7 files changed, 192 insertions, 112 deletions

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 346118350..3b479356f 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -21,8 +21,8 @@ use hir_expand::{
     MacroDefId,
 };
 use hir_ty::{
-    autoderef, display::HirFormatter, expr::ExprValidator, method_resolution::implements_trait,
-    ApplicationTy, Canonical, InEnvironment, TraitEnvironment, Ty, TyDefId, TypeCtor, TypeWalk,
+    autoderef, display::HirFormatter, expr::ExprValidator, method_resolution, ApplicationTy,
+    Canonical, InEnvironment, TraitEnvironment, Ty, TyDefId, TypeCtor, TypeWalk,
 };
 use ra_db::{CrateId, Edition, FileId};
 use ra_prof::profile;
@@ -120,7 +120,8 @@ impl_froms!(
     BuiltinType
 );
 
-pub use hir_def::{attr::Attrs, visibility::Visibility};
+pub use hir_def::{attr::Attrs, visibility::Visibility, AssocItemId};
+use rustc_hash::FxHashSet;
 
 impl Module {
     pub(crate) fn new(krate: Crate, crate_module_id: LocalModuleId) -> Module {
@@ -891,7 +892,13 @@ impl Type {
         };
 
         let canonical_ty = Canonical { value: self.ty.value.clone(), num_vars: 0 };
-        implements_trait(&canonical_ty, db, self.ty.environment.clone(), krate, std_future_trait)
+        method_resolution::implements_trait(
+            &canonical_ty,
+            db,
+            self.ty.environment.clone(),
+            krate,
+            std_future_trait,
+        )
     }
 
     // FIXME: this method is broken, as it doesn't take closures into account.
@@ -1002,6 +1009,65 @@ impl Type {
         None
     }
 
+    pub fn iterate_method_candidates<T>(
+        &self,
+        db: &impl HirDatabase,
+        krate: Crate,
+        traits_in_scope: &FxHashSet<TraitId>,
+        name: Option<&Name>,
+        mut callback: impl FnMut(&Ty, Function) -> Option<T>,
+    ) -> Option<T> {
+        // There should be no inference vars in types passed here
+        // FIXME check that?
+        // FIXME replace Unknown by bound vars here
+        let canonical = Canonical { value: self.ty.value.clone(), num_vars: 0 };
+
+        let env = self.ty.environment.clone();
+        let krate = krate.id;
+
+        method_resolution::iterate_method_candidates(
+            &canonical,
+            db,
+            env,
+            krate,
+            traits_in_scope,
+            name,
+            method_resolution::LookupMode::MethodCall,
+            |ty, it| match it {
+                AssocItemId::FunctionId(f) => callback(ty, f.into()),
+                _ => None,
+            },
+        )
+    }
+
+    pub fn iterate_path_candidates<T>(
+        &self,
+        db: &impl HirDatabase,
+        krate: Crate,
+        traits_in_scope: &FxHashSet<TraitId>,
+        name: Option<&Name>,
+        mut callback: impl FnMut(&Ty, AssocItem) -> Option<T>,
+    ) -> Option<T> {
+        // There should be no inference vars in types passed here
+        // FIXME check that?
+        // FIXME replace Unknown by bound vars here
+        let canonical = Canonical { value: self.ty.value.clone(), num_vars: 0 };
+
+        let env = self.ty.environment.clone();
+        let krate = krate.id;
+
+        method_resolution::iterate_method_candidates(
+            &canonical,
+            db,
+            env,
+            krate,
+            traits_in_scope,
+            name,
+            method_resolution::LookupMode::Path,
+            |ty, it| callback(ty, it.into()),
+        )
+    }
+
     pub fn as_adt(&self) -> Option<Adt> {
         let (adt, _subst) = self.ty.value.as_adt()?;
         Some(adt.into())
diff --git a/crates/ra_hir/src/source_analyzer.rs b/crates/ra_hir/src/source_analyzer.rs
index 3df48842d..76e0bff34 100644
--- a/crates/ra_hir/src/source_analyzer.rs
+++ b/crates/ra_hir/src/source_analyzer.rs
@@ -16,12 +16,12 @@ use hir_def::{
     expr::{ExprId, PatId},
     nameres::ModuleSource,
     resolver::{self, resolver_for_scope, HasResolver, Resolver, TypeNs, ValueNs},
-    AssocItemId, DefWithBodyId,
+    DefWithBodyId, TraitId,
 };
 use hir_expand::{
     hygiene::Hygiene, name::AsName, AstId, HirFileId, InFile, MacroCallId, MacroCallKind,
 };
-use hir_ty::{method_resolution, Canonical, InEnvironment, InferenceResult, TraitEnvironment, Ty};
+use hir_ty::{InEnvironment, InferenceResult, TraitEnvironment};
 use ra_prof::profile;
 use ra_syntax::{
     ast::{self, AstNode},
@@ -29,11 +29,11 @@ use ra_syntax::{
     SyntaxKind::*,
     SyntaxNode, SyntaxNodePtr, SyntaxToken, TextRange, TextUnit,
 };
+use rustc_hash::FxHashSet;
 
 use crate::{
-    db::HirDatabase, Adt, AssocItem, Const, DefWithBody, Enum, EnumVariant, FromSource, Function,
-    ImplBlock, Local, MacroDef, Name, Path, ScopeDef, Static, Struct, Trait, Type, TypeAlias,
-    TypeParam,
+    db::HirDatabase, Adt, Const, DefWithBody, Enum, EnumVariant, FromSource, Function, ImplBlock,
+    Local, MacroDef, Name, Path, ScopeDef, Static, Struct, Trait, Type, TypeAlias, TypeParam,
 };
 
