diff --git a/generated/array.php b/generated/array.php
index 4a6b844f..0842d4ff 100644
--- a/generated/array.php
+++ b/generated/array.php
@@ -28,6 +28,36 @@ function array_combine(array $keys, array $values): array
 }
 
 
+/**
+ * array_flip returns an array in flip
+ * order, i.e. keys from array become values and values
+ * from array become keys.
+ *
+ * Note that the values of array need to be valid
+ * keys, i.e. they need to be either integer or
+ * string. A warning will be emitted if a value has the wrong
+ * type, and the key/value pair in question will not be included
+ * in the result.
+ *
+ * If a value has several occurrences, the latest key will be
+ * used as its value, and all others will be lost.
+ *
+ * @param array $array An array of key/value pairs to be flipped.
+ * @return array Returns the flipped array on success and NULL on failure.
+ * @throws ArrayException
+ *
+ */
+function array_flip(array $array): array
+{
+    error_clear_last();
+    $result = \array_flip($array);
+    if ($result === null) {
+        throw ArrayException::createFromPhpError();
+    }
+    return $result;
+}
+
+
 /**
  * array_multisort can be used to sort several
  * arrays at once, or a multi-dimensional array by one or more
diff --git a/generated/functionsList.php b/generated/functionsList.php
index 10ccc565..00a1d286 100644
--- a/generated/functionsList.php
+++ b/generated/functionsList.php
@@ -26,6 +26,7 @@
     'apcu_inc',
     'apcu_sma_info',
     'array_combine',
+    'array_flip',
     'array_multisort',
     'array_walk_recursive',
     'arsort',
@@ -475,6 +476,7 @@
     'define',
     'highlight_file',
     'highlight_string',
+    'sapi_windows_cp_conv',
     'sapi_windows_cp_set',
     'sapi_windows_vt100_support',
     'sleep',
@@ -900,6 +902,8 @@
     'simplexml_load_file',
     'simplexml_load_string',
     'socket_accept',
+    'socket_addrinfo_bind',
+    'socket_addrinfo_connect',
     'socket_bind',
     'socket_connect',
     'socket_create_listen',
@@ -909,6 +913,7 @@
     'socket_get_option',
     'socket_getpeername',
     'socket_getsockname',
+    'socket_import_stream',
     'socket_listen',
     'socket_read',
     'socket_send',
diff --git a/generated/misc.php b/generated/misc.php
index 41da6ae6..9d50256c 100644
--- a/generated/misc.php
+++ b/generated/misc.php
@@ -92,6 +92,30 @@ function highlight_string(string $str, bool $return = false)
 }
 
 
+/**
+ * Convert string from one codepage to another.
+ *
+ * @param int|string $in_codepage The codepage of the subject string.
+ * Either the codepage name or identifier.
+ * @param int|string $out_codepage The codepage to convert the subject string to.
+ * Either the codepage name or identifier.
+ * @param string $subject The string to convert.
+ * @return string The subject string converted to
+ * out_codepage, or NULL on failure.
+ * @throws MiscException
+ *
+ */
+function sapi_windows_cp_conv($in_codepage, $out_codepage, string $subject): string
+{
+    error_clear_last();
+    $result = \sapi_windows_cp_conv($in_codepage, $out_codepage, $subject);
+    if ($result === null) {
+        throw MiscException::createFromPhpError();
+    }
+    return $result;
+}
+
+
 /**
  * Set the codepage of the current process.
  *
diff --git a/generated/sockets.php b/generated/sockets.php
index d9e0b524..36e2d4e8 100644
--- a/generated/sockets.php
+++ b/generated/sockets.php
@@ -45,6 +45,46 @@ function socket_accept($socket)
 }
 
 
+/**
+ * Create a Socket resource, and bind it to the provided AddrInfo resource.  The return
+ * value of this function may be used with socket_listen.
+ *
+ * @param resource $addr Resource created from socket_addrinfo_lookup().
+ * @return resource|null Returns a Socket resource on success or NULL on failure.
+ * @throws SocketsException
+ *
+ */
+function socket_addrinfo_bind($addr)
+{
+    error_clear_last();
+    $result = \socket_addrinfo_bind($addr);
+    if ($result === null) {
+        throw SocketsException::createFromPhpError();
+    }
+    return $result;
+}
+
+
+/**
+ * Create a Socket resource, and connect it to the provided AddrInfo resource.  The return
+ * value of this function may be used with the rest of the socket functions.
+ *
+ * @param resource $addr Resource created from socket_addrinfo_lookup()
+ * @return resource|null Returns a Socket resource on success or NULL on failure.
+ * @throws SocketsException
+ *
+ */
+function socket_addrinfo_connect($addr)
+{
+    error_clear_last();
+    $result = \socket_addrinfo_connect($addr);
+    if ($result === null) {
+        throw SocketsException::createFromPhpError();
+    }
+    return $result;
+}
+
+
 /**
  * Binds the name given in address to the socket
  * described by socket. This has to be done before
@@ -336,6 +376,25 @@ function socket_getsockname($socket, ?string &$addr, ?int &$port = null): void
 }
 
