Auto merge of #148170 - lcnr:opaques-early-binder, r=BoxyUwU

split definition and use site hidden tys

Tracking this implicitly is kinda messy and easy to get wrong.

r? `@BoxyUwU`

Author: bors

compiler/rustc_borrowck/src/lib.rs

@@ -119,7 +119,7 @@ pub fn provide(providers: &mut Providers) {
 fn mir_borrowck(
     tcx: TyCtxt<'_>,
     def: LocalDefId,
-) -> Result<&DefinitionSiteHiddenTypes<'_>, ErrorGuaranteed> {
+) -> Result<&FxIndexMap<LocalDefId, ty::DefinitionSiteHiddenType<'_>>, ErrorGuaranteed> {
     assert!(!tcx.is_typeck_child(def.to_def_id()));
     let (input_body, _) = tcx.mir_promoted(def);
     debug!("run query mir_borrowck: {}", tcx.def_path_str(def));
@@ -130,7 +130,7 @@ fn mir_borrowck(
         Err(guar)
     } else if input_body.should_skip() {
         debug!("Skipping borrowck because of injected body");
-        let opaque_types = DefinitionSiteHiddenTypes(Default::default());
+        let opaque_types = Default::default();
         Ok(tcx.arena.alloc(opaque_types))
     } else {
         let mut root_cx = BorrowCheckRootCtxt::new(tcx, def, None);

compiler/rustc_borrowck/src/region_infer/opaque_types/mod.rs

@@ -8,11 +8,11 @@ use rustc_infer::infer::outlives::env::RegionBoundPairs;
 use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin, OpaqueTypeStorageEntries};
 use rustc_infer::traits::ObligationCause;
 use rustc_macros::extension;
-use rustc_middle::mir::{Body, ConstraintCategory, DefinitionSiteHiddenTypes};
+use rustc_middle::mir::{Body, ConstraintCategory};
 use rustc_middle::ty::{
-    self, DefiningScopeKind, EarlyBinder, FallibleTypeFolder, GenericArg, GenericArgsRef,
-    OpaqueHiddenType, OpaqueTypeKey, Region, RegionVid, Ty, TyCtxt, TypeFoldable,
-    TypeSuperFoldable, TypeVisitableExt, fold_regions,
+    self, DefiningScopeKind, DefinitionSiteHiddenType, FallibleTypeFolder, GenericArg,
+    GenericArgsRef, OpaqueTypeKey, ProvisionalHiddenType, Region, RegionVid, Ty, TyCtxt,
+    TypeFoldable, TypeSuperFoldable, TypeVisitableExt, fold_regions,
 };
 use rustc_mir_dataflow::points::DenseLocationMap;
 use rustc_span::Span;
@@ -48,7 +48,7 @@ pub(crate) enum DeferredOpaqueTypeError<'tcx> {
         /// The opaque type.
         opaque_type_key: OpaqueTypeKey<'tcx>,
         /// The hidden type containing the member region.
-        hidden_type: OpaqueHiddenType<'tcx>,
+        hidden_type: ProvisionalHiddenType<'tcx>,
         /// The unexpected region.
         member_region: Region<'tcx>,
     },
@@ -67,7 +67,7 @@ pub(crate) fn clone_and_resolve_opaque_types<'tcx>(
     infcx: &BorrowckInferCtxt<'tcx>,
     universal_region_relations: &Frozen<UniversalRegionRelations<'tcx>>,
     constraints: &mut MirTypeckRegionConstraints<'tcx>,
-) -> (OpaqueTypeStorageEntries, Vec<(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)>) {
+) -> (OpaqueTypeStorageEntries, Vec<(OpaqueTypeKey<'tcx>, ProvisionalHiddenType<'tcx>)>) {
     let opaque_types = infcx.clone_opaque_types();
     let opaque_types_storage_num_entries = infcx.inner.borrow_mut().opaque_types().num_entries();
     let opaque_types = opaque_types
@@ -131,27 +131,26 @@ fn nll_var_to_universal_region<'tcx>(
 /// and errors if we end up with distinct hidden types.
 fn add_hidden_type<'tcx>(
     tcx: TyCtxt<'tcx>,
-    hidden_types: &mut DefinitionSiteHiddenTypes<'tcx>,
+    hidden_types: &mut FxIndexMap<LocalDefId, ty::DefinitionSiteHiddenType<'tcx>>,
     def_id: LocalDefId,
-    hidden_ty: OpaqueHiddenType<'tcx>,
+    hidden_ty: ty::DefinitionSiteHiddenType<'tcx>,
 ) {
     // Sometimes two opaque types are the same only after we remap the generic parameters
     // back to the opaque type definition. E.g. we may have `OpaqueType<X, Y>` mapped to
     // `(X, Y)` and `OpaqueType<Y, X>` mapped to `(Y, X)`, and those are the same, but we
     // only know that once we convert the generic parameters to those of the opaque type.
-    if let Some(prev) = hidden_types.0.get_mut(&def_id) {
-        if prev.ty != hidden_ty.ty {
-            let guar = hidden_ty.ty.error_reported().err().unwrap_or_else(|| {
-                let (Ok(e) | Err(e)) = prev.build_mismatch_error(&hidden_ty, tcx).map(|d| d.emit());
-                e
-            });
-            prev.ty = Ty::new_error(tcx, guar);
+    if let Some(prev) = hidden_types.get_mut(&def_id) {
+        if prev.ty == hidden_ty.ty {
+            // Pick a better span if there is one.
+            // FIXME(oli-obk): collect multiple spans for better diagnostics down the road.
+            prev.span = prev.span.substitute_dummy(hidden_ty.span);
+        } else {
+            let (Ok(guar) | Err(guar)) =
+                prev.build_mismatch_error(&hidden_ty, tcx).map(|d| d.emit());
+            *prev = ty::DefinitionSiteHiddenType::new_error(tcx, guar);
         }
-        // Pick a better span if there is one.
-        // FIXME(oli-obk): collect multiple spans for better diagnostics down the road.
-        prev.span = prev.span.substitute_dummy(hidden_ty.span);
     } else {
-        hidden_types.0.insert(def_id, hidden_ty);
+        hidden_types.insert(def_id, hidden_ty);
     }
 }
 
