diff --git a/lib/Twig/Autoloader.php b/lib/Twig/Autoloader.php
index 2bd3fcc13..2af5157e7 100644
--- a/lib/Twig/Autoloader.php
+++ b/lib/Twig/Autoloader.php
@@ -25,6 +25,8 @@ class Twig_Autoloader
      */
     public static function register($prepend = false)
     {
+        @trigger_error('Using Twig_Autoloader is deprecated. Use Composer instead.', E_USER_DEPRECATED);
+
         if (PHP_VERSION_ID < 50300) {
             spl_autoload_register(array(__CLASS__, 'autoload'));
         } else {
diff --git a/lib/Twig/Environment.php b/lib/Twig/Environment.php
index b7d470b1f..68517fdba 100644
--- a/lib/Twig/Environment.php
+++ b/lib/Twig/Environment.php
@@ -86,6 +86,8 @@ class Twig_Environment
     {
         if (null !== $loader) {
             $this->setLoader($loader);
+        } else {
+            @trigger_error('Not passing a Twig_LoaderInterface as the first constructor argument of Twig_Environment is deprecated.', E_USER_DEPRECATED);
         }
 
         $options = array_merge(array(
@@ -448,6 +450,8 @@ class Twig_Environment
      */
     public function clearTemplateCache()
     {
+        @trigger_error(sprintf('%s is deprecated and will be removed in Twig 2.0.', __METHOD__), E_USER_DEPRECATED);
+
         $this->loadedTemplates = array();
     }
 
@@ -711,6 +715,8 @@ class Twig_Environment
      */
     public function removeExtension($name)
     {
+        @trigger_error(sprintf('%s is deprecated and will be removed in Twig 2.0.', __METHOD__), E_USER_DEPRECATED);
+
         if ($this->extensionInitialized) {
             throw new LogicException(sprintf('Unable to remove extension "%s" as extensions have already been initialized.', $name));
         }
@@ -830,6 +836,8 @@ class Twig_Environment
         if ($name instanceof Twig_SimpleFilter) {
             $filter = $name;
             $name = $filter->getName();
+        } else {
+            @trigger_error(sprintf('Passing a name as a first argument to %s is deprecated. Pass an instance of "Twig_SimpleFilter" instead when defining filter "%s".', __METHOD__, $name), E_USER_DEPRECATED);
         }
 
         if ($this->extensionInitialized) {
@@ -919,6 +927,8 @@ class Twig_Environment
         if ($name instanceof Twig_SimpleTest) {
             $test = $name;
             $name = $test->getName();
+        } else {
+            @trigger_error(sprintf('Passing a name as a first argument to %s is deprecated. Pass an instance of "Twig_SimpleTest" instead when defining test "%s".', __METHOD__, $name), E_USER_DEPRECATED);
         }
 
         if ($this->extensionInitialized) {
@@ -977,6 +987,8 @@ class Twig_Environment
         if ($name instanceof Twig_SimpleFunction) {
             $function = $name;
             $name = $function->getName();
+        } else {
+            @trigger_error(sprintf('Passing a name as a first argument to %s is deprecated. Pass an instance of "Twig_SimpleFunction" instead when defining function "%s".', __METHOD__, $name), E_USER_DEPRECATED);
         }
 
         if ($this->extensionInitialized) {
@@ -1067,11 +1079,11 @@ class Twig_Environment
                 $this->globals = $this->initGlobals();
             }
 
-            /* This condition must be uncommented in Twig 2.0
             if (!array_key_exists($name, $this->globals)) {
-                throw new LogicException(sprintf('Unable to add global "%s" as the runtime or the extensions have already been initialized.', $name));
+                // The deprecation notice must be turned into the following exception in Twig 2.0
+                @trigger_error(sprintf('Registering global variable "%s" at runtime or when the extensions have already been initialized is deprecated.', $name), E_USER_DEPRECATED);
+                //throw new LogicException(sprintf('Unable to add global "%s" as the runtime or the extensions have already been initialized.', $name));
             }
-            */
         }
 
         if ($this->extensionInitialized || $this->runtimeInitialized) {
@@ -1206,6 +1218,8 @@ class Twig_Environment
         foreach ($extension->getFilters() as $name => $filter) {
             if ($filter instanceof Twig_SimpleFilter) {
                 $name = $filter->getName();
+            } else {
+                @trigger_error(sprintf('Using an instance of "%s" for filter "%s" is deprecated. Use Twig_SimpleFilter instead.', get_class($filter), $name), E_USER_DEPRECATED);
             }
 
             $this->filters[$name] = $filter;
@@ -1215,6 +1229,8 @@ class Twig_Environment
         foreach ($extension->getFunctions() as $name => $function) {
             if ($function instanceof Twig_SimpleFunction) {
                 $name = $function->getName();
+            } else {
+                @trigger_error(sprintf('Using an instance of "%s" for function "%s" is deprecated. Use Twig_SimpleFunction instead.', get_class($filter), $name), E_USER_DEPRECATED);
             }
 
             $this->functions[$name] = $function;
@@ -1224,6 +1240,8 @@ class Twig_Environment
         foreach ($extension->getTests() as $name => $test) {
             if ($test instanceof Twig_SimpleTest) {
                 $name = $test->getName();
+            } else {
+                @trigger_error(sprintf('Using an instance of "%s" for test "%s" is deprecated. Use Twig_SimpleTest instead.', get_class($filter), $name), E_USER_DEPRECATED);
             }
 
