--- gcc/cp/lex.c	2018/04/24 18:27:15	1.1.1.2
+++ gcc/cp/lex.c	2018/04/24 18:43:28	1.1.1.4
@@ -3313,6 +3313,14 @@ real_yylex ()
 		  token_buffer[0] = '^';
 		  token_buffer[1] = 0;
 		}
+	      else if (ptr->token == NAMESPACE)
+		{
+		  static int warned;
+		  if (! warned)
+		    warning ("namespaces are mostly broken in this version of g++");
+
+		  warned = 1;
+		}
 
 	      value = (int) ptr->token;
 	    }
@@ -3373,7 +3381,12 @@ real_yylex ()
 		&& DECL_INITIAL (tmp) != NULL_TREE
 		&& TREE_CODE (DECL_INITIAL (tmp)) == STRING_CST)
 	      {
-		yylval.ttype = DECL_INITIAL (tmp);
+		tree stringval = DECL_INITIAL (tmp);
+	      
+		/* Copy the string value so that we won't clobber anything
+		   if we put something in the TREE_CHAIN of this one.  */
+		yylval.ttype = build_string (TREE_STRING_LENGTH (stringval),
+					     TREE_STRING_POINTER (stringval));
 		value = STRING;
 	      }
 	  }