diff --git a/metagen.inc.php b/metagen.inc.php
index a12c0c3..e1ff14b 100644
--- a/metagen.inc.php
+++ b/metagen.inc.php
@@ -10,12 +10,11 @@ class mtgTypeRef implements mtgType
   private static $unresolved = array();
 
   private $name;
-  private $file;
-  private $line;
   private $module;
   private $resolved;
+  private $origin;
 
-  function __construct($name_or_resolved, mtgMetaParsedModule $module = null, $file = '', $line= 0)
+  function __construct($name_or_resolved, mtgMetaParsedModule $module = null, mtgOrigin $origin = null)
   {
     if(is_object($name_or_resolved))
     {
@@ -33,8 +32,7 @@ class mtgTypeRef implements mtgType
     }
 
     $this->module = $module;
-    $this->file = $file;
-    $this->line = $line;
+    $this->origin = $origin ?? new mtgOrigin();
 
   }
 
@@ -67,7 +65,7 @@ class mtgTypeRef implements mtgType
       return $this->resolved;
     }
     else
-      throw new Exception("{$this->file}@{$this->line} : Symbol '{$this->name}' not found");
+      throw new Exception("{$this->origin} : Symbol '{$this->name}' not found");
   } 
 
   function __toString()
@@ -123,6 +121,12 @@ class mtgMetaInfo
       return $this->units[$id];
     throw new Exception("Unit '$id' not found");
   }
+
+  function validate()
+  {
+    foreach($this->units as $u)
+      $u->object->validate($this);
+  }
 }
 
 abstract class mtgMetaUnit
@@ -131,6 +135,8 @@ abstract class mtgMetaUnit
 
   protected $tokens = array();
 
+  protected $origin;
+
   function getTokens()
   {
     return $this->tokens;
@@ -155,9 +161,38 @@ abstract class mtgMetaUnit
   {
     return array_key_exists($name, $this->tokens);
   }
+
+  function setOrigin(mtgOrigin $origin)
+  {
+    $this->origin = $origin;
+  }
+
+  function getOrigin()
+  {
+    return $this->origin;
+  }
+
+  abstract function validate(mtgMetaInfo $meta);
 }
 
-class mtgUserType extends mtgMetaUnit implements mtgType
+class mtgOrigin
+{
+  public $file;
+  public $line;
+
+  function __construct($file = '', $line = 0)
+  {
+    $this->file = $file;
+    $this->line = $line;
+  }
+
+  function __toString()
+  {
+    return "{$this->file}@{$this->line}";
+  }
+}
+
+abstract class mtgUserType extends mtgMetaUnit implements mtgType
 {
   protected $name;
 
@@ -214,6 +249,34 @@ class mtgMetaStruct extends mtgUserType
     $this->implements = $implements;
   }
 
+  function validate(mtgMetaInfo $meta)
+  {
+    $parent = $this->getParent();
+    while($parent != null)
+    {
+      foreach($this->fields as $name => $_)
+        if($parent->hasField($name))
+          throw new Exception("{$this->origin} : Parent struct '{$parent->getName()}' already has field '{$name}'");
+
+      foreach($this->funcs as $name => $_)
+        if($parent->hasFunc($name))
+          throw new Exception("{$this->origin} : Parent struct '{$parent->getName()}' already has func '{$name}'");
+
+      $parent = $parent->getParent();
+    }
+
+    $s = new SplObjectStorage();
+    foreach($this->getImplements() as $imp)
+    {
+      if(!($imp instanceof mtgMetaInterface))
+        throw new Exception("{$this->origin} : Not an interface '{$imp}'");
+
+      if($s->contains($imp))
+        throw new Exception("{$this->origin} : Duplicate interface reference '{$imp->getName()}'");
+      $s->attach($imp);
+    }
+  }
+
   function getParent()
   {
     return $this->parent ? $this->parent->resolve() : null;
@@ -315,6 +378,8 @@ class mtgMetaInterface extends mtgUserType
     $this->tokens = $tokens;
   }
 
+  function validate(mtgMetaInfo $meta) {}
+
   function getImplements()
   {
     if(!$this->implements)
@@ -363,6 +428,8 @@ class mtgMetaFunc extends mtgMetaUnit implements mtgType
     $this->name = $name;
   }
 
+  function validate(mtgMetaInfo $meta) {}
+
   function getMetaId()
   {
     return $this->name;
@@ -445,6 +512,8 @@ class mtgMetaRPC extends mtgMetaUnit
     $this->tokens = $tokens;
   }
 
+  function validate(mtgMetaInfo $meta) {}
+
   function getMetaId()
   {
     return $this->code;
@@ -732,6 +801,8 @@ class mtgMetaEnum extends mtgUserType
 {
   private $values = array();
 
