Move opaque type cache into InferCtxt

Author: oli-obk

compiler/rustc_infer/src/infer/mod.rs

@@ -4,6 +4,7 @@ pub use self::RegionVariableOrigin::*;
 pub use self::SubregionOrigin::*;
 pub use self::ValuePairs::*;
 
+use self::opaque_types::OpaqueTypeDecl;
 pub(crate) use self::undo_log::{InferCtxtUndoLogs, Snapshot, UndoLog};
 
 use crate::traits::{self, ObligationCause, PredicateObligations, TraitEngine};
@@ -12,6 +13,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::undo_log::Rollback;
 use rustc_data_structures::unify as ut;
+use rustc_data_structures::vec_map::VecMap;
 use rustc_errors::DiagnosticBuilder;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -25,6 +27,7 @@ use rustc_middle::ty::fold::{TypeFoldable, TypeFolder};
 use rustc_middle::ty::relate::RelateResult;
 use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, SubstsRef};
 pub use rustc_middle::ty::IntVarValue;
+use rustc_middle::ty::OpaqueTypeKey;
 use rustc_middle::ty::{self, GenericParamDefKind, InferConst, Ty, TyCtxt};
 use rustc_middle::ty::{ConstVid, FloatVid, IntVid, TyVid};
 use rustc_session::config::BorrowckMode;
@@ -59,6 +62,7 @@ pub mod lattice;
 mod lexical_region_resolve;
 mod lub;
 pub mod nll_relate;
+pub mod opaque_types;
 pub mod outlives;
 pub mod region_constraints;
 pub mod resolve;
@@ -191,6 +195,19 @@ pub struct InferCtxtInner<'tcx> {
     region_obligations: Vec<(hir::HirId, RegionObligation<'tcx>)>,
 
     undo_log: InferCtxtUndoLogs<'tcx>,
+
+    // Opaque types found in explicit return types and their
+    // associated fresh inference variable. Writeback resolves these
+    // variables to get the concrete type, which can be used to
+    // 'de-opaque' OpaqueTypeDecl, after typeck is done with all functions.
+    pub opaque_types: VecMap<OpaqueTypeKey<'tcx>, OpaqueTypeDecl<'tcx>>,
+
+    /// A map from inference variables created from opaque
+    /// type instantiations (`ty::Infer`) to the actual opaque
+    /// type (`ty::Opaque`). Used during fallback to map unconstrained
+    /// opaque type inference variables to their corresponding
+    /// opaque type.
+    pub opaque_types_vars: FxHashMap<Ty<'tcx>, Ty<'tcx>>,
 }
 
 impl<'tcx> InferCtxtInner<'tcx> {
@@ -204,6 +221,8 @@ impl<'tcx> InferCtxtInner<'tcx> {
             float_unification_storage: ut::UnificationTableStorage::new(),
             region_constraint_storage: Some(RegionConstraintStorage::new()),
             region_obligations: vec![],
+            opaque_types: Default::default(),
+            opaque_types_vars: Default::default(),
         }
     }
 

