Unify cloning of associated items

gcc/rust/ChangeLog:

	* ast/rust-ast.h
	(class AssociatedItem):
	New class with virtual cloning function and virtual destructor.
	(class TraitItem):
	Inherit from AssociatedItem, rename cloning function to match,
	remove virtual destructor.
	(class InherentImplItem): Likewise.
	(class TraitImplItem): Likewise.
	* ast/rust-item.h
	(class Method): Update cloning functions.
	(class Function): Likewise.
	(class TypeAlias): Likewise.
	(class ConstantItem): Likewise.
	(class TraitItemFunc): Likewise.
	(class TraitItemMethod): Likewise.
	(class TraitItemConst): Likewise.
	(class TraitItemType): Likewise.
	* ast/rust-macro.h
	(class MacroInvocation): Likewise.

gcc/rust/ast/rust-ast.h

@@ -1446,27 +1446,35 @@ class LifetimeParam : public GenericParam
   }
 };
 
+class AssociatedItem : public Visitable
+{
+protected:
+  // Clone function implementation as pure virtual method
+  virtual AssociatedItem *clone_associated_item_impl () const = 0;
+
+public:
+  virtual ~AssociatedItem () {}
+};
+
 // Item used in trait declarations - abstract base class
-class TraitItem : public Visitable
+class TraitItem : virtual public AssociatedItem
 {
 protected:
   TraitItem (location_t locus)
     : node_id (Analysis::Mappings::get ()->get_next_node_id ()), locus (locus)
   {}
 
   // Clone function implementation as pure virtual method
-  virtual TraitItem *clone_trait_item_impl () const = 0;
+  virtual TraitItem *clone_associated_item_impl () const override = 0;
 
   NodeId node_id;
   location_t locus;
 
 public:
-  virtual ~TraitItem () {}
-
   // Unique pointer custom clone function
   std::unique_ptr<TraitItem> clone_trait_item () const
   {
-    return std::unique_ptr<TraitItem> (clone_trait_item_impl ());
+    return std::unique_ptr<TraitItem> (clone_associated_item_impl ());
   }
 
   virtual std::string as_string () const = 0;
@@ -1480,19 +1488,17 @@ class TraitItem : public Visitable
 
 /* Abstract base class for items used within an inherent impl block (the impl
  * name {} one) */
-class InherentImplItem : public Visitable
+class InherentImplItem : virtual public AssociatedItem
 {
 protected:
   // Clone function implementation as pure virtual method
-  virtual InherentImplItem *clone_inherent_impl_item_impl () const = 0;
+  virtual InherentImplItem *clone_associated_item_impl () const override = 0;
 
 public:
-  virtual ~InherentImplItem () {}
-
   // Unique pointer custom clone function
   std::unique_ptr<InherentImplItem> clone_inherent_impl_item () const
   {
-    return std::unique_ptr<InherentImplItem> (clone_inherent_impl_item_impl ());
+    return std::unique_ptr<InherentImplItem> (clone_associated_item_impl ());
   }
 
   virtual std::string as_string () const = 0;
@@ -1504,18 +1510,16 @@ class InherentImplItem : public Visitable
 };
 
 // Abstract base class for items used in a trait impl
-class TraitImplItem : public Visitable
+class TraitImplItem : virtual public AssociatedItem
 {
 protected:
-  virtual TraitImplItem *clone_trait_impl_item_impl () const = 0;
+  virtual TraitImplItem *clone_associated_item_impl () const override = 0;
 
 public:
-  virtual ~TraitImplItem (){};
-
   // Unique pointer custom clone function
   std::unique_ptr<TraitImplItem> clone_trait_impl_item () const
   {
-    return std::unique_ptr<TraitImplItem> (clone_trait_impl_item_impl ());
+    return std::unique_ptr<TraitImplItem> (clone_associated_item_impl ());
   }
 
   virtual std::string as_string () const = 0;