 /// `SourceAnalyzer` is a convenience wrapper which exposes HIR API in terms of
@@ -347,49 +347,9 @@ impl SourceAnalyzer {
             .collect()
     }
 
-    pub fn iterate_method_candidates<T>(
-        &self,
-        db: &impl HirDatabase,
-        ty: &Type,
-        name: Option<&Name>,
-        mut callback: impl FnMut(&Ty, Function) -> Option<T>,
-    ) -> Option<T> {
-        // There should be no inference vars in types passed here
-        // FIXME check that?
-        // FIXME replace Unknown by bound vars here
-        let canonical = Canonical { value: ty.ty.value.clone(), num_vars: 0 };
-        method_resolution::iterate_method_candidates(
-            &canonical,
-            db,
-            &self.resolver,
-            name,
-            method_resolution::LookupMode::MethodCall,
-            |ty, it| match it {
-                AssocItemId::FunctionId(f) => callback(ty, f.into()),
-                _ => None,
-            },
-        )
-    }
-
-    pub fn iterate_path_candidates<T>(
-        &self,
-        db: &impl HirDatabase,
-        ty: &Type,
-        name: Option<&Name>,
-        mut callback: impl FnMut(&Ty, AssocItem) -> Option<T>,
-    ) -> Option<T> {
-        // There should be no inference vars in types passed here
-        // FIXME check that?
-        // FIXME replace Unknown by bound vars here
-        let canonical = Canonical { value: ty.ty.value.clone(), num_vars: 0 };
-        method_resolution::iterate_method_candidates(
-            &canonical,
-            db,
-            &self.resolver,
-            name,
-            method_resolution::LookupMode::Path,
-            |ty, it| callback(ty, it.into()),
-        )
+    /// Note: `FxHashSet<TraitId>` should be treated as an opaque type, passed into `Type
+    pub fn traits_in_scope(&self, db: &impl HirDatabase) -> FxHashSet<TraitId> {
+        self.resolver.traits_in_scope(db)
     }
 
     pub fn expand(
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);
 
diff --git a/crates/ra_ide/src/completion/complete_dot.rs b/crates/ra_ide/src/completion/complete_dot.rs
index 9ab43644e..2ca78c927 100644
--- a/crates/ra_ide/src/completion/complete_dot.rs
+++ b/crates/ra_ide/src/completion/complete_dot.rs
@@ -53,13 +53,16 @@ fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: &Ty
 }
 
 fn complete_methods(acc: &mut Completions, ctx: &CompletionContext, receiver: &Type) {
-    let mut seen_methods = FxHashSet::default();
-    ctx.analyzer.iterate_method_candidates(ctx.db, receiver, None, |_ty, func| {
-        if func.has_self_param(ctx.db) && seen_methods.insert(func.name(ctx.db)) {
-            acc.add_function(ctx, func);
-        }
-        None::<()>
-    });
+    if let Some(krate) = ctx.module.map(|it| it.krate()) {
+        let mut seen_methods = FxHashSet::default();
+        let traits_in_scope = ctx.analyzer.traits_in_scope(ctx.db);
+        receiver.iterate_method_candidates(ctx.db, krate, &traits_in_scope, None, |_ty, func| {
+            if func.has_self_param(ctx.db) && seen_methods.insert(func.name(ctx.db)) {
+                acc.add_function(ctx, func);
+            }
+            None::<()>
+        });
+    }
 }
 
 #[cfg(test)]
diff --git a/crates/ra_ide/src/completion/complete_path.rs b/crates/ra_ide/src/completion/complete_path.rs
index 0dce9dc2d..af24e9f48 100644
--- a/crates/ra_ide/src/completion/complete_path.rs
+++ b/crates/ra_ide/src/completion/complete_path.rs
@@ -49,22 +49,24 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) {
                 hir::ModuleDef::TypeAlias(a) => a.ty(ctx.db),
                 _ => unreachable!(),
             };
-            ctx.analyzer.iterate_path_candidates(ctx.db, &ty, None, |_ty, item| {
-                match item {
-                    hir::AssocItem::Function(func) => {
-                        if !func.has_self_param(ctx.db) {
-                            acc.add_function(ctx, func);
-                        }
-                    }
-                    hir::AssocItem::Const(ct) => acc.add_const(ctx, ct),
-                    hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
-                }
-                None::<()>
-            });
             // Iterate assoc types separately
             // FIXME: complete T::AssocType
             let krate = ctx.module.map(|m| m.krate());
             if let Some(krate) = krate {
+                let traits_in_scope = ctx.analyzer.traits_in_scope(ctx.db);
+                ty.iterate_path_candidates(ctx.db, krate, &traits_in_scope, None, |_ty, item| {
+                    match item {
+                        hir::AssocItem::Function(func) => {
+                            if !func.has_self_param(ctx.db) {
+                                acc.add_function(ctx, func);
+                            }
+                        }
+                        hir::AssocItem::Const(ct) => acc.add_const(ctx, ct),
+                        hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
+                    }
+                    None::<()>
+                });
+
                 ty.iterate_impl_items(ctx.db, krate, |item| {
                     match item {
                         hir::AssocItem::Function(_) | hir::AssocItem::Const(_) => {}