compiler/rustc_infer/src/infer/opaque_types.rs

@@ -0,0 +1,70 @@
+use rustc_data_structures::vec_map::VecMap;
+use rustc_hir as hir;
+use rustc_middle::ty::{OpaqueTypeKey, Ty};
+use rustc_span::Span;
+
+pub type OpaqueTypeMap<'tcx> = VecMap<OpaqueTypeKey<'tcx>, OpaqueTypeDecl<'tcx>>;
+
+/// Information about the opaque types whose values we
+/// are inferring in this function (these are the `impl Trait` that
+/// appear in the return type).
+#[derive(Copy, Clone, Debug)]
+pub struct OpaqueTypeDecl<'tcx> {
+    /// The opaque type (`ty::Opaque`) for this declaration.
+    pub opaque_type: Ty<'tcx>,
+
+    /// The span of this particular definition of the opaque type. So
+    /// for example:
+    ///
+    /// ```ignore (incomplete snippet)
+    /// type Foo = impl Baz;
+    /// fn bar() -> Foo {
+    /// //          ^^^ This is the span we are looking for!
+    /// }
+    /// ```
+    ///
+    /// In cases where the fn returns `(impl Trait, impl Trait)` or
+    /// other such combinations, the result is currently
+    /// over-approximated, but better than nothing.
+    pub definition_span: Span,
+
+    /// The type variable that represents the value of the opaque type
+    /// that we require. In other words, after we compile this function,
+    /// we will be created a constraint like:
+    ///
+    ///     Foo<'a, T> = ?C
+    ///
+    /// where `?C` is the value of this type variable. =) It may
+    /// naturally refer to the type and lifetime parameters in scope
+    /// in this function, though ultimately it should only reference
+    /// those that are arguments to `Foo` in the constraint above. (In
+    /// other words, `?C` should not include `'b`, even though it's a
+    /// lifetime parameter on `foo`.)
+    pub concrete_ty: Ty<'tcx>,
+
+    /// Returns `true` if the `impl Trait` bounds include region bounds.
+    /// For example, this would be true for:
+    ///
+    ///     fn foo<'a, 'b, 'c>() -> impl Trait<'c> + 'a + 'b
+    ///
+    /// but false for:
+    ///
+    ///     fn foo<'c>() -> impl Trait<'c>
+    ///
+    /// unless `Trait` was declared like:
+    ///
+    ///     trait Trait<'c>: 'c
+    ///
+    /// in which case it would be true.
+    ///
+    /// This is used during regionck to decide whether we need to
+    /// impose any additional constraints to ensure that region
+    /// variables in `concrete_ty` wind up being constrained to
+    /// something from `substs` (or, at minimum, things that outlive
+    /// the fn body). (Ultimately, writeback is responsible for this
+    /// check.)
+    pub has_required_region_bounds: bool,
+
+    /// The origin of the opaque type.
+    pub origin: hir::OpaqueTyOrigin,
+}

compiler/rustc_trait_selection/src/opaque_types.rs

@@ -2,11 +2,11 @@ use crate::infer::InferCtxtExt as _;
 use crate::traits::{self, ObligationCause, PredicateObligation};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lrc;
-use rustc_data_structures::vec_map::VecMap;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_infer::infer::error_reporting::unexpected_hidden_region_diagnostic;
 use rustc_infer::infer::free_regions::FreeRegionRelations;
+use rustc_infer::infer::opaque_types::{OpaqueTypeDecl, OpaqueTypeMap};
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::{self, InferCtxt, InferOk};
 use rustc_middle::ty::fold::{BottomUpFolder, TypeFoldable, TypeFolder, TypeVisitor};
@@ -16,72 +16,6 @@ use rustc_span::Span;
 
 use std::ops::ControlFlow;
 
