Unify `normalize` and `implements` to simplify code

9 files changed, 67 insertions, 107 deletions

diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index e0a37e13d..b0c027631 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -213,18 +213,11 @@ pub trait HirDatabase: DefDatabase + AstDatabase {
     #[salsa::invoke(crate::ty::traits::chalk::impl_datum_query)]
     fn impl_datum(&self, krate: Crate, impl_id: chalk_ir::ImplId) -> Arc<chalk_rust_ir::ImplDatum>;
 
-    #[salsa::invoke(crate::ty::traits::implements_query)]
-    fn implements(
+    #[salsa::invoke(crate::ty::traits::solve_query)]
+    fn solve(
         &self,
         krate: Crate,
-        goal: crate::ty::Canonical<crate::ty::InEnvironment<crate::ty::TraitRef>>,
-    ) -> Option<crate::ty::traits::Solution>;
-
-    #[salsa::invoke(crate::ty::traits::normalize_query)]
-    fn normalize(
-        &self,
-        krate: Crate,
-        goal: crate::ty::Canonical<crate::ty::InEnvironment<crate::ty::ProjectionPredicate>>,
+        goal: crate::ty::Canonical<crate::ty::InEnvironment<crate::ty::Obligation>>,
     ) -> Option<crate::ty::traits::Solution>;
 }
 
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index b45a188d1..9accffcbc 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -26,7 +26,7 @@ pub(crate) use lower::{
     callable_item_sig, generic_defaults_query, generic_predicates_query, type_for_def,
     type_for_field, TypableDef,
 };
-pub(crate) use traits::{Environment, InEnvironment, ProjectionPredicate};
+pub(crate) use traits::{Environment, InEnvironment, Obligation, ProjectionPredicate};
 
 /// A type constructor or type name: this might be something like the primitive
 /// type `bool`, a struct like `Vec`, or things like function pointers or
diff --git a/crates/ra_hir/src/ty/autoderef.rs b/crates/ra_hir/src/ty/autoderef.rs
index 214aa7d03..c26513871 100644
--- a/crates/ra_hir/src/ty/autoderef.rs
+++ b/crates/ra_hir/src/ty/autoderef.rs
@@ -62,11 +62,13 @@ fn deref_by_trait(
         },
     };
 
-    let in_env = super::traits::InEnvironment { value: projection, environment: env };
+    let obligation = super::Obligation::Projection(projection);
+
+    let in_env = super::traits::InEnvironment { value: obligation, environment: env };
 
     let canonical = super::Canonical { num_vars: 1 + ty.num_vars, value: in_env };
 
-    let solution = db.normalize(krate, canonical)?;
+    let solution = db.solve(krate, canonical)?;
 
     match &solution {
         Solution::Unique(vars) => {
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index f6cf61ad2..1f74108a4 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -331,53 +331,25 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     fn resolve_obligations_as_possible(&mut self) {
         let obligations = mem::replace(&mut self.obligations, Vec::new());
         for obligation in obligations {
-            match &obligation {
-                Obligation::Trait(tr) => {
-                    let in_env = InEnvironment::new(self.trait_env.clone(), tr.clone());
-                    let canonicalized = self.canonicalizer().canonicalize_trait_ref(in_env);
-                    let solution = self
-                        .db
-                        .implements(self.resolver.krate().unwrap(), canonicalized.value.clone());
-                    match solution {
-                        Some(Solution::Unique(substs)) => {
-                            canonicalized.apply_solution(self, substs.0);
-                        }
-                        Some(Solution::Ambig(Guidance::Definite(substs))) => {
-                            canonicalized.apply_solution(self, substs.0);
-                            self.obligations.push(obligation);
-                        }
-                        Some(_) => {
-                            // FIXME use this when trying to resolve everything at the end
-                            self.obligations.push(obligation);
-                        }
-                        None => {
-                            // FIXME obligation cannot be fulfilled => diagnostic
-                        }
-                    };
+            let in_env = InEnvironment::new(self.trait_env.clone(), obligation.clone());
+            let canonicalized = self.canonicalizer().canonicalize_obligation(in_env);
+            let solution =
+                self.db.solve(self.resolver.krate().unwrap(), canonicalized.value.clone());
+
+            match solution {
+                Some(Solution::Unique(substs)) => {
+                    canonicalized.apply_solution(self, substs.0);
                 }
-                Obligation::Projection(pr) => {
-                    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());
-
-                    match solution {
-                        Some(Solution::Unique(substs)) => {
-                            canonicalized.apply_solution(self, substs.0);
-                        }
-                        Some(Solution::Ambig(Guidance::Definite(substs))) => {
-                            canonicalized.apply_solution(self, substs.0);
-                            self.obligations.push(obligation);
-                        }
-                        Some(_) => {
-                            // FIXME use this when trying to resolve everything at the end
-                            self.obligations.push(obligation);
-                        }
-                        None => {
-                            // FIXME obligation cannot be fulfilled => diagnostic
-                        }
-                    };
+                Some(Solution::Ambig(Guidance::Definite(substs))) => {
+                    canonicalized.apply_solution(self, substs.0);
+                    self.obligations.push(obligation);
+                }
+                Some(_) => {
+                    // FIXME use this when trying to resolve everything at the end
+                    self.obligations.push(obligation);
+                }
+                None => {
+                    // FIXME obligation cannot be fulfilled => diagnostic
                 }
             };
         }
diff --git a/crates/ra_hir/src/ty/infer/unify.rs b/crates/ra_hir/src/ty/infer/unify.rs
index 2ed326cd5..e7e8825d1 100644
--- a/crates/ra_hir/src/ty/infer/unify.rs
+++ b/crates/ra_hir/src/ty/infer/unify.rs
@@ -1,6 +1,6 @@
 //! Unification and canonicalization logic.
 
