1 //! Experimental types for the trait query interface. The methods
2 //! defined in this module are all based on **canonicalization**,
3 //! which makes a canonical query by replacing unbound inference
4 //! variables and regions, so that results can be reused more broadly.
5 //! The providers for the queries defined here can be found in
8 use crate::error::DropCheckOverflow;
9 use crate::infer::canonical::{Canonical, QueryResponse};
10 use crate::ty::error::TypeError;
11 use crate::ty::subst::GenericArg;
12 use crate::ty::{self, Ty, TyCtxt};
13 use rustc_span::source_map::Span;
16 use crate::ty::fold::TypeFoldable;
17 use crate::ty::{Predicate, Ty, UserType};
20 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, Lift)]
21 #[derive(TypeFoldable, TypeVisitable)]
22 pub struct AscribeUserType<'tcx> {
24 pub user_ty: UserType<'tcx>,
27 impl<'tcx> AscribeUserType<'tcx> {
28 pub fn new(mir_ty: Ty<'tcx>, user_ty: UserType<'tcx>) -> Self {
29 Self { mir_ty, user_ty }
33 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, Lift)]
34 #[derive(TypeFoldable, TypeVisitable)]
40 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, Lift)]
41 #[derive(TypeFoldable, TypeVisitable)]
42 pub struct Subtype<'tcx> {
47 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, Lift)]
48 #[derive(TypeFoldable, TypeVisitable)]
49 pub struct ProvePredicate<'tcx> {
50 pub predicate: Predicate<'tcx>,
53 impl<'tcx> ProvePredicate<'tcx> {
54 pub fn new(predicate: Predicate<'tcx>) -> Self {
55 ProvePredicate { predicate }
59 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable, Lift)]
60 #[derive(TypeFoldable, TypeVisitable)]
61 pub struct Normalize<T> {
65 impl<'tcx, T> Normalize<T>
67 T: fmt::Debug + TypeFoldable<'tcx>,
69 pub fn new(value: T) -> Self {
75 pub type CanonicalProjectionGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, ty::AliasTy<'tcx>>>;
77 pub type CanonicalTyGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, Ty<'tcx>>>;
79 pub type CanonicalPredicateGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, ty::Predicate<'tcx>>>;
81 pub type CanonicalTypeOpAscribeUserTypeGoal<'tcx> =
82 Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::AscribeUserType<'tcx>>>;
84 pub type CanonicalTypeOpEqGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Eq<'tcx>>>;
86 pub type CanonicalTypeOpSubtypeGoal<'tcx> =
87 Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Subtype<'tcx>>>;
89 pub type CanonicalTypeOpProvePredicateGoal<'tcx> =
90 Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::ProvePredicate<'tcx>>>;
92 pub type CanonicalTypeOpNormalizeGoal<'tcx, T> =
93 Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Normalize<T>>>;
95 #[derive(Copy, Clone, Debug, HashStable, PartialEq, Eq)]
96 pub struct NoSolution;
98 pub type Fallible<T> = Result<T, NoSolution>;
100 impl<'tcx> From<TypeError<'tcx>> for NoSolution {
101 fn from(_: TypeError<'tcx>) -> NoSolution {
106 #[derive(Clone, Debug, Default, HashStable, TypeFoldable, TypeVisitable, Lift)]
107 pub struct DropckOutlivesResult<'tcx> {
108 pub kinds: Vec<GenericArg<'tcx>>,
109 pub overflows: Vec<Ty<'tcx>>,
112 impl<'tcx> DropckOutlivesResult<'tcx> {
113 pub fn report_overflows(&self, tcx: TyCtxt<'tcx>, span: Span, ty: Ty<'tcx>) {
114 if let Some(overflow_ty) = self.overflows.get(0) {
115 tcx.sess.emit_err(DropCheckOverflow { span, ty, overflow_ty: *overflow_ty });
119 pub fn into_kinds_reporting_overflows(
124 ) -> Vec<GenericArg<'tcx>> {
125 self.report_overflows(tcx, span, ty);
126 let DropckOutlivesResult { kinds, overflows: _ } = self;
131 /// A set of constraints that need to be satisfied in order for
132 /// a type to be valid for destruction.