-pub type OpaqueTypeMap<'tcx> = VecMap<OpaqueTypeKey<'tcx>, OpaqueTypeDecl<'tcx>>;
-
-/// Information about the opaque types whose values we
-/// are inferring in this function (these are the `impl Trait` that
-/// appear in the return type).
-#[derive(Copy, Clone, Debug)]
-pub struct OpaqueTypeDecl<'tcx> {
-    /// The opaque type (`ty::Opaque`) for this declaration.
-    pub opaque_type: Ty<'tcx>,
-
-    /// The span of this particular definition of the opaque type. So
-    /// for example:
-    ///
-    /// ```ignore (incomplete snippet)
-    /// type Foo = impl Baz;
-    /// fn bar() -> Foo {
-    /// //          ^^^ This is the span we are looking for!
-    /// }
-    /// ```
-    ///
-    /// In cases where the fn returns `(impl Trait, impl Trait)` or
-    /// other such combinations, the result is currently
-    /// over-approximated, but better than nothing.
-    pub definition_span: Span,
-
-    /// The type variable that represents the value of the opaque type
-    /// that we require. In other words, after we compile this function,
-    /// we will be created a constraint like:
-    ///
-    ///     Foo<'a, T> = ?C
-    ///
-    /// where `?C` is the value of this type variable. =) It may
-    /// naturally refer to the type and lifetime parameters in scope
-    /// in this function, though ultimately it should only reference
-    /// those that are arguments to `Foo` in the constraint above. (In
-    /// other words, `?C` should not include `'b`, even though it's a
-    /// lifetime parameter on `foo`.)
-    pub concrete_ty: Ty<'tcx>,
-
-    /// Returns `true` if the `impl Trait` bounds include region bounds.
-    /// For example, this would be true for:
-    ///
-    ///     fn foo<'a, 'b, 'c>() -> impl Trait<'c> + 'a + 'b
-    ///
-    /// but false for:
-    ///
-    ///     fn foo<'c>() -> impl Trait<'c>
-    ///
-    /// unless `Trait` was declared like:
-    ///
-    ///     trait Trait<'c>: 'c
-    ///
-    /// in which case it would be true.
-    ///
-    /// This is used during regionck to decide whether we need to
-    /// impose any additional constraints to ensure that region
-    /// variables in `concrete_ty` wind up being constrained to
-    /// something from `substs` (or, at minimum, things that outlive
-    /// the fn body). (Ultimately, writeback is responsible for this
-    /// check.)
-    pub has_required_region_bounds: bool,
-
-    /// The origin of the opaque type.
-    pub origin: hir::OpaqueTyOrigin,
-}
-
 /// Whether member constraints should be generated for all opaque types
 #[derive(Debug)]
 pub enum GenerateMemberConstraints {
@@ -105,11 +39,7 @@ pub trait InferCtxtExt<'tcx> {
         value_span: Span,
     ) -> InferOk<'tcx, (T, OpaqueTypeMap<'tcx>)>;
 
-    fn constrain_opaque_types<FRR: FreeRegionRelations<'tcx>>(
-        &self,
-        opaque_types: &OpaqueTypeMap<'tcx>,
-        free_region_relations: &FRR,
-    );
+    fn constrain_opaque_types<FRR: FreeRegionRelations<'tcx>>(&self, free_region_relations: &FRR);
 
     fn constrain_opaque_type<FRR: FreeRegionRelations<'tcx>>(
         &self,
@@ -350,12 +280,9 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
     /// - `opaque_types` -- the map produced by `instantiate_opaque_types`
     /// - `free_region_relations` -- something that can be used to relate
     ///   the free regions (`'a`) that appear in the impl trait.
-    fn constrain_opaque_types<FRR: FreeRegionRelations<'tcx>>(
-        &self,
-        opaque_types: &OpaqueTypeMap<'tcx>,
-        free_region_relations: &FRR,
-    ) {
-        for &(opaque_type_key, opaque_defn) in opaque_types {
+    fn constrain_opaque_types<FRR: FreeRegionRelations<'tcx>>(&self, free_region_relations: &FRR) {
+        let opaque_types = self.inner.borrow().opaque_types.clone();
+        for (opaque_type_key, opaque_defn) in opaque_types {
             self.constrain_opaque_type(
                 opaque_type_key,
                 &opaque_defn,

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -385,8 +385,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 value_span,
             ));
 
-        let mut opaque_types = self.opaque_types.borrow_mut();
-        let mut opaque_types_vars = self.opaque_types_vars.borrow_mut();
+        let mut infcx = self.infcx.inner.borrow_mut();
 
         for (ty, decl) in opaque_type_map {
             if let Some(feature) = feature {
@@ -402,8 +401,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     }
                 }
             }
-            let _ = opaque_types.insert(ty, decl);
-            let _ = opaque_types_vars.insert(decl.concrete_ty, decl.opaque_type);
+            let _ = infcx.opaque_types.insert(ty, decl);
+            let _ = infcx.opaque_types_vars.insert(decl.concrete_ty, decl.opaque_type);
         }
 