             $this->tests[$name] = $test;
@@ -1234,6 +1252,8 @@ class Twig_Environment
             if ($parser instanceof Twig_TokenParserInterface) {
                 $this->parsers->addTokenParser($parser);
             } elseif ($parser instanceof Twig_TokenParserBrokerInterface) {
+                @trigger_error('Registering a Twig_TokenParserBrokerInterface instance is deprecated.', E_USER_DEPRECATED);
+
                 $this->parsers->addTokenParserBroker($parser);
             } else {
                 throw new LogicException('getTokenParsers() must return an array of Twig_TokenParserInterface or Twig_TokenParserBrokerInterface instances');
diff --git a/lib/Twig/Extension/Escaper.php b/lib/Twig/Extension/Escaper.php
index cf2020eec..52983fb29 100644
--- a/lib/Twig/Extension/Escaper.php
+++ b/lib/Twig/Extension/Escaper.php
@@ -61,6 +61,8 @@ class Twig_Extension_Escaper extends Twig_Extension
     {
         // for BC
         if (true === $defaultStrategy) {
+            @trigger_error('Using "true" as the default strategy is deprecated. Use "html" instead.', E_USER_DEPRECATED);
+
             $defaultStrategy = 'html';
         }
 
diff --git a/lib/Twig/Node.php b/lib/Twig/Node.php
index 1c78e7b27..40d67fe59 100644
--- a/lib/Twig/Node.php
+++ b/lib/Twig/Node.php
@@ -74,6 +74,8 @@ class Twig_Node implements Twig_NodeInterface
      */
     public function toXml($asDom = false)
     {
+        @trigger_error(sprintf('%s is deprecated.', __METHOD__), E_USER_DEPRECATED);
+
         $dom = new DOMDocument('1.0', 'UTF-8');
         $dom->formatOutput = true;
         $dom->appendChild($xml = $dom->createElement('twig'));
diff --git a/lib/Twig/Node/Expression/Name.php b/lib/Twig/Node/Expression/Name.php
index a6e0ff420..c062a213f 100644
--- a/lib/Twig/Node/Expression/Name.php
+++ b/lib/Twig/Node/Expression/Name.php
@@ -30,11 +30,19 @@ class Twig_Node_Expression_Name extends Twig_Node_Expression
 
         if ($this->getAttribute('is_defined_test')) {
             if ($this->isSpecial()) {
+                if ('_self' === $name) {
+                    @trigger_error(sprintf('Global variable "_self" is deprecated in %s at line %d', '?', $this->getLine()), E_USER_DEPRECATED);
+                }
+
                 $compiler->repr(true);
             } else {
                 $compiler->raw('array_key_exists(')->repr($name)->raw(', $context)');
             }
         } elseif ($this->isSpecial()) {
+            if ('_self' === $name) {
+                @trigger_error(sprintf('Global variable "_self" is deprecated in %s at line %d', '?', $this->getLine()), E_USER_DEPRECATED);
+            }
+
             $compiler->raw($this->specialVars[$name]);
         } elseif ($this->getAttribute('always_defined')) {
             $compiler
diff --git a/lib/Twig/TokenParser/AutoEscape.php b/lib/Twig/TokenParser/AutoEscape.php
index 275602883..a8a3d7aa1 100644
--- a/lib/Twig/TokenParser/AutoEscape.php
+++ b/lib/Twig/TokenParser/AutoEscape.php
@@ -57,6 +57,8 @@ class Twig_TokenParser_AutoEscape extends Twig_TokenParser
             }
 
             if ($compat && $stream->test(Twig_Token::NAME_TYPE)) {
+                @trigger_error('Using the autoescape tag with "true" or "false" before the strategy name is deprecated.', E_USER_DEPRECATED);
+
                 if (false === $value) {
                     throw new Twig_Error_Syntax('Unexpected escaping strategy as you set autoescaping to false.', $stream->getCurrent()->getLine(), $stream->getFilename());
                 }
diff --git a/test/Twig/Tests/Node/Expression/NameTest.php b/test/Twig/Tests/Node/Expression/NameTest.php
index 905d8ee9b..e605e9a50 100644
--- a/test/Twig/Tests/Node/Expression/NameTest.php
+++ b/test/Twig/Tests/Node/Expression/NameTest.php
@@ -21,7 +21,6 @@ class Twig_Tests_Node_Expression_NameTest extends Twig_Test_NodeTestCase
     public function getTests()
     {
         $node = new Twig_Node_Expression_Name('foo', 1);
-        $self = new Twig_Node_Expression_Name('_self', 1);
         $context = new Twig_Node_Expression_Name('_context', 1);
 
         $env = new Twig_Environment(null, array('strict_variables' => true));
@@ -30,7 +29,6 @@ class Twig_Tests_Node_Expression_NameTest extends Twig_Test_NodeTestCase
         return array(
             array($node, "// line 1\n".(PHP_VERSION_ID >= 50400 ? '(isset($context["foo"]) ? $context["foo"] : $this->getContext($context, "foo"))' : '$this->getContext($context, "foo")'), $env),
             array($node, $this->getVariableGetter('foo', 1), $env1),
-            array($self, "// line 1\n\$this"),
             array($context, "// line 1\n\$context"),
         );
     }