-use super::InferenceContext;
+use super::{InferenceContext, Obligation};
 use crate::db::HirDatabase;
 use crate::ty::{
     Canonical, InEnvironment, InferTy, ProjectionPredicate, ProjectionTy, TraitRef, Ty,
@@ -110,32 +110,24 @@ where
     // FIXME: add some point, we need to introduce a `Fold` trait that abstracts
     // over all the things that can be canonicalized (like Chalk and rustc have)
 
-    pub fn canonicalize_ty(mut self, ty: Ty) -> Canonicalized<Ty> {
+    pub(crate) fn canonicalize_ty(mut self, ty: Ty) -> Canonicalized<Ty> {
         let result = self.do_canonicalize_ty(ty);
         self.into_canonicalized(result)
     }
 
-    pub fn canonicalize_trait_ref(
+    pub(crate) fn canonicalize_obligation(
         mut self,
-        trait_ref_in_env: InEnvironment<TraitRef>,
-    ) -> Canonicalized<InEnvironment<TraitRef>> {
-        let result = self.do_canonicalize_trait_ref(trait_ref_in_env.value);
-        // FIXME canonicalize env
-        self.into_canonicalized(InEnvironment {
-            value: result,
-            environment: trait_ref_in_env.environment,
-        })
-    }
-
-    pub fn canonicalize_projection(
-        mut self,
-        projection: InEnvironment<ProjectionPredicate>,
-    ) -> Canonicalized<InEnvironment<ProjectionPredicate>> {
-        let result = self.do_canonicalize_projection_predicate(projection.value);
-        // FIXME canonicalize env
+        obligation: InEnvironment<Obligation>,
+    ) -> Canonicalized<InEnvironment<Obligation>> {
+        let result = match obligation.value {
+            Obligation::Trait(tr) => Obligation::Trait(self.do_canonicalize_trait_ref(tr)),
+            Obligation::Projection(pr) => {
+                Obligation::Projection(self.do_canonicalize_projection_predicate(pr))
+            }
+        };
         self.into_canonicalized(InEnvironment {
             value: result,
-            environment: projection.environment,
+            environment: obligation.environment,
         })
     }
 }
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index 40f5eabf0..e214bf1af 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -211,8 +211,8 @@ fn iterate_trait_method_candidates<T>(
                 let data = m.data(db);
                 if name.map_or(true, |name| data.name() == name) && data.has_self_param() {
                     if !known_implemented {
-                        let trait_ref = canonical_trait_ref(db, env.clone(), t, ty.clone());
-                        if db.implements(krate, trait_ref).is_none() {
+                        let goal = generic_implements_goal(db, env.clone(), t, ty.clone());
+                        if db.solve(krate, goal).is_none() {
                             continue 'traits;
                         }
                     }
@@ -279,12 +279,12 @@ impl Ty {
 
