Remove some unnecessary cloning in method_resolution

8 files changed, 76 insertions, 78 deletions

diff --git a/Cargo.toml b/Cargo.toml
index e8e82914c7c..80b9ba8acb9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -105,6 +105,10 @@ anyhow = "1.0.75"
 arrayvec = "0.7.4"
 bitflags = "2.4.1"
 cargo_metadata = "0.18.1"
+chalk-solve = { version = "0.96.0", default-features = false }
+chalk-ir = "0.96.0"
+chalk-recursive = { version = "0.96.0", default-features = false }
+chalk-derive = "0.96.0"
 command-group = "2.0.1"
 crossbeam-channel = "0.5.8"
 dissimilar = "1.0.7"
diff --git a/crates/hir-ty/Cargo.toml b/crates/hir-ty/Cargo.toml
index 41e2f7ad73c..3cfedcdcb4d 100644
--- a/crates/hir-ty/Cargo.toml
+++ b/crates/hir-ty/Cargo.toml
@@ -23,10 +23,10 @@ oorandom = "11.1.3"
 tracing.workspace = true
 rustc-hash.workspace = true
 scoped-tls = "1.0.0"
-chalk-solve = { version = "0.96.0", default-features = false }
-chalk-ir = "0.96.0"
-chalk-recursive = { version = "0.96.0", default-features = false }
-chalk-derive = "0.96.0"
+chalk-solve.workspace = true
+chalk-ir.workspace = true
+chalk-recursive.workspace = true
+chalk-derive.workspace = true
 la-arena.workspace = true
 once_cell = "1.17.0"
 triomphe.workspace = true
diff --git a/crates/hir-ty/src/infer/coerce.rs b/crates/hir-ty/src/infer/coerce.rs
index 61638c43d9c..ff6de61ba64 100644
--- a/crates/hir-ty/src/infer/coerce.rs
+++ b/crates/hir-ty/src/infer/coerce.rs
@@ -647,7 +647,7 @@ impl InferenceTable<'_> {
         let goal: InEnvironment<DomainGoal> =
             InEnvironment::new(&self.trait_env.env, coerce_unsized_tref.cast(Interner));
 
-        let canonicalized = self.canonicalize(goal);
+        let canonicalized = self.canonicalize_with_free_vars(goal);
 
         // FIXME: rustc's coerce_unsized is more specialized -- it only tries to
         // solve `CoerceUnsized` and `Unsize` goals at this point and leaves the
diff --git a/crates/hir-ty/src/infer/expr.rs b/crates/hir-ty/src/infer/expr.rs
index 5c50f42d560..231eea041be 100644
--- a/crates/hir-ty/src/infer/expr.rs
+++ b/crates/hir-ty/src/infer/expr.rs
@@ -774,7 +774,7 @@ impl InferenceContext<'_> {
                     let receiver_adjustments = method_resolution::resolve_indexing_op(
                         self.db,
                         self.table.trait_env.clone(),
-                        canonicalized.value,
+                        canonicalized,
                         index_trait,
                     );
                     let (self_ty, mut adj) = receiver_adjustments
@@ -1559,7 +1559,7 @@ impl InferenceContext<'_> {
                 let canonicalized_receiver = self.canonicalize(receiver_ty.clone());
                 let resolved = method_resolution::lookup_method(
                     self.db,
-                    &canonicalized_receiver.value,
+                    &canonicalized_receiver,
                     self.table.trait_env.clone(),
                     self.get_traits_in_scope().as_ref().left_or_else(|&it| it),
                     VisibleFromModule::Filter(self.resolver.module()),
@@ -1608,7 +1608,7 @@ impl InferenceContext<'_> {
 
         let resolved = method_resolution::lookup_method(
             self.db,
-            &canonicalized_receiver.value,
+            &canonicalized_receiver,
             self.table.trait_env.clone(),
             self.get_traits_in_scope().as_ref().left_or_else(|&it| it),
             VisibleFromModule::Filter(self.resolver.module()),
@@ -1641,7 +1641,7 @@ impl InferenceContext<'_> {
                 };
 
