[ObjC*] Add @required/@optional to methods in protocol lists.

Index: gcc/c-parser.c
===================================================================
--- gcc/c-parser.c	(revision 164748)
+++ gcc/c-parser.c	(working copy)
@@ -6743,6 +6743,8 @@  c_parser_objc_method_definition (c_parser *parser)
      objc-methodprotolist objc-methodproto
      objc-methodprotolist declaration
      objc-methodprotolist ;
+     @optional
+     @required
 
    The declaration is a data definition, which may be missing
    declaration specifiers under the same rules and diagnostics as
@@ -6775,7 +6777,18 @@  c_parser_objc_methodprotolist (c_parser *parser)
 	default:
 	  if (c_parser_next_token_is_keyword (parser, RID_AT_END))
 	    return;
-	  c_parser_declaration_or_fndef (parser, false, false, true,
+	  else if (c_parser_next_token_is_keyword (parser, RID_AT_OPTIONAL))
+	    {
+	      objc_set_method_opt (true);
+	      c_parser_consume_token (parser);
+	    }
+	  else if (c_parser_next_token_is_keyword (parser, RID_AT_REQUIRED))
+	    {
+	      objc_set_method_opt (false);
+	      c_parser_consume_token (parser);
+	    }
+	  else
+	    c_parser_declaration_or_fndef (parser, false, false, true,
 					 false, true);
 	  break;
 	}
Index: gcc/c-family/c-common.c
===================================================================
--- gcc/c-family/c-common.c	(revision 164748)
+++ gcc/c-family/c-common.c	(working copy)
@@ -541,6 +541,8 @@  const struct c_common_resword c_common_reswords[]
   { "selector",		RID_AT_SELECTOR,	D_OBJC },
   { "finally",		RID_AT_FINALLY,		D_OBJC },
   { "synchronized",	RID_AT_SYNCHRONIZED,	D_OBJC },
+  { "optional",		RID_AT_OPTIONAL,	D_OBJC },
+  { "required",		RID_AT_REQUIRED,	D_OBJC },
   /* These are recognized only in protocol-qualifier context
      (see above) */
   { "bycopy",		RID_BYCOPY,		D_OBJC },
Index: gcc/c-family/c-common.h
===================================================================
--- gcc/c-family/c-common.h	(revision 164748)
+++ gcc/c-family/c-common.h	(working copy)
@@ -142,7 +142,8 @@  enum rid
   RID_AT_PRIVATE,  RID_AT_PROTECTED, RID_AT_PUBLIC,
   RID_AT_PROTOCOL, RID_AT_SELECTOR,
   RID_AT_THROW,	   RID_AT_TRY,       RID_AT_CATCH,
-  RID_AT_FINALLY,  RID_AT_SYNCHRONIZED,
+  RID_AT_FINALLY,  RID_AT_SYNCHRONIZED, 
+  RID_AT_OPTIONAL, RID_AT_REQUIRED,
   RID_AT_INTERFACE,
   RID_AT_IMPLEMENTATION,
 
@@ -1007,6 +1008,7 @@  extern tree objc_build_synchronized (location_t, t
 extern int objc_static_init_needed_p (void);
 extern tree objc_generate_static_init_call (tree);
 extern tree objc_generate_write_barrier (tree, enum tree_code, tree);
+extern void objc_set_method_opt (bool);
 
 /* The following are provided by the C and C++ front-ends, and called by
    ObjC/ObjC++.  */
Index: gcc/c-family/stub-objc.c
===================================================================
--- gcc/c-family/stub-objc.c	(revision 164748)
+++ gcc/c-family/stub-objc.c	(working copy)
@@ -126,6 +126,11 @@  objc_start_protocol (tree ARG_UNUSED (proto),
 {
 }
 
+void 
+objc_set_method_opt (bool ARG_UNUSED (optional))
+{
+}
+
 void
 objc_start_class_interface (tree ARG_UNUSED (name),
 			    tree ARG_UNUSED (super),
Index: gcc/objc/objc-act.c
===================================================================
--- gcc/objc/objc-act.c	(revision 164748)
+++ gcc/objc/objc-act.c	(working copy)
@@ -146,7 +146,7 @@  static void objc_start_function (tree, tree, tree,
 #endif
 static tree start_protocol (enum tree_code, tree, tree);
 static tree build_method_decl (enum tree_code, tree, tree, tree, bool);
-static tree objc_add_method (tree, tree, int);
+static tree objc_add_method (tree, tree, int, bool);
 static tree add_instance_variable (tree, int, tree);
 static tree build_ivar_reference (tree);
 static tree is_ivar (tree, tree);
@@ -352,6 +352,10 @@  int objc_public_flag;
 /* Use to generate method labels.  */
 static int method_slot = 0;
 
+/* Flag to say wether methods in a protocol are optional or
+   required.  */
+static bool objc_method_optional_flag = false;
+
 static int objc_collecting_ivars = 0;
 
