Use tl::expected in the parser to avoid error state

gcc/rust/ast/rust-ast.cc

@@ -3478,7 +3478,9 @@ Module::load_items ()
 
   // we need to parse any possible inner attributes for this module
   inner_attrs = parser.parse_inner_attributes ();
-  auto parsed_items = parser.parse_items ();
+  auto parsed_items = parser.parse_items ().value_or (
+    std::vector<std::unique_ptr<AST::Item>>{});
+
   for (const auto &error : parser.get_errors ())
     error.emit ();
 
@@ -3693,8 +3695,8 @@ AttributeParser::is_end_meta_item_tok (TokenId id) const
 std::unique_ptr<MetaItem>
 AttributeParser::parse_path_meta_item ()
 {
-  SimplePath path = parser->parse_simple_path ();
-  if (path.is_empty ())
+  auto path = parser->parse_simple_path ();
+  if (!path)
     {
       rust_error_at (lexer->peek_token ()->get_locus (),
 		     "failed to parse simple path in attribute");
@@ -3709,7 +3711,7 @@ AttributeParser::parse_path_meta_item ()
 	  = parse_meta_item_seq ();
 
 	return std::unique_ptr<MetaItemSeq> (
-	  new MetaItemSeq (std::move (path), std::move (meta_items)));
+	  new MetaItemSeq (std::move (path.value ()), std::move (meta_items)));
       }
     case EQUAL:
       {
@@ -3723,12 +3725,12 @@ AttributeParser::parse_path_meta_item ()
 	  return nullptr;
 
 	return std::unique_ptr<MetaItemPathExpr> (
-	  new MetaItemPathExpr (std::move (path), std::move (expr)));
+	  new MetaItemPathExpr (std::move (path.value ()), std::move (expr)));
       }
     case COMMA:
       // just simple path
       return std::unique_ptr<MetaItemPath> (
-	new MetaItemPath (std::move (path)));
+	new MetaItemPath (std::move (path.value ())));
     default:
       rust_error_at (lexer->peek_token ()->get_locus (),
 		     "unrecognised token '%s' in meta item",

gcc/rust/ast/rust-ast.h

@@ -477,38 +477,21 @@ struct Visibility
   SimplePath in_path;
   location_t locus;
 
-  // should this store location info?
-
-public:
-  // Creates a Visibility - TODO make constructor protected or private?
   Visibility (VisType vis_type, SimplePath in_path, location_t locus)
     : vis_type (vis_type), in_path (std::move (in_path)), locus (locus)
   {}
 
+public:
   VisType get_vis_type () const { return vis_type; }
 
-  // Returns whether visibility is in an error state.
-  bool is_error () const
-  {
-    return vis_type == PUB_IN_PATH && in_path.is_empty ();
-  }
-
   // Returns whether a visibility has a path
-  bool has_path () const { return !is_error () && vis_type >= PUB_CRATE; }
+  bool has_path () const { return vis_type >= PUB_CRATE; }
 
   // Returns whether visibility is public or not.
-  bool is_public () const { return vis_type != PRIV && !is_error (); }
+  bool is_public () const { return vis_type != PRIV; }
 
   location_t get_locus () const { return locus; }
 
-  // empty?
-  // Creates an error visibility.
-  static Visibility create_error ()
-  {
-    return Visibility (PUB_IN_PATH, SimplePath::create_empty (),
-		       UNDEF_LOCATION);
-  }
-
   // Unique pointer custom clone function
   /*std::unique_ptr<Visibility> clone_visibility() const {
       return std::unique_ptr<Visibility>(clone_visibility_impl());

gcc/rust/ast/rust-item.h

@@ -814,7 +814,7 @@ class Module : public VisItem
   // Loaded module constructor, with items
   Module (Identifier name, location_t locus,
 	  std::vector<std::unique_ptr<Item>> items,
-	  Visibility visibility = Visibility::create_error (),
+	  Visibility visibility = Visibility::create_private (),
 	  Unsafety safety = Unsafety::Normal,
 	  std::vector<Attribute> inner_attrs = std::vector<Attribute> (),
 	  std::vector<Attribute> outer_attrs = std::vector<Attribute> ())
@@ -1743,7 +1743,7 @@ class StructField
   bool has_outer_attributes () const { return !outer_attrs.empty (); }
 
   // Returns whether struct field has a non-private (non-default) visibility.
-  bool has_visibility () const { return !visibility.is_error (); }
+  bool has_visibility () const { return true; }
 
   StructField (Identifier field_name, std::unique_ptr<Type> field_type,
 	       Visibility vis, location_t locus,
@@ -1797,8 +1797,8 @@ class StructField
   // Creates an error state struct field.
   static StructField create_error ()
   {
-    return StructField (std::string (""), nullptr, Visibility::create_error (),
-			UNDEF_LOCATION);
+    return StructField (std::string (""), nullptr,
+			Visibility::create_private (), UNDEF_LOCATION);
   }
 
   std::string as_string () const;
@@ -1902,7 +1902,7 @@ class TupleField
 
   /* Returns whether tuple field has a non-default visibility (i.e. a public
    * one) */
-  bool has_visibility () const { return !visibility.is_error (); }
+  bool has_visibility () const { return true; }
 