                 let assoc_func_with_same_name = method_resolution::iterate_method_candidates(
-                    &canonicalized_receiver.value,
+                    &canonicalized_receiver,
                     self.db,
                     self.table.trait_env.clone(),
                     self.get_traits_in_scope().as_ref().left_or_else(|&it| it),
diff --git a/crates/hir-ty/src/infer/path.rs b/crates/hir-ty/src/infer/path.rs
index 16ae028427d..8f537bb448b 100644
--- a/crates/hir-ty/src/infer/path.rs
+++ b/crates/hir-ty/src/infer/path.rs
@@ -321,7 +321,7 @@ impl InferenceContext<'_> {
 
         let mut not_visible = None;
         let res = method_resolution::iterate_method_candidates(
-            &canonical_ty.value,
+            &canonical_ty,
             self.db,
             self.table.trait_env.clone(),
             self.get_traits_in_scope().as_ref().left_or_else(|&it| it),
diff --git a/crates/hir-ty/src/infer/unify.rs b/crates/hir-ty/src/infer/unify.rs
index 00c9246d43e..c3614e44527 100644
--- a/crates/hir-ty/src/infer/unify.rs
+++ b/crates/hir-ty/src/infer/unify.rs
@@ -23,12 +23,9 @@ use crate::{
 };
 
 impl InferenceContext<'_> {
-    pub(super) fn canonicalize<T: TypeFoldable<Interner> + HasInterner<Interner = Interner>>(
-        &mut self,
-        t: T,
-    ) -> Canonicalized<T>
+    pub(super) fn canonicalize<T>(&mut self, t: T) -> Canonical<T>
     where
-        T: HasInterner<Interner = Interner>,
+        T: TypeFoldable<Interner> + HasInterner<Interner = Interner>,
     {
         self.table.canonicalize(t)
     }
@@ -128,14 +125,14 @@ impl<T: HasInterner<Interner = Interner>> Canonicalized<T> {
             }),
         );
         for (i, v) in solution.value.iter(Interner).enumerate() {
-            let var = self.free_vars[i].clone();
+            let var = &self.free_vars[i];
             if let Some(ty) = v.ty(Interner) {
                 // eagerly replace projections in the type; we may be getting types
                 // e.g. from where clauses where this hasn't happened yet
                 let ty = ctx.normalize_associated_types_in(new_vars.apply(ty.clone(), Interner));
                 ctx.unify(var.assert_ty_ref(Interner), &ty);
             } else {
-                let _ = ctx.try_unify(&var, &new_vars.apply(v.clone(), Interner));
+                let _ = ctx.try_unify(var, &new_vars.apply(v.clone(), Interner));
             }
         }
     }
@@ -307,12 +304,9 @@ impl<'a> InferenceTable<'a> {
         .intern(Interner)
     }
 
-    pub(crate) fn canonicalize<T: TypeFoldable<Interner> + HasInterner<Interner = Interner>>(
-        &mut self,
-        t: T,
-    ) -> Canonicalized<T>
+    pub(crate) fn canonicalize_with_free_vars<T>(&mut self, t: T) -> Canonicalized<T>
     where
-        T: HasInterner<Interner = Interner>,
+        T: TypeFoldable<Interner> + HasInterner<Interner = Interner>,
     {
         // try to resolve obligations before canonicalizing, since this might
         // result in new knowledge about variables
@@ -326,6 +320,16 @@ impl<'a> InferenceTable<'a> {
         Canonicalized { value: result.quantified, free_vars }
     }
 
+    pub(crate) fn canonicalize<T>(&mut self, t: T) -> Canonical<T>
+    where
+        T: TypeFoldable<Interner> + HasInterner<Interner = Interner>,
+    {
+        // try to resolve obligations before canonicalizing, since this might
+        // result in new knowledge about variables
+        self.resolve_obligations_as_possible();
+        self.var_unification_table.canonicalize(Interner, t).quantified
+    }
+
     /// Recurses through the given type, normalizing associated types mentioned
     /// in it by replacing them by type variables and registering obligations to
     /// resolve later. This should be done once for every type we get from some
@@ -541,7 +545,7 @@ impl<'a> InferenceTable<'a> {
             Err(_) => return false,
         };
         result.goals.iter().all(|goal| {
-            let canonicalized = self.canonicalize(goal.clone());
+            let canonicalized = self.canonicalize_with_free_vars(goal.clone());
             self.try_resolve_obligation(&canonicalized).is_some()
         })
     }
@@ -602,7 +606,7 @@ impl<'a> InferenceTable<'a> {
         let in_env = InEnvironment::new(&self.trait_env.env, goal);
         let canonicalized = self.canonicalize(in_env);
 