@@ -162,7 +161,7 @@ struct DefiningUse<'tcx> {
     /// to interact with code outside of `rustc_borrowck`.
     opaque_type_key: OpaqueTypeKey<'tcx>,
     arg_regions: Vec<RegionVid>,
-    hidden_type: OpaqueHiddenType<'tcx>,
+    hidden_type: ProvisionalHiddenType<'tcx>,
 }
 
 /// This computes the actual hidden types of the opaque types and maps them to their
@@ -181,8 +180,8 @@ pub(crate) fn compute_definition_site_hidden_types<'tcx>(
     universal_region_relations: &Frozen<UniversalRegionRelations<'tcx>>,
     constraints: &MirTypeckRegionConstraints<'tcx>,
     location_map: Rc<DenseLocationMap>,
-    hidden_types: &mut DefinitionSiteHiddenTypes<'tcx>,
-    opaque_types: &[(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)],
+    hidden_types: &mut FxIndexMap<LocalDefId, ty::DefinitionSiteHiddenType<'tcx>>,
+    opaque_types: &[(OpaqueTypeKey<'tcx>, ProvisionalHiddenType<'tcx>)],
 ) -> Vec<DeferredOpaqueTypeError<'tcx>> {
     let mut errors = Vec::new();
     // When computing the hidden type we need to track member constraints.
@@ -216,8 +215,8 @@ pub(crate) fn compute_definition_site_hidden_types<'tcx>(
 #[instrument(level = "debug", skip_all, ret)]
 fn collect_defining_uses<'tcx>(
     rcx: &mut RegionCtxt<'_, 'tcx>,
-    hidden_types: &mut DefinitionSiteHiddenTypes<'tcx>,
-    opaque_types: &[(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)],
+    hidden_types: &mut FxIndexMap<LocalDefId, ty::DefinitionSiteHiddenType<'tcx>>,
+    opaque_types: &[(OpaqueTypeKey<'tcx>, ProvisionalHiddenType<'tcx>)],
     errors: &mut Vec<DeferredOpaqueTypeError<'tcx>>,
 ) -> Vec<DefiningUse<'tcx>> {
     let infcx = rcx.infcx;
@@ -240,7 +239,7 @@ fn collect_defining_uses<'tcx>(
                         infcx.tcx,
                         hidden_types,
                         opaque_type_key.def_id,
-                        OpaqueHiddenType::new_error(infcx.tcx, guar),
+                        DefinitionSiteHiddenType::new_error(infcx.tcx, guar),
                     ),
                     _ => debug!(?non_nll_opaque_type_key, ?err, "ignoring non-defining use"),
                 }
@@ -276,7 +275,7 @@ fn collect_defining_uses<'tcx>(
 #[instrument(level = "debug", skip(rcx, hidden_types, defining_uses, errors))]
 fn compute_definition_site_hidden_types_from_defining_uses<'tcx>(
     rcx: &RegionCtxt<'_, 'tcx>,
-    hidden_types: &mut DefinitionSiteHiddenTypes<'tcx>,
+    hidden_types: &mut FxIndexMap<LocalDefId, ty::DefinitionSiteHiddenType<'tcx>>,
     defining_uses: &[DefiningUse<'tcx>],
     errors: &mut Vec<DeferredOpaqueTypeError<'tcx>>,
 ) {
@@ -303,29 +302,28 @@ fn compute_definition_site_hidden_types_from_defining_uses<'tcx>(
                         hidden_type.span,
                         "opaque type with non-universal region args",
                     );
-                    ty::OpaqueHiddenType::new_error(tcx, guar)
+                    ty::ProvisionalHiddenType::new_error(tcx, guar)
                 }
             };
 
