gccrs: Fix bug with bad type bindings not looking at super traits

When resolving type bounds, we need to examine super traits to properly
determine if type bindings are valid in the current context.

gcc/rust/ChangeLog:

	* typecheck/rust-tyty-bounds.cc: Check super traits for type bindings.
	* typecheck/rust-tyty.h: Add helper methods for bound checking.

Author: philberty

gcc/rust/typecheck/rust-tyty-bounds.cc

@@ -754,16 +754,34 @@ size_t
 TypeBoundPredicate::get_num_associated_bindings () const
 {
   size_t count = 0;
+
+  get_trait_hierachy ([&count] (const Resolver::TraitReference &ref) {
+    for (const auto &trait_item : ref.get_trait_items ())
+      {
+	bool is_associated_type
+	  = trait_item.get_trait_item_type ()
+	    == Resolver::TraitItemReference::TraitItemType::TYPE;
+	if (is_associated_type)
+	  count++;
+      }
+  });
+
+  return count;
+}
+
+void
+TypeBoundPredicate::get_trait_hierachy (
+  std::function<void (const Resolver::TraitReference &)> callback) const
+{
   auto trait_ref = get ();
-  for (const auto &trait_item : trait_ref->get_trait_items ())
+  callback (*trait_ref);
+
+  for (auto &super : super_traits)
     {
-      bool is_associated_type
-	= trait_item.get_trait_item_type ()
-	  == Resolver::TraitItemReference::TraitItemType::TYPE;
-      if (is_associated_type)
-	count++;
+      const auto &super_trait_ref = *super.get ();
+      callback (super_trait_ref);
+      super.get_trait_hierachy (callback);
     }
-  return count;
 }
 
 TypeBoundPredicateItem

gcc/rust/typecheck/rust-tyty.h

@@ -593,6 +593,9 @@ class TypeBoundPredicate : public SubstitutionRef
 
   TypeBoundPredicate (mark_is_error);
 
+  void get_trait_hierachy (
+    std::function<void (const Resolver::TraitReference &)> callback) const;
+
   DefId reference;
   location_t locus;
   bool error_flag;