Make TypeBoundPredicate a subclass of the SubstitutionRef

This will allow us to reuse our generic substitions code to manage generic
traits and their substitions better. It will unify the handling in one
path so we get the same error handling.

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

@@ -407,7 +407,7 @@ public:
 
   bool trait_has_generics () const { return !trait_substs.empty (); }
 
-  const std::vector<TyTy::SubstitutionParamMapping> &get_trait_substs () const
+  std::vector<TyTy::SubstitutionParamMapping> get_trait_substs () const
   {
     return trait_substs;
   }

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

@@ -150,8 +150,13 @@ private:
 
     // They also inherit themselves as a bound this enables a trait item to
     // reference other Self::trait_items
+    std::vector<TyTy::SubstitutionParamMapping> self_subst_copy;
+    for (auto &sub : substitutions)
+      self_subst_copy.push_back (sub.clone ());
+
     specified_bounds.push_back (
       TyTy::TypeBoundPredicate (trait_reference->get_mappings ().get_defid (),
+				std::move (self_subst_copy),
 				trait_reference->get_locus ()));
 
     std::vector<const TraitReference *> super_traits;
@@ -168,8 +173,8 @@ private:
 		// FIXME this might be recursive we need a check for that
 
 		TraitReference *trait = resolve_trait_path (b->get_path ());
-		TyTy::TypeBoundPredicate predicate (
-		  trait->get_mappings ().get_defid (), bound->get_locus ());
+		TyTy::TypeBoundPredicate predicate (*trait,
+						    bound->get_locus ());
 
 		specified_bounds.push_back (std::move (predicate));
 		super_traits.push_back (predicate.get ());

gcc/rust/typecheck/rust-hir-type-check-item.h

@@ -79,8 +79,8 @@ public:
 	rust_assert (!trait_reference->is_error ());
 
 	// setup the bound
-	TyTy::TypeBoundPredicate predicate (
-	  trait_reference->get_mappings ().get_defid (), ref->get_locus ());
+	TyTy::TypeBoundPredicate predicate (*trait_reference,
+					    ref->get_locus ());
 	auto &final_seg = ref->get_final_segment ();
 	if (final_seg->is_generic_segment ())
 	  {

gcc/rust/typecheck/rust-hir-type-check-type.cc

@@ -550,8 +550,7 @@ TypeCheckType::visit (HIR::TraitObjectType &type)
 
       auto &type_path = trait_bound.get_path ();
       TraitReference *trait = resolve_trait_path (type_path);
-      TyTy::TypeBoundPredicate predicate (trait->get_mappings ().get_defid (),
-					  trait_bound.get_locus ());
+      TyTy::TypeBoundPredicate predicate (*trait, trait_bound.get_locus ());
       auto &final_seg = type_path.get_final_segment ();
       if (final_seg->is_generic_segment ())
 	{

gcc/rust/typecheck/rust-hir-type-check-type.h

@@ -247,8 +247,7 @@ public:
 
 		  auto &type_path = b->get_path ();
 		  TraitReference *trait = resolve_trait_path (type_path);
-		  TyTy::TypeBoundPredicate predicate (
-		    trait->get_mappings ().get_defid (), b->get_locus ());
+		  TyTy::TypeBoundPredicate predicate (*trait, b->get_locus ());
 
 		  auto &final_seg = type_path.get_final_segment ();
 		  if (final_seg->is_generic_segment ())
@@ -318,8 +317,7 @@ public:
 
 	      auto &type_path = b->get_path ();
 	      TraitReference *trait = resolve_trait_path (type_path);
-	      TyTy::TypeBoundPredicate predicate (
-		trait->get_mappings ().get_defid (), b->get_locus ());
+	      TyTy::TypeBoundPredicate predicate (*trait, b->get_locus ());
 
 	      auto &final_seg = type_path.get_final_segment ();
 	      if (final_seg->is_generic_segment ())

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

@@ -67,17 +67,38 @@ TypeCheckBase::resolve_trait_path (HIR::TypePath &path)
 
 namespace TyTy {
 
-TypeBoundPredicate::TypeBoundPredicate (DefId reference, Location locus)
-  : reference (reference), locus (locus), args (nullptr)
+TypeBoundPredicate::TypeBoundPredicate (
+  const Resolver::TraitReference &trait_reference, Location locus)
+  : SubstitutionRef (trait_reference.get_trait_substs (),
+		     SubstitutionArgumentMappings::error ()),
+    reference (trait_reference.get_mappings ().get_defid ()), locus (locus),
+    args (nullptr), error_flag (false)
 {}
 
+TypeBoundPredicate::TypeBoundPredicate (
+  DefId reference, std::vector<SubstitutionParamMapping> substitutions,
+  Location locus)
+  : SubstitutionRef (std::move (substitutions),
+		     SubstitutionArgumentMappings::error ()),
+    reference (reference), locus (locus), args (nullptr), error_flag (false)
+{}
+
+TypeBoundPredicate::TypeBoundPredicate (const TypeBoundPredicate &other)
+  : SubstitutionRef ({}, other.used_arguments), reference (other.reference),
+    locus (other.locus), args (other.args), error_flag (other.error_flag)
+{
+  substitutions.clear ();
+  if (!other.is_error ())
+    {
+      for (const auto &p : other.get_substs ())
+	substitutions.push_back (p.clone ());
+    }
+}
+
 std::string
 TypeBoundPredicate::as_string () const
 {
-  return get ()->as_string ()
-	 + (has_generic_args ()
-	      ? std::string ("<") + args->as_string () + std::string (">")
-	      : "");
+  return get ()->as_string () + subst_as_string ();
 }
 
 const Resolver::TraitReference *
@@ -183,6 +204,25 @@ TypeBoundPredicateItem::get_tyty_for_receiver (
 
   return resolved;
 }
+bool
+TypeBoundPredicate::is_error () const
+{
+  auto context = Resolver::TypeCheckContext::get ();
+
+  Resolver::TraitReference *ref = nullptr;
+  bool ok = context->lookup_trait_reference (reference, &ref);
+
+  return !ok || error_flag;
+}
+
+BaseType *
+TypeBoundPredicate::handle_substitions (SubstitutionArgumentMappings mappings)
+{
+  gcc_unreachable ();
+  return nullptr;
+}
+
+// trait item reference
 
 const Resolver::TraitItemReference *
 TypeBoundPredicateItem::get_raw_item () const

gcc/rust/typecheck/rust-tyty.h

@@ -939,10 +939,17 @@ protected:
   SubstitutionArgumentMappings used_arguments;
 };
 
-class TypeBoundPredicate
+class TypeBoundPredicate : public SubstitutionRef
 {
 public:
-  TypeBoundPredicate (DefId reference, Location locus);
+  TypeBoundPredicate (const Resolver::TraitReference &trait_reference,
+		      Location locus);
+
+  TypeBoundPredicate (DefId reference,
+		      std::vector<SubstitutionParamMapping> substitutions,
+		      Location locus);
+
+  TypeBoundPredicate (const TypeBoundPredicate &other);
 
   std::string as_string () const;
 
@@ -975,10 +982,17 @@ public:
     return args->has_generic_args ();
   }
 
+  // WARNING THIS WILL ALWAYS RETURN NULLPTR
+  BaseType *
+  handle_substitions (SubstitutionArgumentMappings mappings) override final;
+
+  bool is_error () const;
+
 private:
   DefId reference;
   Location locus;
   HIR::GenericArgs *args;
+  bool error_flag;
 };
 
 // https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.VariantDef.html