         // Now that we mapped the member regions to their final value,
         // map the arguments of the opaque type key back to the parameters
         // of the opaque type definition.
-        let ty = infcx
+        let hidden_type = infcx
             .infer_opaque_definition_from_instantiation(opaque_type_key, hidden_type)
             .unwrap_or_else(|_| {
-                Ty::new_error_with_message(
-                    rcx.infcx.tcx,
-                    hidden_type.span,
-                    "deferred invalid opaque type args",
-                )
+                let guar = tcx
+                    .dcx()
+                    .span_delayed_bug(hidden_type.span, "deferred invalid opaque type args");
+                DefinitionSiteHiddenType::new_error(tcx, guar)
             });
 
         // Sometimes, when the hidden type is an inference variable, it can happen that
         // the hidden type becomes the opaque type itself. In this case, this was an opaque
         // usage of the opaque type and we can ignore it. This check is mirrored in typeck's
         // writeback.
         if !rcx.infcx.tcx.use_typing_mode_borrowck() {
-            if let ty::Alias(ty::Opaque, alias_ty) = ty.kind()
+            if let ty::Alias(ty::Opaque, alias_ty) = hidden_type.ty.skip_binder().kind()
                 && alias_ty.def_id == opaque_type_key.def_id.to_def_id()
                 && alias_ty.args == opaque_type_key.args
             {
@@ -357,12 +355,7 @@ fn compute_definition_site_hidden_types_from_defining_uses<'tcx>(
                 },
             ));
         }
-        add_hidden_type(
-            tcx,
-            hidden_types,
-            opaque_type_key.def_id,
-            OpaqueHiddenType { span: hidden_type.span, ty },
-        );
+        add_hidden_type(tcx, hidden_types, opaque_type_key.def_id, hidden_type);
     }
 }
 
@@ -495,14 +488,13 @@ pub(crate) fn apply_definition_site_hidden_types<'tcx>(
     region_bound_pairs: &RegionBoundPairs<'tcx>,
     known_type_outlives_obligations: &[ty::PolyTypeOutlivesPredicate<'tcx>],
     constraints: &mut MirTypeckRegionConstraints<'tcx>,
-    hidden_types: &mut DefinitionSiteHiddenTypes<'tcx>,
-    opaque_types: &[(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)],
+    hidden_types: &mut FxIndexMap<LocalDefId, ty::DefinitionSiteHiddenType<'tcx>>,
+    opaque_types: &[(OpaqueTypeKey<'tcx>, ProvisionalHiddenType<'tcx>)],
 ) -> Vec<DeferredOpaqueTypeError<'tcx>> {
     let tcx = infcx.tcx;
     let mut errors = Vec::new();
     for &(key, hidden_type) in opaque_types {
-        let Some(expected) = hidden_types.0.get(&key.def_id).map(|ty| EarlyBinder::bind(*ty))
-        else {
+        let Some(expected) = hidden_types.get(&key.def_id) else {
             if !tcx.use_typing_mode_borrowck() {
                 if let ty::Alias(ty::Opaque, alias_ty) = hidden_type.ty.kind()
                     && alias_ty.def_id == key.def_id.to_def_id()
@@ -521,20 +513,26 @@ pub(crate) fn apply_definition_site_hidden_types<'tcx>(
                 hidden_type.span,
                 "non-defining use in the defining scope with no defining uses",
             );
-            add_hidden_type(tcx, hidden_types, key.def_id, OpaqueHiddenType::new_error(tcx, guar));
+            add_hidden_type(
+                tcx,
+                hidden_types,
+                key.def_id,
+                DefinitionSiteHiddenType::new_error(tcx, guar),
+            );
             continue;
         };
 