133 #[derive(Clone, Debug, HashStable)]
134 pub struct DropckConstraint<'tcx> {
135 /// Types that are required to be alive in order for this
136 /// type to be valid for destruction.
137 pub outlives: Vec<ty::subst::GenericArg<'tcx>>,
139 /// Types that could not be resolved: projections and params.
140 pub dtorck_types: Vec<Ty<'tcx>>,
142 /// If, during the computation of the dtorck constraint, we
143 /// overflow, that gets recorded here. The caller is expected to
145 pub overflows: Vec<Ty<'tcx>>,
148 impl<'tcx> DropckConstraint<'tcx> {
149 pub fn empty() -> DropckConstraint<'tcx> {
150 DropckConstraint { outlives: vec![], dtorck_types: vec![], overflows: vec![] }
154 impl<'tcx> FromIterator<DropckConstraint<'tcx>> for DropckConstraint<'tcx> {
155 fn from_iter<I: IntoIterator<Item = DropckConstraint<'tcx>>>(iter: I) -> Self {
156 let mut result = Self::empty();
158 for DropckConstraint { outlives, dtorck_types, overflows } in iter {
159 result.outlives.extend(outlives);
160 result.dtorck_types.extend(dtorck_types);
161 result.overflows.extend(overflows);
168 #[derive(Debug, HashStable)]
169 pub struct CandidateStep<'tcx> {
170 pub self_ty: Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>,
171 pub autoderefs: usize,
172 /// `true` if the type results from a dereference of a raw pointer.
173 /// when assembling candidates, we include these steps, but not when
174 /// picking methods. This so that if we have `foo: *const Foo` and `Foo` has methods
175 /// `fn by_raw_ptr(self: *const Self)` and `fn by_ref(&self)`, then
176 /// `foo.by_raw_ptr()` will work and `foo.by_ref()` won't.
177 pub from_unsafe_deref: bool,
181 #[derive(Copy, Clone, Debug, HashStable)]
182 pub struct MethodAutoderefStepsResult<'tcx> {
183 /// The valid autoderef steps that could be find.
184 pub steps: &'tcx [CandidateStep<'tcx>],
185 /// If Some(T), a type autoderef reported an error on.
186 pub opt_bad_ty: Option<&'tcx MethodAutoderefBadTy<'tcx>>,
187 /// If `true`, `steps` has been truncated due to reaching the
189 pub reached_recursion_limit: bool,
192 #[derive(Debug, HashStable)]
193 pub struct MethodAutoderefBadTy<'tcx> {
194 pub reached_raw_pointer: bool,
195 pub ty: Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>,
198 /// Result from the `normalize_projection_ty` query.
199 #[derive(Clone, Debug, HashStable, TypeFoldable, TypeVisitable, Lift)]
200 pub struct NormalizationResult<'tcx> {
201 /// Result of normalization.
202 pub normalized_ty: Ty<'tcx>,
205 /// Outlives bounds are relationships between generic parameters,
206 /// whether they both be regions (`'a: 'b`) or whether types are
207 /// involved (`T: 'a`). These relationships can be extracted from the
208 /// full set of predicates we understand or also from types (in which
209 /// case they are called implied bounds). They are fed to the
210 /// `OutlivesEnv` which in turn is supplied to the region checker and
211 /// other parts of the inference system.
212 #[derive(Clone, Debug, TypeFoldable, TypeVisitable, Lift, HashStable)]
213 pub enum OutlivesBound<'tcx> {
214 RegionSubRegion(ty::Region<'tcx>, ty::Region<'tcx>),
215 RegionSubParam(ty::Region<'tcx>, ty::ParamTy),
216 RegionSubAlias(ty::Region<'tcx>, ty::AliasTy<'tcx>),