3 files changed, 90 insertions, 41 deletions

diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index 3af05394c..d6a17e469 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -569,12 +569,19 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     ) -> Ty {
         let receiver_ty = self.infer_expr(receiver, &Expectation::none());
         let canonicalized_receiver = self.canonicalizer().canonicalize_ty(receiver_ty.clone());
-        let resolved = method_resolution::lookup_method(
-            &canonicalized_receiver.value,
-            self.db,
-            method_name,
-            &self.resolver,
-        );
+
+        let traits_in_scope = self.resolver.traits_in_scope(self.db);
+
+        let resolved = self.resolver.krate().and_then(|krate| {
+            method_resolution::lookup_method(
+                &canonicalized_receiver.value,
+                self.db,
+                self.trait_env.clone(),
+                krate,
+                &traits_in_scope,
+                method_name,
+            )
+        });
         let (derefed_receiver_ty, method_ty, def_generics) = match resolved {
             Some((ty, func)) => {
                 let ty = canonicalized_receiver.decanonicalize_ty(ty);
diff --git a/crates/ra_hir_ty/src/infer/path.rs b/crates/ra_hir_ty/src/infer/path.rs
index ffd358367..2c1d4831d 100644
--- a/crates/ra_hir_ty/src/infer/path.rs
+++ b/crates/ra_hir_ty/src/infer/path.rs
@@ -11,7 +11,7 @@ use hir_expand::name::Name;
 
 use crate::{db::HirDatabase, method_resolution, Substs, Ty, TypeWalk, ValueTyDefId};
 
-use super::{ExprOrPatId, InferenceContext, TraitRef};
+use super::{ExprOrPatId, InferenceContext, TraitEnvironment, TraitRef};
 
 impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     pub(super) fn infer_path(
@@ -193,11 +193,16 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         }
 
         let canonical_ty = self.canonicalizer().canonicalize_ty(ty.clone());
+        let env = TraitEnvironment::lower(self.db, &self.resolver);
+        let krate = self.resolver.krate()?;
+        let traits_in_scope = self.resolver.traits_in_scope(self.db);
 
         method_resolution::iterate_method_candidates(
             &canonical_ty.value,
             self.db,
-            &self.resolver.clone(),
+            env,
+            krate,
+            &traits_in_scope,
             Some(name),
             method_resolution::LookupMode::Path,
             move |_ty, item| {
diff --git a/crates/ra_hir_ty/src/method_resolution.rs b/crates/ra_hir_ty/src/method_resolution.rs
index 55435e6ea..5bacbbd7c 100644
--- a/crates/ra_hir_ty/src/method_resolution.rs
+++ b/crates/ra_hir_ty/src/method_resolution.rs
@@ -6,13 +6,13 @@ use std::sync::Arc;
 
 use arrayvec::ArrayVec;
 use hir_def::{
-    lang_item::LangItemTarget, resolver::Resolver, type_ref::Mutability, AssocContainerId,
-    AssocItemId, FunctionId, HasModule, ImplId, Lookup, TraitId,
+    lang_item::LangItemTarget, type_ref::Mutability, AssocContainerId, AssocItemId, FunctionId,
+    HasModule, ImplId, Lookup, TraitId,
 };
 use hir_expand::name::Name;
 use ra_db::CrateId;
 use ra_prof::profile;
-use rustc_hash::FxHashMap;
+use rustc_hash::{FxHashMap, FxHashSet};
 
 use super::Substs;
 use crate::{
@@ -144,14 +144,24 @@ impl Ty {
 pub(crate) fn lookup_method(
     ty: &Canonical<Ty>,
     db: &impl HirDatabase,
+    env: Arc<TraitEnvironment>,
+    krate: CrateId,
+    traits_in_scope: &FxHashSet<TraitId>,
     name: &Name,
-    resolver: &Resolver,
 ) -> Option<(Ty, FunctionId)> {
-    iterate_method_candidates(ty, db, resolver, Some(name), LookupMode::MethodCall, |ty, f| match f
-    {
-        AssocItemId::FunctionId(f) => Some((ty.clone(), f)),
-        _ => None,
-    })
+    iterate_method_candidates(
+        ty,
+        db,
+        env,
+        krate,
+        &traits_in_scope,
+        Some(name),
+        LookupMode::MethodCall,
+        |ty, f| match f {
+            AssocItemId::FunctionId(f) => Some((ty.clone(), f)),
+            _ => None,
+        },
+    )
 }
 