   // Complete constructor
   TupleField (std::unique_ptr<Type> field_type, Visibility vis,
@@ -1952,7 +1952,7 @@ class TupleField
   // Creates an error state tuple field.
   static TupleField create_error ()
   {
-    return TupleField (nullptr, Visibility::create_error (), UNDEF_LOCATION);
+    return TupleField (nullptr, Visibility::create_private (), UNDEF_LOCATION);
   }
 
   std::string as_string () const;
@@ -3368,7 +3368,7 @@ class ExternalTypeItem : public ExternalItem
   bool has_outer_attrs () const { return !outer_attrs.empty (); }
 
   // Returns whether item has non-default visibility.
-  bool has_visibility () const { return !visibility.is_error (); }
+  bool has_visibility () const { return true; }
 
   location_t get_locus () const { return locus; }
 
@@ -3460,7 +3460,7 @@ class ExternalStaticItem : public ExternalItem
   bool has_outer_attrs () const { return !outer_attrs.empty (); }
 
   // Returns whether item has non-default visibility.
-  bool has_visibility () const { return !visibility.is_error (); }
+  bool has_visibility () const { return true; }
 
   location_t get_locus () const { return locus; }
 

gcc/rust/ast/rust-macro.h

@@ -529,7 +529,7 @@ class MacroRulesDefinition : public VisItem
     return std::make_unique<MacroRulesDefinition> (
       MacroRulesDefinition (rule_name, delim_type, rules, outer_attrs, locus,
 			    AST::MacroRulesDefinition::MacroKind::MBE,
-			    AST::Visibility::create_error ()));
+			    AST::Visibility::create_private ()));
   }
 
   static std::unique_ptr<MacroRulesDefinition>

gcc/rust/expand/rust-macro-builtins-include.cc

@@ -248,7 +248,8 @@ MacroBuiltin::include_handler (location_t invoc_locus,
   std::vector<std::unique_ptr<AST::Item>> parsed_items{};
 
   if (is_semicoloned)
-    parsed_items = parser.parse_items ();
+    parsed_items = parser.parse_items ().value_or (
+      std::vector<std::unique_ptr<AST::Item>>{});
   else
     parsed_expr = parser.parse_expr ();
 

gcc/rust/expand/rust-macro-builtins-offset-of.cc

@@ -56,7 +56,7 @@ MacroBuiltin::offset_of_handler (location_t invoc_locus,
   parser.skip_token (COMMA);
 
   auto field_tok = parser.parse_identifier_or_keyword_token ();
-  auto invalid_field = !field_tok || !field_tok->should_have_str ();
+  auto invalid_field = !field_tok || !field_tok.value ()->should_have_str ();
 
   if (invalid_field)
     rust_error_at (invoc_locus, "could not parse field argument for %qs",
@@ -65,7 +65,7 @@ MacroBuiltin::offset_of_handler (location_t invoc_locus,
   if (!type || invalid_field)
     return tl::nullopt;
 
-  auto field = Identifier (field_tok->get_str ());
+  auto field = Identifier (field_tok.value ()->get_str ());
 
   // FIXME: Do we need to do anything to handle the optional comma at the end?
   parser.maybe_skip_token (COMMA);

gcc/rust/expand/rust-macro-expand.cc

@@ -858,7 +858,9 @@ transcribe_many_items (Parser<MacroInvocLexer> &parser, TokenId &delimiter)
 {
   return parse_many (parser, delimiter, [&parser] () {
     auto item = parser.parse_item (true);
-    return AST::SingleASTNode (std::move (item));
+    if (!item)
+      return AST::SingleASTNode (std::unique_ptr<AST::Item> (nullptr));
+    return AST::SingleASTNode (std::move (item.value ()));
   });
 }
 
@@ -1188,9 +1190,9 @@ MacroExpander::parse_proc_macro_output (ProcMacro::TokenStream ts)
       while (lex.peek_token ()->get_id () != END_OF_FILE)
 	{
 	  auto result = parser.parse_item (false);
-	  if (result == nullptr)
+	  if (!result)
 	    break;
-	  nodes.emplace_back (std::move (result));
+	  nodes.emplace_back (std::move (result.value ()));
 	}
       break;
     case ContextType::STMT:

gcc/rust/hir/rust-ast-lower.cc

@@ -38,8 +38,6 @@ translate_visibility (const AST::Visibility &vis)
   // the AST vis is an error?
   // FIXME: We need to add a `create_private()` static function to the
   // AST::Visibility class and use it when the vis is empty in the parser...
-  if (vis.is_error ())
-    return Visibility::create_error ();
 
   switch (vis.get_vis_type ())
     {
@@ -57,7 +55,7 @@ translate_visibility (const AST::Visibility &vis)
       break;
     }
 
-  return Visibility::create_error ();
+  rust_unreachable ();
 }
 
 ASTLowering::ASTLowering (AST::Crate &astCrate) : astCrate (astCrate) {}