remove non-borrowck member constraints

rust-lang · bors · Dec 21, 2024 · Dec 19, 2024 · Dec 19, 2024 · Dec 20, 2024
commit 9792cf0d6b865727c0978fb8adef7b1254f2d5e5
diff --git a/compiler/rustc_borrowck/src/member_constraints.rs b/compiler/rustc_borrowck/src/member_constraints.rs
@@ -22,7 +22,7 @@ where
     /// Stores the data about each `R0 member of [R1..Rn]` constraint.
     /// These are organized into a linked list, so each constraint
     /// contains the index of the next constraint with the same `R0`.
-    constraints: IndexVec<NllMemberConstraintIndex, NllMemberConstraint<'tcx>>,
+    constraints: IndexVec<NllMemberConstraintIndex, MemberConstraint<'tcx>>,
 
     /// Stores the `R1..Rn` regions for *all* sets. For any given
     /// constraint, we keep two indices so that we can pull out a
@@ -32,7 +32,7 @@ where
 
 /// Represents a `R0 member of [R1..Rn]` constraint
 #[derive(Debug)]
-pub(crate) struct NllMemberConstraint<'tcx> {
+pub(crate) struct MemberConstraint<'tcx> {
     next_constraint: Option<NllMemberConstraintIndex>,
 
     /// The span where the hidden type was instantiated.
@@ -87,7 +87,7 @@ impl<'tcx> MemberConstraintSet<'tcx, ty::RegionVid> {
         let start_index = self.choice_regions.len();
         self.choice_regions.extend(choice_regions);
         let end_index = self.choice_regions.len();
-        let constraint_index = self.constraints.push(NllMemberConstraint {
+        let constraint_index = self.constraints.push(MemberConstraint {
             next_constraint,
             member_region_vid,
             definition_span,
@@ -98,14 +98,6 @@ impl<'tcx> MemberConstraintSet<'tcx, ty::RegionVid> {
         });
         self.first_constraints.insert(member_region_vid, constraint_index);
     }
-
-    // TODO: removed in the next commit
-    pub(crate) fn push_constraint(
-        &mut self,
-        _: &rustc_middle::infer::MemberConstraint<'tcx>,
-        _: impl FnMut(ty::Region<'tcx>) -> ty::RegionVid,
-    ) {
-    }
 }
 
 impl<'tcx, R1> MemberConstraintSet<'tcx, R1>
@@ -186,7 +178,7 @@ where
     /// R0 member of [R1..Rn]
     /// ```
     pub(crate) fn choice_regions(&self, pci: NllMemberConstraintIndex) -> &[ty::RegionVid] {
-        let NllMemberConstraint { start_index, end_index, .. } = &self.constraints[pci];
+        let MemberConstraint { start_index, end_index, .. } = &self.constraints[pci];
         &self.choice_regions[*start_index..*end_index]
     }
 }
@@ -195,9 +187,9 @@ impl<'tcx, R> Index<NllMemberConstraintIndex> for MemberConstraintSet<'tcx, R>
 where
     R: Copy + Eq,
 {
-    type Output = NllMemberConstraint<'tcx>;
+    type Output = MemberConstraint<'tcx>;
 
-    fn index(&self, i: NllMemberConstraintIndex) -> &NllMemberConstraint<'tcx> {
+    fn index(&self, i: NllMemberConstraintIndex) -> &MemberConstraint<'tcx> {
         &self.constraints[i]
     }
 }
@@ -219,7 +211,7 @@ where
 /// target_list: A -> B -> C -> D -> E -> F -> (None)
 /// ```
 fn append_list(
-    constraints: &mut IndexSlice<NllMemberConstraintIndex, NllMemberConstraint<'_>>,
+    constraints: &mut IndexSlice<NllMemberConstraintIndex, MemberConstraint<'_>>,
     target_list: NllMemberConstraintIndex,
     source_list: NllMemberConstraintIndex,
 ) {

diff --git a/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs b/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
@@ -77,17 +77,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
 
