5 files changed, 63 insertions, 49 deletions

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 821f919d4..9930cff66 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -9,7 +9,7 @@ use hir_def::{
     builtin_type::BuiltinType,
     docs::Documentation,
     per_ns::PerNs,
-    resolver::{HasResolver, TypeNs},
+    resolver::HasResolver,
     type_ref::{Mutability, TypeRef},
     AdtId, AstItemDef, ConstId, ContainerId, DefWithBodyId, EnumId, FunctionId, GenericDefId,
     HasModule, ImplId, LocalEnumVariantId, LocalImportId, LocalModuleId, LocalStructFieldId,
@@ -28,8 +28,8 @@ use crate::{
     expr::{BindingAnnotation, Body, BodySourceMap, ExprValidator, Pat, PatId},
     ty::display::HirFormatter,
     ty::{
-        self, InEnvironment, InferenceResult, Namespace, TraitEnvironment, TraitRef, Ty, TypeCtor,
-        TypeWalk,
+        self, utils::all_super_traits, InEnvironment, InferenceResult, Namespace, TraitEnvironment,
+        TraitRef, Ty, TypeCtor, TypeWalk,
     },
     CallableDef, Either, HirDisplay, Name, Source,
 };
@@ -740,48 +740,6 @@ impl Trait {
         db.trait_data(self.id).items.iter().map(|it| (*it).into()).collect()
     }
 
-    fn direct_super_traits(self, db: &impl HirDatabase) -> Vec<Trait> {
-        let resolver = self.id.resolver(db);
-        // returning the iterator directly doesn't easily work because of
-        // lifetime problems, but since there usually shouldn't be more than a
-        // few direct traits this should be fine (we could even use some kind of
-        // SmallVec if performance is a concern)
-        db.generic_params(self.id.into())
-            .where_predicates
-            .iter()
-            .filter_map(|pred| match &pred.type_ref {
-                TypeRef::Path(p) if p.as_ident() == Some(&name::SELF_TYPE) => pred.bound.as_path(),
-                _ => None,
-            })
-            .filter_map(|path| match resolver.resolve_path_in_type_ns_fully(db, path) {
-                Some(TypeNs::TraitId(t)) => Some(t),
-                _ => None,
-            })
-            .map(Trait::from)
-            .collect()
-    }
-
-    /// Returns an iterator over the whole super trait hierarchy (including the
-    /// trait itself).
-    pub fn all_super_traits(self, db: &impl HirDatabase) -> Vec<Trait> {
-        // we need to take care a bit here to avoid infinite loops in case of cycles
-        // (i.e. if we have `trait A: B; trait B: A;`)
-        let mut result = vec![self];
-        let mut i = 0;
-        while i < result.len() {
-            let t = result[i];
-            // yeah this is quadratic, but trait hierarchies should be flat
-            // enough that this doesn't matter
-            for tt in t.direct_super_traits(db) {
-                if !result.contains(&tt) {
-                    result.push(tt);
-                }
-            }
-            i += 1;
-        }
-        result
-    }
-
     pub fn associated_type_by_name(self, db: &impl DefDatabase, name: &Name) -> Option<TypeAlias> {
         let trait_data = db.trait_data(self.id);
         let res =
@@ -794,7 +752,10 @@ impl Trait {
         db: &impl HirDatabase,
         name: &Name,
     ) -> Option<TypeAlias> {
-        self.all_super_traits(db).into_iter().find_map(|t| t.associated_type_by_name(db, name))
+        all_super_traits(db, self.id)
+            .into_iter()
+            .map(Trait::from)
+            .find_map(|t| t.associated_type_by_name(db, name))
     }
 
     pub fn trait_ref(self, db: &impl HirDatabase) -> TraitRef {
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index bd03055b9..2a2dc26b4 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -9,6 +9,7 @@ mod op;
 mod lower;
 mod infer;
 pub(crate) mod display;
+pub(crate) mod utils;
 
