7 files changed, 52 insertions, 20 deletions

diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 9d46f9025..e0a37e13d 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -224,7 +224,7 @@ pub trait HirDatabase: DefDatabase + AstDatabase {
     fn normalize(
         &self,
         krate: Crate,
-        goal: crate::ty::Canonical<crate::ty::ProjectionPredicate>,
+        goal: crate::ty::Canonical<crate::ty::InEnvironment<crate::ty::ProjectionPredicate>>,
     ) -> Option<crate::ty::traits::Solution>;
 }
 
diff --git a/crates/ra_hir/src/ty/autoderef.rs b/crates/ra_hir/src/ty/autoderef.rs
index 90c1ae630..214aa7d03 100644
--- a/crates/ra_hir/src/ty/autoderef.rs
+++ b/crates/ra_hir/src/ty/autoderef.rs
@@ -52,6 +52,8 @@ fn deref_by_trait(
 
     // FIXME make the Canonical handling nicer
 
+    let env = super::lower::trait_env(db, resolver);
+
     let projection = super::traits::ProjectionPredicate {
         ty: Ty::Bound(0),
         projection_ty: super::ProjectionTy {
@@ -60,7 +62,9 @@ fn deref_by_trait(
         },
     };
 
-    let canonical = super::Canonical { num_vars: 1 + ty.num_vars, value: projection };
+    let in_env = super::traits::InEnvironment { value: projection, environment: env };
+
+    let canonical = super::Canonical { num_vars: 1 + ty.num_vars, value: in_env };
 
     let solution = db.normalize(krate, canonical)?;
 
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index f8839ebd2..f6cf61ad2 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -356,7 +356,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     };
                 }
                 Obligation::Projection(pr) => {
-                    let canonicalized = self.canonicalizer().canonicalize_projection(pr.clone());
+                    let in_env = InEnvironment::new(self.trait_env.clone(), pr.clone());
+                    let canonicalized = self.canonicalizer().canonicalize_projection(in_env);
                     let solution = self
                         .db
                         .normalize(self.resolver.krate().unwrap(), canonicalized.value.clone());
diff --git a/crates/ra_hir/src/ty/infer/unify.rs b/crates/ra_hir/src/ty/infer/unify.rs
index ad2eefcaf..2ed326cd5 100644
--- a/crates/ra_hir/src/ty/infer/unify.rs
+++ b/crates/ra_hir/src/ty/infer/unify.rs
@@ -129,10 +129,14 @@ where
 
     pub fn canonicalize_projection(
         mut self,
-        projection: ProjectionPredicate,
-    ) -> Canonicalized<ProjectionPredicate> {
-        let result = self.do_canonicalize_projection_predicate(projection);
-        self.into_canonicalized(result)
+        projection: InEnvironment<ProjectionPredicate>,
+    ) -> Canonicalized<InEnvironment<ProjectionPredicate>> {
+        let result = self.do_canonicalize_projection_predicate(projection.value);
+        // FIXME canonicalize env
+        self.into_canonicalized(InEnvironment {
+            value: result,
+            environment: projection.environment,
+        })
     }
 }
 
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 594e82af2..7340bb9bd 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -3010,6 +3010,25 @@ fn test<T>(t: T) { t.foo()<|>; }
     assert_eq!(t, "{unknown}");
 }
 
+#[test]
+fn generic_param_env_deref() {
+    let t = type_at(
+        r#"
+//- /main.rs
+#[lang = "deref"]
+trait Deref {
+    type Target;
+}
+trait Trait {}
+impl<T> Deref for T where T: Trait {
+    type Target = i128;
+}
+fn test<T: Trait>(t: T) { (*t)<|>; }
+"#,
+    );
+    assert_eq!(t, "i128");
+}
+
 fn type_at_pos(db: &MockDatabase, pos: FilePosition) -> String {
     let file = db.parse(pos.file_id).ok().unwrap();
     let expr = algo::find_node_at_offset::<ast::Expr>(file.syntax(), pos.offset).unwrap();
diff --git a/crates/ra_hir/src/ty/traits.rs b/crates/ra_hir/src/ty/traits.rs
index e0c93550a..01f350bc1 100644
--- a/crates/ra_hir/src/ty/traits.rs
+++ b/crates/ra_hir/src/ty/traits.rs
@@ -134,20 +134,9 @@ pub(crate) fn implements_query(
 pub(crate) fn normalize_query(
     db: &impl HirDatabase,
     krate: Crate,
-    projection: Canonical<ProjectionPredicate>,
+    projection: Canonical<InEnvironment<ProjectionPredicate>>,
 ) -> Option<Solution> {
-    let goal: chalk_ir::Goal = chalk_ir::Normalize {
-        projection: projection.value.projection_ty.to_chalk(db),
-        ty: projection.value.ty.to_chalk(db),
-    }
-    .cast();
-    debug!("goal: {:?}", goal);
-    // FIXME unify with `implements`
-    let env = chalk_ir::Environment::new();
-    let in_env = chalk_ir::InEnvironment::new(&env, goal);
-    let parameter = chalk_ir::ParameterKind::Ty(chalk_ir::UniverseIndex::ROOT);
-    let canonical =
-        chalk_ir::Canonical { value: in_env, binders: vec![parameter; projection.num_vars] };
+    let canonical = projection.to_chalk(db).cast();
     // We currently don't deal with universes (I think / hope they're not yet
     // relevant for our use cases?)
     let u_canonical = chalk_ir::UCanonical { canonical, universes: 1 };
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index f36ff2fc6..32a45731d 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -218,6 +218,21 @@ impl ToChalk for ProjectionTy {
     }
 }
 
+impl ToChalk for super::ProjectionPredicate {
+    type Chalk = chalk_ir::Normalize;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Normalize {
+        chalk_ir::Normalize {
+            projection: self.projection_ty.to_chalk(db),
+            ty: self.ty.to_chalk(db),
+        }
+    }
+
+    fn from_chalk(_db: &impl HirDatabase, _normalize: chalk_ir::Normalize) -> Self {
+        unimplemented!()
+    }
+}
+
 impl<T> ToChalk for Canonical<T>
 where
     T: ToChalk,