         // We erase all non-member region of the opaque and need to treat these as existentials.
-        let expected = ty::fold_regions(tcx, expected.instantiate(tcx, key.args), |re, _dbi| {
-            match re.kind() {
-                ty::ReErased => infcx.next_nll_region_var(
-                    NllRegionVariableOrigin::Existential { name: None },
-                    || crate::RegionCtxt::Existential(None),
-                ),
-                _ => re,
-            }
-        });
+        let expected_ty =
+            ty::fold_regions(tcx, expected.ty.instantiate(tcx, key.args), |re, _dbi| {
+                match re.kind() {
+                    ty::ReErased => infcx.next_nll_region_var(
+                        NllRegionVariableOrigin::Existential { name: None },
+                        || crate::RegionCtxt::Existential(None),
+                    ),
+                    _ => re,
+                }
+            });
 
         // We now simply equate the expected with the actual hidden type.
         let locations = Locations::All(hidden_type.span);
@@ -555,13 +553,18 @@ pub(crate) fn apply_definition_site_hidden_types<'tcx>(
                     );
                     // We need to normalize both types in the old solver before equatingt them.
                     let actual_ty = ocx.normalize(&cause, infcx.param_env, hidden_type.ty);
-                    let expected_ty = ocx.normalize(&cause, infcx.param_env, expected.ty);
+                    let expected_ty = ocx.normalize(&cause, infcx.param_env, expected_ty);
                     ocx.eq(&cause, infcx.param_env, actual_ty, expected_ty).map_err(|_| NoSolution)
                 },
                 "equating opaque types",
             ),
         ) {
-            add_hidden_type(tcx, hidden_types, key.def_id, OpaqueHiddenType::new_error(tcx, guar));
+            add_hidden_type(
+                tcx,
+                hidden_types,
+                key.def_id,
+                DefinitionSiteHiddenType::new_error(tcx, guar),
+            );
         }
     }
     errors
@@ -676,24 +679,21 @@ impl<'tcx> InferCtxt<'tcx> {
     fn infer_opaque_definition_from_instantiation(
         &self,
         opaque_type_key: OpaqueTypeKey<'tcx>,
-        instantiated_ty: OpaqueHiddenType<'tcx>,
-    ) -> Result<Ty<'tcx>, NonDefiningUseReason<'tcx>> {
+        instantiated_ty: ProvisionalHiddenType<'tcx>,
+    ) -> Result<ty::DefinitionSiteHiddenType<'tcx>, NonDefiningUseReason<'tcx>> {
         opaque_type_has_defining_use_args(
             self,
             opaque_type_key,
             instantiated_ty.span,
             DefiningScopeKind::MirBorrowck,
         )?;
 
-        let definition_ty = instantiated_ty
-            .remap_generic_params_to_declaration_params(
-                opaque_type_key,
-                self.tcx,
-                DefiningScopeKind::MirBorrowck,
-            )
-            .ty;
-
-        definition_ty.error_reported()?;
+        let definition_ty = instantiated_ty.remap_generic_params_to_declaration_params(
+            opaque_type_key,
+            self.tcx,
+            DefiningScopeKind::MirBorrowck,
+        );
+        definition_ty.ty.skip_binder().error_reported()?;
         Ok(definition_ty)
     }
 }

compiler/rustc_borrowck/src/root_cx.rs

@@ -17,17 +17,16 @@ use crate::region_infer::opaque_types::{
 };
 use crate::type_check::{Locations, constraint_conversion};
 use crate::{
-    ClosureRegionRequirements, CollectRegionConstraintsResult, DefinitionSiteHiddenTypes,
-    PropagatedBorrowCheckResults, borrowck_check_region_constraints,
-    borrowck_collect_region_constraints,
+    ClosureRegionRequirements, CollectRegionConstraintsResult, PropagatedBorrowCheckResults,
+    borrowck_check_region_constraints, borrowck_collect_region_constraints,
 };
 