gcc/rust/ast/rust-item.h

@@ -923,14 +923,7 @@ class Method : public InherentImplItem, public TraitImplItem
 protected:
   /* Use covariance to implement clone function as returning this object
    * rather than base */
-  Method *clone_inherent_impl_item_impl () const final override
-  {
-    return clone_method_impl ();
-  }
-
-  /* Use covariance to implement clone function as returning this object
-   * rather than base */
-  Method *clone_trait_impl_item_impl () const final override
+  Method *clone_associated_item_impl () const final override
   {
     return clone_method_impl ();
   }
@@ -1703,14 +1696,7 @@ class Function : public VisItem, public InherentImplItem, public TraitImplItem
 
   /* Use covariance to implement clone function as returning this object
    * rather than base */
-  Function *clone_inherent_impl_item_impl () const override
-  {
-    return new Function (*this);
-  }
-
-  /* Use covariance to implement clone function as returning this object
-   * rather than base */
-  Function *clone_trait_impl_item_impl () const override
+  Function *clone_associated_item_impl () const override
   {
     return new Function (*this);
   }
@@ -1834,7 +1820,7 @@ class TypeAlias : public VisItem, public TraitImplItem
 
   /* Use covariance to implement clone function as returning this object
    * rather than base */
-  TypeAlias *clone_trait_impl_item_impl () const override
+  TypeAlias *clone_associated_item_impl () const override
   {
     return new TypeAlias (*this);
   }
@@ -2699,14 +2685,7 @@ class ConstantItem : public VisItem,
 
   /* Use covariance to implement clone function as returning this object
    * rather than base */
-  ConstantItem *clone_inherent_impl_item_impl () const override
-  {
-    return new ConstantItem (*this);
-  }
-
-  /* Use covariance to implement clone function as returning this object
-   * rather than base */
-  ConstantItem *clone_trait_impl_item_impl () const override
+  ConstantItem *clone_associated_item_impl () const override
   {
     return new ConstantItem (*this);
   }
@@ -3016,7 +2995,7 @@ class TraitItemFunc : public TraitItem
 
 protected:
   // Clone function implementation as (not pure) virtual method
-  TraitItemFunc *clone_trait_item_impl () const override
+  TraitItemFunc *clone_associated_item_impl () const override
   {
     return new TraitItemFunc (*this);
   }
@@ -3232,7 +3211,7 @@ class TraitItemMethod : public TraitItem
 
 protected:
   // Clone function implementation as (not pure) virtual method
-  TraitItemMethod *clone_trait_item_impl () const override
+  TraitItemMethod *clone_associated_item_impl () const override
   {
     return new TraitItemMethod (*this);
   }
@@ -3337,7 +3316,7 @@ class TraitItemConst : public TraitItem
 
 protected:
   // Clone function implementation as (not pure) virtual method
-  TraitItemConst *clone_trait_item_impl () const override
+  TraitItemConst *clone_associated_item_impl () const override
   {
     return new TraitItemConst (*this);
   }
@@ -3424,7 +3403,7 @@ class TraitItemType : public TraitItem
 
 protected:
   // Clone function implementation as (not pure) virtual method
-  TraitItemType *clone_trait_item_impl () const override
+  TraitItemType *clone_associated_item_impl () const override
   {
     return new TraitItemType (*this);
   }

gcc/rust/ast/rust-macro.h

@@ -803,20 +803,10 @@ class MacroInvocation : public TypeNoBounds,
 
   bool is_item () const override { return !has_semicolon (); }
 
-  TraitItem *clone_trait_item_impl () const override
+  MacroInvocation *clone_associated_item_impl () const override
   {
     return clone_macro_invocation_impl ();
   };
-
-  TraitImplItem *clone_trait_impl_item_impl () const override
-  {
-    return clone_macro_invocation_impl ();
-  };
-
-  InherentImplItem *clone_inherent_impl_item_impl () const override
-  {
-    return clone_macro_invocation_impl ();
-  }
 };
 
 // more generic meta item path-only form