-        self.db.trait_solve(self.trait_env.krate, self.trait_env.block, canonicalized.value)
+        self.db.trait_solve(self.trait_env.krate, self.trait_env.block, canonicalized)
     }
 
     pub(crate) fn register_obligation(&mut self, goal: Goal) {
@@ -611,7 +615,7 @@ impl<'a> InferenceTable<'a> {
     }
 
     fn register_obligation_in_env(&mut self, goal: InEnvironment<Goal>) {
-        let canonicalized = self.canonicalize(goal);
+        let canonicalized = self.canonicalize_with_free_vars(goal);
         let solution = self.try_resolve_obligation(&canonicalized);
         if matches!(solution, Some(Solution::Ambig(_))) {
             self.pending_obligations.push(canonicalized);
@@ -824,11 +828,7 @@ impl<'a> InferenceTable<'a> {
             environment: trait_env.clone(),
         };
         let canonical = self.canonicalize(obligation.clone());
-        if self
-            .db
-            .trait_solve(krate, self.trait_env.block, canonical.value.cast(Interner))
-            .is_some()
-        {
+        if self.db.trait_solve(krate, self.trait_env.block, canonical.cast(Interner)).is_some() {
             self.register_obligation(obligation.goal);
             let return_ty = self.normalize_projection_ty(projection);
             for fn_x in [FnTrait::Fn, FnTrait::FnMut, FnTrait::FnOnce] {
@@ -841,7 +841,7 @@ impl<'a> InferenceTable<'a> {
                 let canonical = self.canonicalize(obligation.clone());
                 if self
                     .db
-                    .trait_solve(krate, self.trait_env.block, canonical.value.cast(Interner))
+                    .trait_solve(krate, self.trait_env.block, canonical.cast(Interner))
                     .is_some()
                 {
                     return Some((fn_x, arg_tys, return_ty));
diff --git a/crates/hir-ty/src/method_resolution.rs b/crates/hir-ty/src/method_resolution.rs
index bb2c436a99a..d63accc2a4b 100644
--- a/crates/hir-ty/src/method_resolution.rs
+++ b/crates/hir-ty/src/method_resolution.rs
@@ -973,7 +973,7 @@ pub fn iterate_method_candidates_dyn(
             deref_chain.into_iter().try_for_each(|(receiver_ty, adj)| {
                 iterate_method_candidates_with_autoref(
                     &mut table,
-                    &receiver_ty,
+                    receiver_ty,
                     adj,
                     traits_in_scope,
                     visible_from_module,
@@ -1000,7 +1000,7 @@ pub fn iterate_method_candidates_dyn(
 #[tracing::instrument(skip_all, fields(name = ?name))]
 fn iterate_method_candidates_with_autoref(
     table: &mut InferenceTable<'_>,
-    receiver_ty: &Canonical<Ty>,
+    receiver_ty: Canonical<Ty>,
     first_adjustment: ReceiverAdjustments,
     traits_in_scope: &FxHashSet<TraitId>,
     visible_from_module: VisibleFromModule,
@@ -1031,7 +1031,7 @@ fn iterate_method_candidates_with_autoref(
         maybe_reborrowed.autoderefs += 1;
     }
 
-    iterate_method_candidates_by_receiver(receiver_ty, maybe_reborrowed)?;
+    iterate_method_candidates_by_receiver(receiver_ty.clone(), maybe_reborrowed)?;
 
     let refed = Canonical {
         value: TyKind::Ref(Mutability::Not, static_lifetime(), receiver_ty.value.clone())
@@ -1039,7 +1039,7 @@ fn iterate_method_candidates_with_autoref(
         binders: receiver_ty.binders.clone(),
     };
 