 #define BUFSIZE		1024
@@ -687,6 +691,7 @@  objc_start_protocol (tree name, tree protos, tree
 		" of the compiler, (ignored)");
   objc_interface_context
     = start_protocol (PROTOCOL_INTERFACE_TYPE, name, protos);
+  objc_method_optional_flag = false;
 }
 
 void
@@ -701,6 +706,7 @@  objc_finish_interface (void)
 {
   finish_class (objc_interface_context);
   objc_interface_context = NULL_TREE;
+  objc_method_optional_flag = false;
 }
 
 void
@@ -753,6 +759,18 @@  objc_set_visibility (int visibility)
 }
 
 void
+objc_set_method_opt (bool optional)
+{
+  objc_method_optional_flag = optional;
+  if (!objc_interface_context 
+      || TREE_CODE (objc_interface_context) != PROTOCOL_INTERFACE_TYPE)
+    {
+      error ("@optional/@required is allowed in @protocol context only.");
+      objc_method_optional_flag = false;
+    }
+}
+
+void
 objc_set_method_type (enum tree_code type)
 {
   objc_inherit_code = (type == PLUS_EXPR
@@ -787,7 +805,8 @@  objc_add_method_declaration (tree decl, tree attri
 
   objc_add_method (objc_interface_context,
 		   decl,
-		   objc_inherit_code == CLASS_METHOD_DECL);
+		   objc_inherit_code == CLASS_METHOD_DECL,
+		   objc_method_optional_flag);
 }
 
 /* Return 'true' if the method definition could be started, and
@@ -816,7 +835,8 @@  objc_start_method_definition (tree decl, tree attr
 
   objc_add_method (objc_implementation_context,
 		   decl,
-		   objc_inherit_code == CLASS_METHOD_DECL);
+		   objc_inherit_code == CLASS_METHOD_DECL, 
+		   /* is optional */ false);
   start_method_def (decl);
   return true;
 }
@@ -7073,11 +7093,32 @@  add_method_to_hash_list (hash *hash_list, tree met
 }
 
 static tree
-objc_add_method (tree klass, tree method, int is_class)
+objc_add_method (tree klass, tree method, int is_class, bool is_optional)
 {
   tree mth;
 
-  if (!(mth = lookup_method (is_class
+  /* @optional methods are added to protocol's OPTIONAL list */
+  if (is_optional)
+    {
+      gcc_assert (TREE_CODE (klass) == PROTOCOL_INTERFACE_TYPE);
+      if (!(mth = lookup_method (is_class
+				? PROTOCOL_OPTIONAL_CLS_METHODS (klass)
+				: PROTOCOL_OPTIONAL_NST_METHODS (klass), 
+								method)))
+	{
+	  if (is_class)
+	    {
+	      TREE_CHAIN (method) = PROTOCOL_OPTIONAL_CLS_METHODS (klass);
+	      PROTOCOL_OPTIONAL_CLS_METHODS (klass) = method;
+	    }
+	  else
+	    {
+	      TREE_CHAIN (method) = PROTOCOL_OPTIONAL_NST_METHODS (klass);
+	      PROTOCOL_OPTIONAL_NST_METHODS (klass) = method;
+	    }
+	}
+    }
+  else if (!(mth = lookup_method (is_class
 			     ? CLASS_CLS_METHODS (klass)
 			     : CLASS_NST_METHODS (klass), method)))
     {
@@ -9064,7 +9105,8 @@  really_start_method (tree method,
 
 	  if (interface)
 	    objc_add_method (interface, copy_node (method),
-			     TREE_CODE (method) == CLASS_METHOD_DECL);
+			     TREE_CODE (method) == CLASS_METHOD_DECL, 
+			     /* is_optional= */ false);
 	}
     }
 }
Index: gcc/objc/objc-act.h
===================================================================
--- gcc/objc/objc-act.h	(revision 164748)
+++ gcc/objc/objc-act.h	(working copy)
@@ -38,7 +38,7 @@  tree objc_eh_personality (void);
 /* Objective-C structures */
 
 #define CLASS_LANG_SLOT_ELTS		5
-#define PROTOCOL_LANG_SLOT_ELTS		2
+#define PROTOCOL_LANG_SLOT_ELTS		4
 #define OBJC_INFO_SLOT_ELTS		2
 
 /* KEYWORD_DECL */
@@ -71,6 +71,8 @@  tree objc_eh_personality (void);
 #define PROTOCOL_CLS_METHODS(CLASS) ((CLASS)->type.maxval)
 #define PROTOCOL_FORWARD_DECL(CLASS) TREE_VEC_ELT (TYPE_LANG_SLOT_1 (CLASS), 1)
 #define PROTOCOL_DEFINED(CLASS) TREE_USED (CLASS)
+#define PROTOCOL_OPTIONAL_CLS_METHODS(CLASS) TREE_VEC_ELT (TYPE_LANG_SLOT_1 (CLASS), 2)
+#define PROTOCOL_OPTIONAL_NST_METHODS(CLASS) TREE_VEC_ELT (TYPE_LANG_SLOT_1 (CLASS), 3)
 
 /* ObjC-specific information pertaining to RECORD_TYPEs are stored in
    the LANG_SPECIFIC structures, which may itself need allocating first.  */
Index: gcc/cp/parser.c
===================================================================
--- gcc/cp/parser.c	(revision 164748)
+++ gcc/cp/parser.c	(working copy)
@@ -21597,6 +21597,17 @@  cp_parser_objc_interstitial_code (cp_parser* parse
   /* Allow stray semicolons.  */
   else if (token->type == CPP_SEMICOLON)
     cp_lexer_consume_token (parser->lexer);
+  /* Mark methods as optional or required, when building protocols.  */
+  else if (token->keyword == RID_AT_OPTIONAL)
+    {
+      cp_lexer_consume_token (parser->lexer);
+      objc_set_method_opt (true);
+    }
+  else if (token->keyword == RID_AT_REQUIRED)
+    {
+      cp_lexer_consume_token (parser->lexer);
+      objc_set_method_opt (false);
+    }
   /* Finally, try to parse a block-declaration, or a function-definition.  */
   else
     cp_parser_block_declaration (parser, /*statement_p=*/false);