 /// This creates Substs for a trait with the given Self type and type variables
 /// for all other parameters, to query Chalk with it.
-fn canonical_trait_ref(
+fn generic_implements_goal(
     db: &impl HirDatabase,
     env: Arc<Environment>,
     trait_: Trait,
     self_ty: Canonical<Ty>,
-) -> Canonical<InEnvironment<TraitRef>> {
+) -> Canonical<InEnvironment<super::Obligation>> {
     let mut substs = Vec::new();
     let generics = trait_.generic_params(db);
     let num_vars = self_ty.num_vars;
@@ -297,8 +297,8 @@ fn canonical_trait_ref(
             .enumerate()
             .map(|(i, _p)| Ty::Bound((i + num_vars) as u32)),
     );
-    Canonical {
-        num_vars: substs.len() - 1 + self_ty.num_vars,
-        value: InEnvironment::new(env, TraitRef { trait_, substs: substs.into() }),
-    }
+    let num_vars = substs.len() - 1 + self_ty.num_vars;
+    let trait_ref = TraitRef { trait_, substs: substs.into() };
+    let obligation = super::Obligation::Trait(trait_ref);
+    Canonical { num_vars, value: InEnvironment::new(env, obligation) }
 }
diff --git a/crates/ra_hir/src/ty/traits.rs b/crates/ra_hir/src/ty/traits.rs
index 01f350bc1..d99843319 100644
--- a/crates/ra_hir/src/ty/traits.rs
+++ b/crates/ra_hir/src/ty/traits.rs
@@ -93,7 +93,7 @@ impl<T> InEnvironment<T> {
 /// Something that needs to be proven (by Chalk) during type checking, e.g. that
 /// a certain type implements a certain trait. Proving the Obligation might
 /// result in additional information about inference variables.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub enum Obligation {
     /// Prove that a certain type implements a trait (the type is the `Self` type
     /// parameter to the `TraitRef`).
@@ -116,11 +116,11 @@ pub struct ProjectionPredicate {
     pub ty: Ty,
 }
 
-/// Check using Chalk whether trait is implemented for given parameters including `Self` type.
-pub(crate) fn implements_query(
+/// Solve a trait goal using Chalk.
+pub(crate) fn solve_query(
     db: &impl HirDatabase,
     krate: Crate,
-    trait_ref: Canonical<InEnvironment<TraitRef>>,
+    trait_ref: Canonical<InEnvironment<Obligation>>,
 ) -> Option<Solution> {
     let _p = profile("implements_query");
     let canonical = trait_ref.to_chalk(db).cast();
@@ -131,19 +131,6 @@ pub(crate) fn implements_query(
     solution.map(|solution| solution_from_chalk(db, solution))
 }
 
-pub(crate) fn normalize_query(
-    db: &impl HirDatabase,
-    krate: Crate,
-    projection: Canonical<InEnvironment<ProjectionPredicate>>,
-) -> Option<Solution> {
-    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 };
-    let solution = solve(db, krate, &u_canonical);
-    solution.map(|solution| solution_from_chalk(db, solution))
-}
-
 fn solution_from_chalk(db: &impl HirDatabase, solution: chalk_solve::Solution) -> Solution {
     let convert_subst = |subst: chalk_ir::Canonical<chalk_ir::Substitution>| {
         let value = subst
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index 32a45731d..2df4dd13f 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -12,7 +12,7 @@ use chalk_rust_ir::{AssociatedTyDatum, ImplDatum, StructDatum, TraitDatum};
 use ra_db::salsa::{InternId, InternKey};
 use test_utils::tested_by;
 
-use super::{Canonical, ChalkContext};
+use super::{Canonical, ChalkContext, Obligation};
 use crate::{
     db::HirDatabase,
     generics::GenericDef,
@@ -233,6 +233,21 @@ impl ToChalk for super::ProjectionPredicate {
     }
 }
 
+impl ToChalk for Obligation {
+    type Chalk = chalk_ir::DomainGoal;
+
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::DomainGoal {
+        match self {
+            Obligation::Trait(tr) => tr.to_chalk(db).cast(),
+            Obligation::Projection(pr) => pr.to_chalk(db).cast(),
+        }
+    }
+
+    fn from_chalk(_db: &impl HirDatabase, _goal: chalk_ir::DomainGoal) -> Self {
+        unimplemented!()
+    }
+}
+
 impl<T> ToChalk for Canonical<T>
 where
     T: ToChalk,
diff --git a/crates/ra_ide_api/src/change.rs b/crates/ra_ide_api/src/change.rs
index 2a1af0a0a..efc9a92de 100644
--- a/crates/ra_ide_api/src/change.rs
+++ b/crates/ra_ide_api/src/change.rs
@@ -295,8 +295,7 @@ impl RootDatabase {
             hir::db::TraitDatumQuery
             hir::db::StructDatumQuery
             hir::db::ImplDatumQuery
-            hir::db::ImplementsQuery
-            hir::db::NormalizeQuery
+            hir::db::SolveQuery
         ];
         acc.sort_by_key(|it| std::cmp::Reverse(it.1));
         acc