+  function validate(mtgMetaInfo $meta) {}
+
   function addValue($value_name, $value)
   {
     if(isset($this->values[$value_name]))
diff --git a/parser.inc.php b/parser.inc.php
index a1cc931..806c9f2 100644
--- a/parser.inc.php
+++ b/parser.inc.php
@@ -105,8 +105,6 @@ class mtgMetaInfoParser
       throw new Exception("No such file '$raw_file'");
 
     $this->_parse($file);
-
-    mtgTypeRef::checkAllResolved();
   }
 
   private function _parse($file)
@@ -206,26 +204,30 @@ class mtgMetaInfoParser
       
       if($this->token == self::T_Func)
       {
+        $origin = new mtgOrigin($this->file, $this->line);
         $func_type = $this->_parseFuncType();
-        $type = new mtgTypeRef($func_type, $this->module, $this->file, $this->line);
+        $type = new mtgTypeRef($func_type, $this->module, $origin);
       }
       else if($this->token == self::T_Identifier)
       {
+        $origin = new mtgOrigin($this->file, $this->line);
         $type_name = $this->_parseDotName();
-        $type = new mtgTypeRef($type_name, $this->module, $this->file, $this->line);
+        $type = new mtgTypeRef($type_name, $this->module, $origin);
       }
       else
       {
+        $origin = new mtgOrigin($this->file, $this->line);
         $type_name = $this->attribute;
-        $type = new mtgTypeRef(new mtgBuiltinType($type_name), $this->module, $this->file, $this->line);
+        $type = new mtgTypeRef(new mtgBuiltinType($type_name), $this->module, $origin);
         $this->_next();
       }
 
       if($this->token == ord('['))
       {
+        $origin = new mtgOrigin($this->file, $this->line);
         $this->_next();
         $this->_checkThenNext(']');
-        $type = new mtgTypeRef(new mtgArrType($type), $this->module, $this->file, $this->line);
+        $type = new mtgTypeRef(new mtgArrType($type), $this->module, $origin);
       }
       $types[] = $type;
 
@@ -238,7 +240,7 @@ class mtgMetaInfoParser
     }
 
     if(sizeof($types) > 1)
-      return new mtgTypeRef(new mtgMultiType($types), $this->module, $this->file, $this->line);
+      return new mtgTypeRef(new mtgMultiType($types), $this->module, new mtgOrigin($this->file, $this->line));
     else
       return $types[0];
   }
@@ -511,14 +513,16 @@ class mtgMetaInfoParser
   private function _parseStruct()
   {
     $this->_next();
+    $struct_origin = new mtgOrigin($this->file, $this->line);
     $name = $this->_parseDotName();
 
     $parent = null;
     if($this->token == self::T_Extends)
     {
       $this->_next();
+      $origin = new mtgOrigin($this->file, $this->line);
       $parent_name = $this->_checkThenNext(self::T_Identifier);
-      $parent = new mtgTypeRef($parent_name, $this->module, $this->file, $this->line);
+      $parent = new mtgTypeRef($parent_name, $this->module, $origin);
     }
 
     $implements = array();
@@ -527,12 +531,14 @@ class mtgMetaInfoParser
       do 
       {
         $this->_next();
+        $origin = new mtgOrigin($this->file, $this->line);
         $if_name = $this->_checkThenNext(self::T_Identifier);
-        $implements[] = new mtgTypeRef($if_name, $this->module, $this->file, $this->line);
+        $implements[] = new mtgTypeRef($if_name, $this->module, $origin);
       } while($this->token == ord(','));
     }
 
     $s = new mtgMetaStruct($name, array(), $parent, array(), $implements);
+    $s->setOrigin($struct_origin);
     $this->_addUnit(new mtgMetaInfoUnit($this->file, $s));
 
     $tokens = $this->shared_tokens;
@@ -577,10 +583,15 @@ class mtgMetaInfoParser
       $tokens = array_merge($tokens, $this->_parsePropTokens());
     $s->setTokens($tokens);
 
-    $this->_next();
-    $funcs = $this->_parseFuncs();
-    foreach($funcs as $fn)
-      $s->addFunc($fn);
+    if($this->token !== self::T_End)
+    {
+      $this->_next();
+      $funcs = $this->_parseFuncs();
+      foreach($funcs as $fn)
+        $s->addFunc($fn);
+    }
+    else
+      $this->_next();
   }
 
   private function _parseRPC()
@@ -938,6 +949,11 @@ function mtg_parse_meta(array $meta_srcs, $valid_tokens = null, $inc_path = null
   $meta = new mtgMetaInfo();
   foreach($meta_srcs as $src)
     mtg_load_meta($meta, $meta_parser, $src);
+
+  $meta->validate();
+
+  mtgTypeRef::checkAllResolved();
+
   return $meta;
 }