     #[instrument(skip(self), level = "debug")]
     pub(super) fn convert_all(&mut self, query_constraints: &QueryRegionConstraints<'tcx>) {
-        let QueryRegionConstraints { outlives, member_constraints } = query_constraints;
-
-        // Annoying: to invoke `self.to_region_vid`, we need access to
-        // `self.constraints`, but we also want to be mutating
-        // `self.member_constraints`. For now, just swap out the value
-        // we want and replace at the end.
-        let mut tmp = std::mem::take(&mut self.constraints.member_constraints);
-        for member_constraint in member_constraints {
-            tmp.push_constraint(member_constraint, |r| self.to_region_vid(r));
-        }
-        self.constraints.member_constraints = tmp;
+        let QueryRegionConstraints { outlives } = query_constraints;
 
         for &(predicate, constraint_category) in outlives {
             self.convert(predicate, constraint_category);
@@ -295,13 +285,8 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
 
         match result {
             Ok(TypeOpOutput { output: ty, constraints, .. }) => {
-                if let Some(constraints) = constraints {
-                    assert!(
-                        constraints.member_constraints.is_empty(),
-                        "no member constraints expected from normalizing: {:#?}",
-                        constraints.member_constraints
-                    );
-                    next_outlives_predicates.extend(constraints.outlives.iter().copied());
+                if let Some(QueryRegionConstraints { outlives }) = constraints {
+                    next_outlives_predicates.extend(outlives.iter().copied());
                 }
                 ty
             }

diff --git a/compiler/rustc_borrowck/src/universal_regions.rs b/compiler/rustc_borrowck/src/universal_regions.rs
@@ -880,6 +880,10 @@ impl<'tcx> UniversalRegionIndices<'tcx> {
     /// reference those regions from the `ParamEnv`. It is also used
     /// during initialization. Relies on the `indices` map having been
     /// fully initialized.
+    ///
+    /// Panics if `r` is not a registered universal region, most notably
+    /// if it is a placeholder. Handling placeholders requires access to the
+    /// `MirTypeckRegionConstraints`.
     fn to_region_vid(&self, r: ty::Region<'tcx>) -> RegionVid {
         if let ty::ReVar(..) = *r {
             r.as_var()

diff --git a/compiler/rustc_infer/src/infer/canonical/query_response.rs b/compiler/rustc_infer/src/infer/canonical/query_response.rs
@@ -316,16 +316,6 @@ impl<'tcx> InferCtxt<'tcx> {
             }),
         );
 
-        // ...also include the query member constraints.
-        output_query_region_constraints.member_constraints.extend(
-            query_response
-                .value
-                .region_constraints
-                .member_constraints
-                .iter()
-                .map(|p_c| instantiate_value(self.tcx, &result_args, p_c.clone())),
-        );
-
         let user_result: R =
             query_response.instantiate_projected(self.tcx, &result_args, |q_r| q_r.value.clone());
 
@@ -643,7 +633,7 @@ pub fn make_query_region_constraints<'tcx>(
     outlives_obligations: impl Iterator<Item = (Ty<'tcx>, ty::Region<'tcx>, ConstraintCategory<'tcx>)>,
     region_constraints: &RegionConstraintData<'tcx>,
 ) -> QueryRegionConstraints<'tcx> {
-    let RegionConstraintData { constraints, verifys, member_constraints } = region_constraints;
+    let RegionConstraintData { constraints, verifys } = region_constraints;
 
     assert!(verifys.is_empty());
 
@@ -674,5 +664,5 @@ pub fn make_query_region_constraints<'tcx>(
         }))
         .collect();
 
-    QueryRegionConstraints { outlives, member_constraints: member_constraints.clone() }
+    QueryRegionConstraints { outlives }
 }
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
@@ -17,7 +17,6 @@ pub use relate::StructurallyRelateAliases;
 pub use relate::combine::PredicateEmittingRelation;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
-use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::undo_log::{Rollback, UndoLogs};
 use rustc_data_structures::unify as ut;
 use rustc_errors::{DiagCtxtHandle, ErrorGuaranteed};
@@ -685,26 +684,6 @@ impl<'tcx> InferCtxt<'tcx> {
         self.inner.borrow_mut().unwrap_region_constraints().make_subregion(origin, a, b);
     }
 
-    /// Require that the region `r` be equal to one of the regions in
-    /// the set `regions`.
-    #[instrument(skip(self), level = "debug")]
-    pub fn add_member_constraint(
-        &self,
-        key: ty::OpaqueTypeKey<'tcx>,
-        definition_span: Span,
-        hidden_ty: Ty<'tcx>,
-        region: ty::Region<'tcx>,
-        in_regions: Lrc<Vec<ty::Region<'tcx>>>,
-    ) {
-        self.inner.borrow_mut().unwrap_region_constraints().add_member_constraint(
-            key,
-            definition_span,
-            hidden_ty,
-            region,
-            in_regions,
-        );
-    }
-
     /// Processes a `Coerce` predicate from the fulfillment context.
     /// This is NOT the preferred way to handle coercion, which is to
     /// invoke `FnCtxt::coerce` or a similar method (see `coercion.rs`).