From ff4d73b9f4315b4d102e1043e0a6ab5694074d3e Mon Sep 17 00:00:00 2001
From: Wilco Kusee <wilcokusee@gmail.com>
Date: Thu, 11 Mar 2021 20:15:28 +0100
Subject: [PATCH] Add binders from trait

---
 .../src/lowering/program_lowerer.rs           | 20 +++++++++++++------
 chalk-solve/src/display/items.rs              |  2 +-
 chalk-solve/src/logging_db/id_collector.rs    |  2 +-
 chalk-solve/src/rust_ir.rs                    | 17 +++++++++++-----
 4 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/chalk-integration/src/lowering/program_lowerer.rs b/chalk-integration/src/lowering/program_lowerer.rs
index e5d477981cb..22a39db869d 100644
--- a/chalk-integration/src/lowering/program_lowerer.rs
+++ b/chalk-integration/src/lowering/program_lowerer.rs
@@ -340,6 +340,16 @@ impl ProgramLowerer {
                             AssocItemDefn::Const(assoc_const_defn) => {
                                 let lookup = &self.associated_const_lookups
                                     [&(trait_id, assoc_const_defn.name.str.clone())];
+
+                                let variable_kinds = trait_defn.all_parameters();
+                                let binders = assoc_const_defn
+                                    .value
+                                    .as_ref()
+                                    .map(|value| {
+                                        empty_env
+                                            .in_binders(variable_kinds, |env| value.lower(&env))
+                                    })
+                                    .transpose()?;
                                 associated_const_data.insert(
                                     lookup.id,
                                     Arc::new(rust_ir::AssociatedConstDatum {
@@ -347,11 +357,7 @@ impl ProgramLowerer {
                                         id: lookup.id,
                                         name: assoc_const_defn.name.str.clone(),
                                         ty: assoc_const_defn.ty.lower(&empty_env)?,
-                                        value: assoc_const_defn
-                                            .value
-                                            .clone()
-                                            .map(|v| v.lower(&empty_env))
-                                            .transpose()?,
+                                        binders,
                                     }),
                                 );
                             }
@@ -409,7 +415,9 @@ impl ProgramLowerer {
                                 let lookup = &self.associated_const_lookups
                                     [&(trait_id, acv.name.str.clone())];
 
-                                let value = acv.value.lower(&empty_env)?;
+                                let variable_kinds = impl_defn.all_parameters();
+                                let value = empty_env
+                                    .in_binders(variable_kinds, |env| acv.value.lower(env))?;
                                 associated_const_values.insert(
                                     acv_id,
                                     Arc::new(rust_ir::AssociatedConstValue {
diff --git a/chalk-solve/src/display/items.rs b/chalk-solve/src/display/items.rs
index a25f141cbb1..2967fd32375 100644
--- a/chalk-solve/src/display/items.rs
+++ b/chalk-solve/src/display/items.rs
@@ -485,7 +485,7 @@ impl<I: Interner> RenderAsRust<I> for AssociatedConstValue<I> {
 
         write!(f, "{}const {}", s.indent(), assoc_const_data.id.display(s))?;
         write!(f, ": {}", assoc_const_data.ty.display(s))?;
-        write!(f, " = {};", self.value.display(s))?;
+        write!(f, " = {};", self.value.skip_binders().display(s))?;
         Ok(())
     }
 }
diff --git a/chalk-solve/src/logging_db/id_collector.rs b/chalk-solve/src/logging_db/id_collector.rs
index f820a80f8da..dc127ceb138 100644
--- a/chalk-solve/src/logging_db/id_collector.rs
+++ b/chalk-solve/src/logging_db/id_collector.rs
@@ -9,7 +9,7 @@ use chalk_ir::{
 use std::collections::BTreeSet;
 
 /// Collects the identifiers needed to resolve all the names for a given
-/// set of identifers, excluding identifiers we already have.
+/// set of identifiers, excluding identifiers we already have.
 ///
 /// When recording identifiers to print, the `LoggingRustIrDatabase` only
 /// records identifiers the solver uses. But the solver assumes well-formedness,
diff --git a/chalk-solve/src/rust_ir.rs b/chalk-solve/src/rust_ir.rs
index 4af82a110c2..b770c5a866e 100644
--- a/chalk-solve/src/rust_ir.rs
+++ b/chalk-solve/src/rust_ir.rs
@@ -514,7 +514,13 @@ impl<I: Interner> Visit<I> for AssociatedTyDatum<I> {
     }
 }
 
-/// Represents an associated const declaration found inside of a trait.
+/// Represents an associated const declaration found inside of a trait:
+///
+/// ```notrust
+/// trait Foo<P1..Pn> { // P0 is Self
+///     const Bar: [type] (= [const]);
+/// }
+/// ```
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub struct AssociatedConstDatum<I: Interner> {
     /// The trait this associated const is defined in.
@@ -529,8 +535,9 @@ pub struct AssociatedConstDatum<I: Interner> {
     /// Type of this associated const.
     pub ty: Ty<I>,
 
-    /// Value of this associated const.
-    pub value: Option<Const<I>>,
+    /// Value of this associated const with variables `P0...Pn`
+    /// from the trait the assoc const is in.
+    pub binders: Option<Binders<Const<I>>>,
 }
 
 // Manual implementation to avoid I::Identifier type.
@@ -546,7 +553,7 @@ impl<I: Interner> Visit<I> for AssociatedConstDatum<I> {
         try_break!(self.trait_id.visit_with(visitor, outer_binder));
         try_break!(self.id.visit_with(visitor, outer_binder));
         try_break!(self.ty.visit_with(visitor, outer_binder));
-        self.value.visit_with(visitor, outer_binder)
+        self.binders.visit_with(visitor, outer_binder)
     }
 }
 
@@ -663,7 +670,7 @@ pub struct AssociatedTyValueBound<I: Interner> {
 pub struct AssociatedConstValue<I: Interner> {
     pub impl_id: ImplId<I>,
     pub associated_const_id: AssocConstId<I>,
-    pub value: Const<I>,
+    pub value: Binders<Const<I>>,
 }
 
 /// Represents the bounds for an `impl Trait` type.