 #[cfg(test)]
 mod tests;
diff --git a/crates/ra_hir/src/ty/lower.rs b/crates/ra_hir/src/ty/lower.rs
index 2d23890a5..9e3afabe0 100644
--- a/crates/ra_hir/src/ty/lower.rs
+++ b/crates/ra_hir/src/ty/lower.rs
@@ -28,6 +28,7 @@ use crate::{
     db::HirDatabase,
     ty::{
         primitive::{FloatTy, IntTy},
+        utils::all_super_traits,
         Adt,
     },
     util::make_mut_slice,
@@ -260,7 +261,7 @@ impl Ty {
             GenericPredicate::Implemented(tr) if tr.self_ty() == &self_ty => Some(tr.trait_),
             _ => None,
         });
-        let traits = traits_from_env.flat_map(|t| t.all_super_traits(db));
+        let traits = traits_from_env.flat_map(|t| all_super_traits(db, t.id)).map(Trait::from);
         for t in traits {
             if let Some(associated_ty) = t.associated_type_by_name(db, &segment.name) {
                 let substs = Substs::build_for_def(db, t.id)
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index 489fcd64b..0e18684ed 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -16,7 +16,7 @@ use rustc_hash::FxHashMap;
 use crate::{
     db::HirDatabase,
     ty::primitive::{FloatBitness, Uncertain},
-    ty::{Ty, TypeCtor},
+    ty::{utils::all_super_traits, Ty, TypeCtor},
     AssocItem, Crate, Function, Mutability, Name, Trait,
 };
 
@@ -249,7 +249,8 @@ fn iterate_trait_method_candidates<T>(
     let traits_from_env = env
         .trait_predicates_for_self_ty(&ty.value)
         .map(|tr| tr.trait_)
-        .flat_map(|t| t.all_super_traits(db));
+        .flat_map(|t| all_super_traits(db, t.id))
+        .map(Trait::from);
     let traits = inherent_trait
         .chain(traits_from_env)
         .chain(resolver.traits_in_scope(db).into_iter().map(Trait::from));
diff --git a/crates/ra_hir/src/ty/utils.rs b/crates/ra_hir/src/ty/utils.rs
new file mode 100644
index 000000000..345fa9430
--- /dev/null
+++ b/crates/ra_hir/src/ty/utils.rs
@@ -0,0 +1,50 @@
+use hir_def::{
+    db::DefDatabase,
+    resolver::{HasResolver, TypeNs},
+    type_ref::TypeRef,
+    TraitId,
+};
+use hir_expand::name;
+
+// FIXME: this is wrong, b/c it can't express `trait T: PartialEq<()>`.
+// We should return a `TraitREf` here.
+fn direct_super_traits(db: &impl DefDatabase, trait_: TraitId) -> Vec<TraitId> {
+    let resolver = trait_.resolver(db);
+    // returning the iterator directly doesn't easily work because of
+    // lifetime problems, but since there usually shouldn't be more than a
+    // few direct traits this should be fine (we could even use some kind of
+    // SmallVec if performance is a concern)
+    db.generic_params(trait_.into())
+        .where_predicates
+        .iter()
+        .filter_map(|pred| match &pred.type_ref {
+            TypeRef::Path(p) if p.as_ident() == Some(&name::SELF_TYPE) => pred.bound.as_path(),
+            _ => None,
+        })
+        .filter_map(|path| match resolver.resolve_path_in_type_ns_fully(db, path) {
+            Some(TypeNs::TraitId(t)) => Some(t),
+            _ => None,
+        })
+        .collect()
+}
+
+/// Returns an iterator over the whole super trait hierarchy (including the
+/// trait itself).
+pub(crate) fn all_super_traits(db: &impl DefDatabase, trait_: TraitId) -> Vec<TraitId> {
+    // we need to take care a bit here to avoid infinite loops in case of cycles
+    // (i.e. if we have `trait A: B; trait B: A;`)
+    let mut result = vec![trait_];
+    let mut i = 0;
+    while i < result.len() {
+        let t = result[i];
+        // yeah this is quadratic, but trait hierarchies should be flat
+        // enough that this doesn't matter
+        for tt in direct_super_traits(db, t) {
+            if !result.contains(&tt) {
+                result.push(tt);
+            }
+        }
+        i += 1;
+    }
+    result
+}