Parse named variadic parameters

Add ability to parse named variadic parameters in extern c functions.

gcc/rust/ChangeLog:

	* parse/rust-parse-impl.h (Parser::parse_named_function_param): Add
	new parsing ability.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

gcc/rust/parse/rust-parse-impl.h

@@ -5960,7 +5960,7 @@ Parser<ManagedTokenSource>::parse_named_function_param ()
   AST::AttrVec outer_attrs = parse_outer_attributes ();
   location_t locus = lexer.peek_token ()->get_locus ();
 
-  if (lexer.peek_token ()->get_id () == ELLIPSIS)
+  if (lexer.peek_token ()->get_id () == ELLIPSIS) // Unnamed variadic
     {
       lexer.skip_token (); // Skip ellipsis
       return AST::NamedFunctionParam (std::move (outer_attrs), locus);
@@ -5992,6 +5992,13 @@ Parser<ManagedTokenSource>::parse_named_function_param ()
       return AST::NamedFunctionParam::create_error ();
     }
 
+  if (lexer.peek_token ()->get_id () == ELLIPSIS) // Named variadic
+    {
+      lexer.skip_token (); // Skip ellipsis
+      return AST::NamedFunctionParam (std::move (name), std::move (outer_attrs),
+				      locus);
+    }
+
   // parse (required) type
   std::unique_ptr<AST::Type> param_type = parse_type ();
   if (param_type == nullptr)