gccrs: Support type resolution on super traits on dyn objects

When checking if specified bounds satisfy other bounds we must lookup the
super traits. To finish the support for super traits we need to redo the
computation of method addresses to support super traits.

Addresses #914

gcc/rust/ChangeLog:

	* backend/rust-compile.cc: Add note about missing support for super
	traits.
	* typecheck/rust-tyty.cc (BaseType::satisfies_bound): New function.
	(BaseType::bounds_compatible): New function.
	(DynamicObjectType::get_object_items): New function.
	* typecheck/rust-hir-trait-ref.h: Use new API to perform type resolution
	on dyn objects.

gcc/rust/backend/rust-compile.cc

@@ -247,6 +247,8 @@ HIRCompileBase::compute_address_for_trait_item (
   // Algo:
   // check if there is an impl-item for this trait-item-ref first
   // else assert that the trait-item-ref has an implementation
+  //
+  // FIXME this does not support super traits
 
   TyTy::TypeBoundPredicateItem predicate_item
     = predicate->lookup_associated_item (ref->get_identifier ());

gcc/rust/typecheck/rust-hir-trait-ref.h

@@ -380,6 +380,16 @@ class TraitReference
     return item_refs;
   }
 
+  void get_trait_items_and_supers (
+    std::vector<const TraitItemReference *> &result) const
+  {
+    for (const auto &item : item_refs)
+      result.push_back (&item);
+
+    for (const auto &super_trait : super_traits)
+      super_trait->get_trait_items_and_supers (result);
+  }
+
   void on_resolved ()
   {
     for (auto &item : item_refs)
@@ -451,6 +461,20 @@ class TraitReference
     return trait_substs;
   }
 
+  bool satisfies_bound (const TraitReference &reference) const
+  {
+    if (is_equal (reference))
+      return true;
+
+    for (const auto &super_trait : super_traits)
+      {
+	if (super_trait->satisfies_bound (reference))
+	  return true;
+      }
+
+    return false;
+  }
+
 private:
   const HIR::Trait *hir_trait_ref;
   std::vector<TraitItemReference> item_refs;

gcc/rust/typecheck/rust-tyty.cc

@@ -136,22 +136,18 @@ bool
 BaseType::satisfies_bound (const TypeBoundPredicate &predicate) const
 {
   const Resolver::TraitReference *query = predicate.get ();
-  for (auto &bound : specified_bounds)
+  for (const auto &bound : specified_bounds)
     {
       const Resolver::TraitReference *item = bound.get ();
-      bool found = item->get_mappings ().get_defid ()
-		   == query->get_mappings ().get_defid ();
-      if (found)
+      if (item->satisfies_bound (*query))
 	return true;
     }
 
   auto probed = Resolver::TypeBoundsProbe::Probe (this);
-  for (auto &b : probed)
+  for (const auto &b : probed)
     {
       const Resolver::TraitReference *bound = b.first;
-      bool found = bound->get_mappings ().get_defid ()
-		   == query->get_mappings ().get_defid ();
-      if (found)
+      if (bound->satisfies_bound (*query))
 	return true;
     }
 
@@ -191,7 +187,6 @@ BaseType::bounds_compatible (const BaseType &other, Location locus,
 	  rust_error_at (r,
 			 "bounds not satisfied for %s %<%s%> is not satisfied",
 			 other.get_name ().c_str (), missing_preds.c_str ());
-	  // rust_assert (!emit_error);
 	}
     }
 
@@ -2956,23 +2951,15 @@ DynamicObjectType::get_object_items () const
   for (auto &bound : get_specified_bounds ())
     {
       const Resolver::TraitReference *trait = bound.get ();
-      for (auto &item : trait->get_trait_items ())
-	{
-	  if (item.get_trait_item_type ()
-		== Resolver::TraitItemReference::TraitItemType::FN
-	      && item.is_object_safe ())
-	    items.push_back ({&item, &bound});
-	}
+      std::vector<const Resolver::TraitItemReference *> trait_items;
+      trait->get_trait_items_and_supers (trait_items);
 
-      for (auto &super_trait : trait->get_super_traits ())
+      for (auto &item : trait_items)
 	{
-	  for (auto &item : super_trait->get_trait_items ())
-	    {
-	      if (item.get_trait_item_type ()
-		    == Resolver::TraitItemReference::TraitItemType::FN
-		  && item.is_object_safe ())
-		items.push_back ({&item, &bound});
-	    }
+	  if (item->get_trait_item_type ()
+		== Resolver::TraitItemReference::TraitItemType::FN
+	      && item->is_object_safe ())
+	    items.push_back ({item, &bound});
 	}
     }
   return items;