 /// Whether we're looking up a dotted method call (like `v.len()`) or a path
@@ -172,7 +182,9 @@ pub enum LookupMode {
 pub fn iterate_method_candidates<T>(
     ty: &Canonical<Ty>,
     db: &impl HirDatabase,
-    resolver: &Resolver,
+    env: Arc<TraitEnvironment>,
+    krate: CrateId,
+    traits_in_scope: &FxHashSet<TraitId>,
     name: Option<&Name>,
     mode: LookupMode,
     mut callback: impl FnMut(&Ty, AssocItemId) -> Option<T>,
@@ -187,9 +199,7 @@ pub fn iterate_method_candidates<T>(
             // Also note that when we've got a receiver like &S, even if the method we
             // find in the end takes &self, we still do the autoderef step (just as
             // rustc does an autoderef and then autoref again).
-            let environment = TraitEnvironment::lower(db, resolver);
-            let ty = InEnvironment { value: ty.clone(), environment };
-            let krate = resolver.krate()?;
+            let ty = InEnvironment { value: ty.clone(), environment: env.clone() };
 
             // We have to be careful about the order we're looking at candidates
             // in here. Consider the case where we're resolving `x.clone()`
@@ -209,7 +219,9 @@ pub fn iterate_method_candidates<T>(
                 if let Some(result) = iterate_method_candidates_with_autoref(
                     &deref_chain[i..],
                     db,
-                    resolver,
+                    env.clone(),
+                    krate,
+                    traits_in_scope,
                     name,
                     &mut callback,
                 ) {
@@ -220,7 +232,15 @@ pub fn iterate_method_candidates<T>(
         }
         LookupMode::Path => {
             // No autoderef for path lookups
-            iterate_method_candidates_for_self_ty(&ty, db, resolver, name, &mut callback)
+            iterate_method_candidates_for_self_ty(
+                &ty,
+                db,
+                env,
+                krate,
+                traits_in_scope,
+                name,
+                &mut callback,
+            )
         }
     }
 }
@@ -228,7 +248,9 @@ pub fn iterate_method_candidates<T>(
 fn iterate_method_candidates_with_autoref<T>(
     deref_chain: &[Canonical<Ty>],
     db: &impl HirDatabase,
-    resolver: &Resolver,
+    env: Arc<TraitEnvironment>,
+    krate: CrateId,
+    traits_in_scope: &FxHashSet<TraitId>,
     name: Option<&Name>,
     mut callback: impl FnMut(&Ty, AssocItemId) -> Option<T>,
 ) -> Option<T> {
@@ -236,7 +258,9 @@ fn iterate_method_candidates_with_autoref<T>(
         &deref_chain[0],
         &deref_chain[1..],
         db,
-        resolver,
+        env.clone(),
+        krate,
+        &traits_in_scope,
         name,
         &mut callback,
     ) {
@@ -250,7 +274,9 @@ fn iterate_method_candidates_with_autoref<T>(
         &refed,
         deref_chain,
         db,
-        resolver,
+        env.clone(),
+        krate,
+        &traits_in_scope,
         name,
         &mut callback,
     ) {
@@ -264,7 +290,9 @@ fn iterate_method_candidates_with_autoref<T>(
         &ref_muted,
         deref_chain,
         db,
-        resolver,
+        env.clone(),
+        krate,
+        &traits_in_scope,
         name,
         &mut callback,
     ) {
@@ -277,14 +305,15 @@ fn iterate_method_candidates_by_receiver<T>(
     receiver_ty: &Canonical<Ty>,
