Elaborate AliasEq goals

Author: nathanwhit

chalk-solve/src/clauses/env_elaborator.rs

@@ -1,11 +1,13 @@
 use super::program_clauses::ToProgramClauses;
 use crate::clauses::builder::ClauseBuilder;
 use crate::clauses::{match_alias_ty, match_type_name};
+use crate::AliasEq;
 use crate::DomainGoal;
 use crate::FromEnv;
 use crate::ProgramClause;
 use crate::RustIrDatabase;
 use crate::Ty;
+use crate::WhereClause;
 use crate::{debug_span, TyData};
 use chalk_ir::interner::Interner;
 use chalk_ir::visit::{Visit, Visitor};
@@ -83,25 +85,32 @@ impl<'me, I: Interner> Visitor<'me, I> for EnvElaborator<'me, I> {
     }
 
     fn visit_domain_goal(&mut self, domain_goal: &DomainGoal<I>, outer_binder: DebruijnIndex) {
-        if let DomainGoal::FromEnv(from_env) = domain_goal {
-            debug_span!("visit_domain_goal", ?from_env);
-            match from_env {
-                FromEnv::Trait(trait_ref) => {
-                    let trait_datum = self.db.trait_datum(trait_ref.trait_id);
+        match domain_goal {
+            DomainGoal::FromEnv(from_env) => {
+                debug_span!("visit_domain_goal", ?from_env);
+                match from_env {
+                    FromEnv::Trait(trait_ref) => {
+                        let trait_datum = self.db.trait_datum(trait_ref.trait_id);
 
-                    trait_datum.to_program_clauses(&mut self.builder, self.environment);
+                        trait_datum.to_program_clauses(&mut self.builder, self.environment);
 
-                    // If we know that `T: Iterator`, then we also know
-                    // things about `<T as Iterator>::Item`, so push those
-                    // implied bounds too:
-                    for &associated_ty_id in &trait_datum.associated_ty_ids {
-                        self.db
-                            .associated_ty_data(associated_ty_id)
-                            .to_program_clauses(&mut self.builder, self.environment);
+                        // If we know that `T: Iterator`, then we also know
+                        // things about `<T as Iterator>::Item`, so push those
+                        // implied bounds too:
+                        for &associated_ty_id in &trait_datum.associated_ty_ids {
+                            self.db
+                                .associated_ty_data(associated_ty_id)
+                                .to_program_clauses(&mut self.builder, self.environment);
+                        }
                     }
+                    FromEnv::Ty(ty) => ty.visit_with(self, outer_binder),
                 }
-                FromEnv::Ty(ty) => ty.visit_with(self, outer_binder),
             }
+            DomainGoal::Holds(WhereClause::AliasEq(AliasEq { alias, ty })) => {
+                match_alias_ty(&mut self.builder, self.environment, alias);
+                ty.visit_with(self, outer_binder);
+            }
+            _ => {}
         }
     }
 }