         value
@@ -726,7 +725,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // We treat this as a non-defining use by making the inference
                 // variable fall back to the opaque type itself.
                 if let FallbackMode::All = mode {
-                    if let Some(opaque_ty) = self.opaque_types_vars.borrow().get(ty) {
+                    if let Some(opaque_ty) = self.infcx.inner.borrow().opaque_types_vars.get(ty) {
                         debug!(
                             "fallback_if_possible: falling back opaque type var {:?} to {:?}",
                             ty, opaque_ty

compiler/rustc_typeck/src/check/inherited.rs

@@ -1,18 +1,15 @@
 use super::callee::DeferredCallResolution;
 use super::MaybeInProgressTables;
 
-use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::vec_map::VecMap;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefIdMap, LocalDefId};
 use rustc_hir::HirIdMap;
 use rustc_infer::infer;
 use rustc_infer::infer::{InferCtxt, InferOk, TyCtxtInferExt};
 use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::{self, OpaqueTypeKey, Ty, TyCtxt};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::{self, Span};
 use rustc_trait_selection::infer::InferCtxtExt as _;
-use rustc_trait_selection::opaque_types::OpaqueTypeDecl;
 use rustc_trait_selection::traits::{self, ObligationCause, TraitEngine, TraitEngineExt};
 
 use std::cell::RefCell;
@@ -55,19 +52,6 @@ pub struct Inherited<'a, 'tcx> {
     pub(super) deferred_generator_interiors:
         RefCell<Vec<(hir::BodyId, Ty<'tcx>, hir::GeneratorKind)>>,
 
-    // Opaque types found in explicit return types and their
-    // associated fresh inference variable. Writeback resolves these
-    // variables to get the concrete type, which can be used to
-    // 'de-opaque' OpaqueTypeDecl, after typeck is done with all functions.
-    pub(super) opaque_types: RefCell<VecMap<OpaqueTypeKey<'tcx>, OpaqueTypeDecl<'tcx>>>,
-
-    /// A map from inference variables created from opaque
-    /// type instantiations (`ty::Infer`) to the actual opaque
-    /// type (`ty::Opaque`). Used during fallback to map unconstrained
-    /// opaque type inference variables to their corresponding
-    /// opaque type.
-    pub(super) opaque_types_vars: RefCell<FxHashMap<Ty<'tcx>, Ty<'tcx>>>,
-
     pub(super) body_id: Option<hir::BodyId>,
 }
 
@@ -124,8 +108,6 @@ impl Inherited<'a, 'tcx> {
             deferred_call_resolutions: RefCell::new(Default::default()),
             deferred_cast_checks: RefCell::new(Vec::new()),
             deferred_generator_interiors: RefCell::new(Vec::new()),
-            opaque_types: RefCell::new(Default::default()),
-            opaque_types_vars: RefCell::new(Default::default()),
             body_id,
         }
     }

compiler/rustc_typeck/src/check/regionck.rs

@@ -291,10 +291,7 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
         self.visit_body(body);
         self.visit_region_obligations(body_id.hir_id);
 
-        self.constrain_opaque_types(
-            &self.fcx.opaque_types.borrow(),
-            self.outlives_environment.free_region_map(),
-        );
+        self.constrain_opaque_types(self.outlives_environment.free_region_map());
     }
 
     fn visit_region_obligations(&mut self, hir_id: hir::HirId) {

compiler/rustc_typeck/src/check/writeback.rs

@@ -498,7 +498,8 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
     }
 
     fn visit_opaque_types(&mut self, span: Span) {
-        for &(opaque_type_key, opaque_defn) in self.fcx.opaque_types.borrow().iter() {
+        let opaque_types = self.fcx.infcx.inner.borrow().opaque_types.clone();
+        for (opaque_type_key, opaque_defn) in opaque_types {
             let hir_id =
                 self.tcx().hir().local_def_id_to_hir_id(opaque_type_key.def_id.expect_local());
             let instantiated_ty = self.resolve(opaque_defn.concrete_ty, &hir_id);