-    iterate_method_candidates_by_receiver(&refed, first_adjustment.with_autoref(Mutability::Not))?;
+    iterate_method_candidates_by_receiver(refed, first_adjustment.with_autoref(Mutability::Not))?;
 
     let ref_muted = Canonical {
         value: TyKind::Ref(Mutability::Mut, static_lifetime(), receiver_ty.value.clone())
@@ -1047,16 +1047,13 @@ fn iterate_method_candidates_with_autoref(
         binders: receiver_ty.binders.clone(),
     };
 
-    iterate_method_candidates_by_receiver(
-        &ref_muted,
-        first_adjustment.with_autoref(Mutability::Mut),
-    )
+    iterate_method_candidates_by_receiver(ref_muted, first_adjustment.with_autoref(Mutability::Mut))
 }
 
 #[tracing::instrument(skip_all, fields(name = ?name))]
 fn iterate_method_candidates_by_receiver(
     table: &mut InferenceTable<'_>,
-    receiver_ty: &Canonical<Ty>,
+    receiver_ty: Canonical<Ty>,
     receiver_adjustments: ReceiverAdjustments,
     traits_in_scope: &FxHashSet<TraitId>,
     visible_from_module: VisibleFromModule,
@@ -1143,9 +1140,9 @@ fn iterate_trait_method_candidates(
     callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
 ) -> ControlFlow<()> {
     let db = table.db;
-    let env = table.trait_env.clone();
 
-    let canonical_self_ty = table.canonicalize(self_ty.clone()).value;
+    let canonical_self_ty = table.canonicalize(self_ty.clone());
+    let TraitEnvironment { krate, block, .. } = *table.trait_env;
 
     'traits: for &t in traits_in_scope {
         let data = db.trait_data(t);
@@ -1160,7 +1157,7 @@ fn iterate_trait_method_candidates(
         {
             // FIXME: this should really be using the edition of the method name's span, in case it
             // comes from a macro
-            if db.crate_graph()[env.krate].edition < Edition::Edition2021 {
+            if db.crate_graph()[krate].edition < Edition::Edition2021 {
                 continue;
             }
         }
@@ -1179,8 +1176,8 @@ fn iterate_trait_method_candidates(
                     IsValidCandidate::No => continue,
                 };
             if !known_implemented {
-                let goal = generic_implements_goal(db, env.clone(), t, &canonical_self_ty);
-                if db.trait_solve(env.krate, env.block, goal.cast(Interner)).is_none() {
+                let goal = generic_implements_goal(db, &table.trait_env, t, &canonical_self_ty);
+                if db.trait_solve(krate, block, goal.cast(Interner)).is_none() {
                     continue 'traits;
                 }
             }
@@ -1361,7 +1358,7 @@ pub(crate) fn resolve_indexing_op(
     let ty = table.instantiate_canonical(ty);
     let deref_chain = autoderef_method_receiver(&mut table, ty);
     for (ty, adj) in deref_chain {
-        let goal = generic_implements_goal(db, table.trait_env.clone(), index_trait, &ty);
+        let goal = generic_implements_goal(db, &table.trait_env, index_trait, &ty);
         if db
             .trait_solve(table.trait_env.krate, table.trait_env.block, goal.cast(Interner))
             .is_some()
@@ -1544,7 +1541,7 @@ fn is_valid_impl_fn_candidate(
 
         for goal in goals.clone() {
             let in_env = InEnvironment::new(&table.trait_env.env, goal);
-            let canonicalized = table.canonicalize(in_env);
+            let canonicalized = table.canonicalize_with_free_vars(in_env);
             let solution = table.db.trait_solve(
                 table.trait_env.krate,
                 table.trait_env.block,
@@ -1582,10 +1579,10 @@ fn is_valid_impl_fn_candidate(
 pub fn implements_trait(
     ty: &Canonical<Ty>,
     db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: &TraitEnvironment,
     trait_: TraitId,
 ) -> bool {
-    let goal = generic_implements_goal(db, env.clone(), trait_, ty);
+    let goal = generic_implements_goal(db, env, trait_, ty);
     let solution = db.trait_solve(env.krate, env.block, goal.cast(Interner));
 
     solution.is_some()
@@ -1594,10 +1591,10 @@ pub fn implements_trait(
 pub fn implements_trait_unique(
     ty: &Canonical<Ty>,
     db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: &TraitEnvironment,
     trait_: TraitId,
 ) -> bool {
-    let goal = generic_implements_goal(db, env.clone(), trait_, ty);
+    let goal = generic_implements_goal(db, env, trait_, ty);
     let solution = db.trait_solve(env.krate, env.block, goal.cast(Interner));
 