     rest_of_deref_chain: &[Canonical<Ty>],
     db: &impl HirDatabase,
-    resolver: &Resolver,
+    env: Arc<TraitEnvironment>,
+    krate: CrateId,
+    traits_in_scope: &FxHashSet<TraitId>,
     name: Option<&Name>,
     mut callback: impl FnMut(&Ty, AssocItemId) -> Option<T>,
 ) -> Option<T> {
     // We're looking for methods with *receiver* type receiver_ty. These could
     // be found in any of the derefs of receiver_ty, so we have to go through
     // that.
-    let krate = resolver.krate()?;
     for self_ty in std::iter::once(receiver_ty).chain(rest_of_deref_chain) {
         if let Some(result) =
             iterate_inherent_methods(self_ty, db, name, Some(receiver_ty), krate, &mut callback)
@@ -296,7 +325,9 @@ fn iterate_method_candidates_by_receiver<T>(
         if let Some(result) = iterate_trait_method_candidates(
             self_ty,
             db,
-            resolver,
+            env.clone(),
+            krate,
+            &traits_in_scope,
             name,
             Some(receiver_ty),
             &mut callback,
@@ -310,17 +341,25 @@ fn iterate_method_candidates_by_receiver<T>(
 fn iterate_method_candidates_for_self_ty<T>(
     self_ty: &Canonical<Ty>,
     db: &impl HirDatabase,
-    resolver: &Resolver,
+    env: Arc<TraitEnvironment>,
+    krate: CrateId,
+    traits_in_scope: &FxHashSet<TraitId>,
     name: Option<&Name>,
     mut callback: impl FnMut(&Ty, AssocItemId) -> Option<T>,
 ) -> Option<T> {
-    let krate = resolver.krate()?;
     if let Some(result) = iterate_inherent_methods(self_ty, db, name, None, krate, &mut callback) {
         return Some(result);
     }
-    if let Some(result) =
-        iterate_trait_method_candidates(self_ty, db, resolver, name, None, &mut callback)
-    {
+    if let Some(result) = iterate_trait_method_candidates(
+        self_ty,
+        db,
+        env,
+        krate,
+        traits_in_scope,
+        name,
+        None,
+        &mut callback,
+    ) {
         return Some(result);
     }
     None
@@ -329,14 +368,13 @@ fn iterate_method_candidates_for_self_ty<T>(
 fn iterate_trait_method_candidates<T>(
     self_ty: &Canonical<Ty>,
     db: &impl HirDatabase,
-    resolver: &Resolver,
+    env: Arc<TraitEnvironment>,
+    krate: CrateId,
+    traits_in_scope: &FxHashSet<TraitId>,
     name: Option<&Name>,
     receiver_ty: Option<&Canonical<Ty>>,
     mut callback: impl FnMut(&Ty, AssocItemId) -> Option<T>,
 ) -> Option<T> {
-    let krate = resolver.krate()?;
-    // FIXME: maybe put the trait_env behind a query (need to figure out good input parameters for that)
-    let env = TraitEnvironment::lower(db, resolver);
     // if ty is `impl Trait` or `dyn Trait`, the trait doesn't need to be in scope
     let inherent_trait = self_ty.value.inherent_trait().into_iter();
     // if we have `T: Trait` in the param env, the trait doesn't need to be in scope
@@ -344,8 +382,7 @@ fn iterate_trait_method_candidates<T>(
         .trait_predicates_for_self_ty(&self_ty.value)
         .map(|tr| tr.trait_)
         .flat_map(|t| all_super_traits(db, t));
-    let traits =
-        inherent_trait.chain(traits_from_env).chain(resolver.traits_in_scope(db).into_iter());
+    let traits = inherent_trait.chain(traits_from_env).chain(traits_in_scope.iter().copied());
     'traits: for t in traits {
         let data = db.trait_data(t);