 /// The shared context used by both the root as well as all its nested
 /// items.
 pub(super) struct BorrowCheckRootCtxt<'tcx> {
     pub tcx: TyCtxt<'tcx>,
     root_def_id: LocalDefId,
-    hidden_types: DefinitionSiteHiddenTypes<'tcx>,
+    hidden_types: FxIndexMap<LocalDefId, ty::DefinitionSiteHiddenType<'tcx>>,
     /// The region constraints computed by [borrowck_collect_region_constraints]. This uses
     /// an [FxIndexMap] to guarantee that iterating over it visits nested bodies before
     /// their parents.
@@ -72,7 +71,10 @@ impl<'tcx> BorrowCheckRootCtxt<'tcx> {
         &self.propagated_borrowck_results[&nested_body_def_id].used_mut_upvars
     }
 
-    pub(super) fn finalize(self) -> Result<&'tcx DefinitionSiteHiddenTypes<'tcx>, ErrorGuaranteed> {
+    pub(super) fn finalize(
+        self,
+    ) -> Result<&'tcx FxIndexMap<LocalDefId, ty::DefinitionSiteHiddenType<'tcx>>, ErrorGuaranteed>
+    {
         if let Some(guar) = self.tainted_by_errors {
             Err(guar)
         } else {

compiler/rustc_hir_analysis/src/check/check.rs

@@ -430,7 +430,7 @@ fn best_definition_site_of_opaque<'tcx>(
                 .tcx
                 .mir_borrowck(item_def_id)
                 .ok()
-                .and_then(|opaque_types| opaque_types.0.get(&self.opaque_def_id))
+                .and_then(|opaque_types| opaque_types.get(&self.opaque_def_id))
             {
                 ControlFlow::Break((hidden_ty.span, item_def_id))
             } else {
@@ -493,7 +493,7 @@ fn best_definition_site_of_opaque<'tcx>(
 fn sanity_check_found_hidden_type<'tcx>(
     tcx: TyCtxt<'tcx>,
     key: ty::OpaqueTypeKey<'tcx>,
-    mut ty: ty::OpaqueHiddenType<'tcx>,
+    mut ty: ty::ProvisionalHiddenType<'tcx>,
 ) -> Result<(), ErrorGuaranteed> {
     if ty.ty.is_ty_var() {
         // Nothing was actually constrained.
@@ -529,7 +529,7 @@ fn sanity_check_found_hidden_type<'tcx>(
         Ok(())
     } else {
         let span = tcx.def_span(key.def_id);
-        let other = ty::OpaqueHiddenType { ty: hidden_ty, span };
+        let other = ty::ProvisionalHiddenType { ty: hidden_ty, span };
         Err(ty.build_mismatch_error(&other, tcx)?.emit())
     }
 }

compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -345,7 +345,7 @@ pub(super) fn type_of_opaque(
     def_id: DefId,
 ) -> Result<ty::EarlyBinder<'_, Ty<'_>>, CyclePlaceholder> {
     if let Some(def_id) = def_id.as_local() {
-        Ok(ty::EarlyBinder::bind(match tcx.hir_node_by_def_id(def_id).expect_opaque_ty().origin {
+        Ok(match tcx.hir_node_by_def_id(def_id).expect_opaque_ty().origin {
             hir::OpaqueTyOrigin::TyAlias { in_assoc_ty: false, .. } => {
                 opaque::find_opaque_ty_constraints_for_tait(
                     tcx,
@@ -378,7 +378,7 @@ pub(super) fn type_of_opaque(
                     DefiningScopeKind::MirBorrowck,
                 )
             }
-        }))
+        })
     } else {
         // Foreign opaque type will go through the foreign provider
         // and load the type from metadata.
@@ -390,7 +390,7 @@ pub(super) fn type_of_opaque_hir_typeck(
     tcx: TyCtxt<'_>,
     def_id: LocalDefId,
 ) -> ty::EarlyBinder<'_, Ty<'_>> {
-    ty::EarlyBinder::bind(match tcx.hir_node_by_def_id(def_id).expect_opaque_ty().origin {
+    match tcx.hir_node_by_def_id(def_id).expect_opaque_ty().origin {
         hir::OpaqueTyOrigin::TyAlias { in_assoc_ty: false, .. } => {
             opaque::find_opaque_ty_constraints_for_tait(tcx, def_id, DefiningScopeKind::HirTypeck)
         }
@@ -419,7 +419,7 @@ pub(super) fn type_of_opaque_hir_typeck(
                 DefiningScopeKind::HirTypeck,
             )
         }
-    })
+    }
 }
 
 fn infer_placeholder_type<'tcx>(