadTy<'tcx>>>,
    /// If `true`, `steps` has been truncated due to reaching the
    /// recursion limit.
    pub reached_recursion_limit: bool,
}

#[derive(Debug, HashStable)]
pub struct MethodAutoderefBadTy<'tcx> {
    pub reached_raw_pointer: bool,
    pub ty: Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>,
}

/// Result from the `normalize_projection_ty` query.
#[derive(Clone, Debug, HashStable, TypeFoldable, Lift)]
pub struct NormalizationResult<'tcx> {
    /// Result of normalization.
    pub normalized_ty: Ty<'tcx>,
}

/// Outlives bounds are relationships between generic parameters,
/// whether they both be regions (`'a: 'b`) or whether types are
/// involved (`T: 'a`). These relationships can be extracted from the
/// full set of predicates we understand or also from types (in which
/// case they are called implied bounds). They are fed to the
/// `OutlivesEnv` which in turn is supplied to the region checker and
/// other parts of the inference system.
#[derive(Clone, Debug, TypeFoldable, Lift)]
pub enum OutlivesBound<'tcx> {
    RegionSubRegion(ty::Region<'tcx>, ty::Region<'tcx>),
    RegionSubParam(ty::Region<'tcx>, ty::ParamTy),
    RegionSubProjection(ty::Region<'tcx>, ty::ProjectionTy<'tcx>),
}

impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for OutlivesBound<'tcx> {
    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
        mem::discriminant(self).hash_stable(hcx, hasher);
        match *self {
            OutlivesBound::RegionSubRegion(ref a, ref b) => {
                a.hash_stable(hcx, hasher);
                b.hash_stable(hcx, hasher);
            }
            OutlivesBound::RegionSubParam(ref a, ref b) => {
                a.hash_stable(hcx, hasher);
                b.hash_stable(hcx, hasher);
            }
            OutlivesBound::RegionSubProjection(ref a, ref b) => {
                a.hash_stable(hcx, hasher);
                b.hash_stable(hcx, hasher);
            }
        }
    }
}