     matches!(solution, Some(crate::Solution::Unique(_)))
@@ -1608,32 +1605,34 @@ pub fn implements_trait_unique(
 #[tracing::instrument(skip_all)]
 fn generic_implements_goal(
     db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: &TraitEnvironment,
     trait_: TraitId,
     self_ty: &Canonical<Ty>,
 ) -> Canonical<InEnvironment<super::DomainGoal>> {
-    let mut kinds = self_ty.binders.interned().to_vec();
+    let binders = self_ty.binders.interned();
     let trait_ref = TyBuilder::trait_ref(db, trait_)
         .push(self_ty.value.clone())
-        .fill_with_bound_vars(DebruijnIndex::INNERMOST, kinds.len())
+        .fill_with_bound_vars(DebruijnIndex::INNERMOST, binders.len())
         .build();
-    kinds.extend(trait_ref.substitution.iter(Interner).skip(1).map(|it| {
-        let vk = match it.data(Interner) {
-            chalk_ir::GenericArgData::Ty(_) => {
-                chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General)
-            }
-            chalk_ir::GenericArgData::Lifetime(_) => chalk_ir::VariableKind::Lifetime,
-            chalk_ir::GenericArgData::Const(c) => {
-                chalk_ir::VariableKind::Const(c.data(Interner).ty.clone())
-            }
-        };
-        chalk_ir::WithKind::new(vk, UniverseIndex::ROOT)
-    }));
+
+    let kinds =
+        binders.iter().cloned().chain(trait_ref.substitution.iter(Interner).skip(1).map(|it| {
+            let vk = match it.data(Interner) {
+                chalk_ir::GenericArgData::Ty(_) => {
+                    chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General)
+                }
+                chalk_ir::GenericArgData::Lifetime(_) => chalk_ir::VariableKind::Lifetime,
+                chalk_ir::GenericArgData::Const(c) => {
+                    chalk_ir::VariableKind::Const(c.data(Interner).ty.clone())
+                }
+            };
+            chalk_ir::WithKind::new(vk, UniverseIndex::ROOT)
+        }));
+    let binders = CanonicalVarKinds::from_iter(Interner, kinds);
+
     let obligation = trait_ref.cast(Interner);
-    Canonical {
-        binders: CanonicalVarKinds::from_iter(Interner, kinds),
-        value: InEnvironment::new(&env.env, obligation),
-    }
+    let value = InEnvironment::new(&env.env, obligation);
+    Canonical { binders, value }
 }
 
 fn autoderef_method_receiver(
@@ -1644,7 +1643,7 @@ fn autoderef_method_receiver(
     let mut autoderef = autoderef::Autoderef::new(table, ty, false);
     while let Some((ty, derefs)) = autoderef.next() {
         deref_chain.push((
-            autoderef.table.canonicalize(ty).value,
+            autoderef.table.canonicalize(ty),
             ReceiverAdjustments { autoref: None, autoderefs: derefs, unsize_array: false },
         ));
     }
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index 4872c47c31d..307765558db 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -4025,7 +4025,7 @@ impl Type {
 
         let canonical_ty =
             Canonical { value: self.ty.clone(), binders: CanonicalVarKinds::empty(Interner) };
-        method_resolution::implements_trait(&canonical_ty, db, self.env.clone(), trait_)
+        method_resolution::implements_trait(&canonical_ty, db, &self.env, trait_)
     }
 
     /// Checks that particular type `ty` implements `std::ops::FnOnce`.
@@ -4040,12 +4040,7 @@ impl Type {
 
         let canonical_ty =
             Canonical { value: self.ty.clone(), binders: CanonicalVarKinds::empty(Interner) };
-        method_resolution::implements_trait_unique(
-            &canonical_ty,
-            db,
-            self.env.clone(),
-            fnonce_trait,
-        )
+        method_resolution::implements_trait_unique(&canonical_ty, db, &self.env, fnonce_trait)
     }
 
     // FIXME: Find better API that also handles const generics