 
+/**
+ * Imports a stream that encapsulates a socket into a socket extension resource.
+ *
+ * @param resource $stream The stream resource to import.
+ * @return resource Returns FALSE or NULL on failure.
+ * @throws SocketsException
+ *
+ */
+function socket_import_stream($stream)
+{
+    error_clear_last();
+    $result = \socket_import_stream($stream);
+    if ($result === null) {
+        throw SocketsException::createFromPhpError();
+    }
+    return $result;
+}
+
+
 /**
  * After the socket socket has been created
  * using socket_create and bound to a name with
diff --git a/generator/src/DocPage.php b/generator/src/DocPage.php
index 0c34f28f..f9568209 100644
--- a/generator/src/DocPage.php
+++ b/generator/src/DocPage.php
@@ -21,32 +21,39 @@ public function __construct(string $_path)
         $this->path = $_path;
     }
 
-    /*
-     * Detect function which didn't return FALSE on error.
-     *
-     * @return bool
-     */
-    public function detectFalsyFunction(): bool
+    // Ignore function if it was removed before PHP 7.1
+    private function getIsDeprecated(string $file): bool
     {
-        $file = file_get_contents($this->path);
-
         if (preg_match('/&warn\.deprecated\.function-(\d+-\d+-\d+)\.removed-(\d+-\d+-\d+)/', $file, $matches)) {
             $removedVersion = $matches[2];
             [$major, $minor] = explode('-', $removedVersion);
             if ($major < 7 || ($major == 7 && $minor == 0)) {
-                // Ignore function if it was removed before PHP 7.1
-                return false;
+                return true;
             }
         }
+
         if (preg_match('/&warn\.removed\.function-(\d+-\d+-\d+)/', $file, $matches) && isset($matches[2])) {
             $removedVersion = $matches[2];
             [$major, $minor] = explode('-', $removedVersion);
             if ($major < 7 || ($major == 7 && $minor == 0)) {
-                // Ignore function if it was removed before PHP 7.1
-                return false;
+                return true;
             }
         }
 
+        return false;
+    }
+
+    /*
+     * Detect function which return FALSE on error.
+     */
+    public function detectFalsyFunction(): bool
+    {
+        $file = file_get_contents($this->path);
+
+        if ($this->getIsDeprecated($file)) {
+            return false;
+        }
+
         if (preg_match('/&false;\s+on\s+error/m', $file)) {
             return true;
         }
@@ -90,6 +97,24 @@ public function detectFalsyFunction(): bool
         return false;
     }
 
+    /*
+     * Detect function which return NULL on error.
+     */
+    public function detectNullsyFunction(): bool
+    {
+        $file = \file_get_contents($this->path);
+
+        if ($this->getIsDeprecated($file)) {
+            return false;
+        }
+
+        if (preg_match('/&null;\s+on\s+failure/', $file)) {
+            return true;
+        }
+
+        return false;
+    }
+
 
     /**
      * @return \SimpleXMLElement[]
diff --git a/generator/src/Method.php b/generator/src/Method.php
index 0ff014db..687d4474 100644
--- a/generator/src/Method.php
+++ b/generator/src/Method.php
@@ -7,6 +7,8 @@
 
 class Method
 {
+    const FALSY_TYPE = 1;
+    const NULLSY_TYPE = 2;
     /**
      * @var \SimpleXMLElement
      */
@@ -27,13 +29,18 @@ class Method
      * @var PhpStanFunctionMapReader
      */
     private $phpStanFunctionMapReader;
+    /**
+     * @var int
+     */
+    private $errorType;
 
-    public function __construct(\SimpleXMLElement $_functionObject, \SimpleXMLElement $rootEntity, string $moduleName, PhpStanFunctionMapReader $phpStanFunctionMapReader)
+    public function __construct(\SimpleXMLElement $_functionObject, \SimpleXMLElement $rootEntity, string $moduleName, PhpStanFunctionMapReader $phpStanFunctionMapReader, int $errorType)
     {
         $this->functionObject = $_functionObject;
         $this->rootEntity = $rootEntity;
         $this->moduleName = $moduleName;
         $this->phpStanFunctionMapReader = $phpStanFunctionMapReader;
+        $this->errorType = $errorType;
     }
 
     public function getFunctionName(): string
@@ -41,6 +48,11 @@ public function getFunctionName(): string
         return $this->functionObject->methodname->__toString();
     }
 
+    public function getErrorType(): int
+    {
+        return $this->errorType;
+    }
+
     public function getReturnType(): string
     {
         // If the function returns a boolean, since false is for error, true is for success.
diff --git a/generator/src/Parameter.php b/generator/src/Parameter.php
index 24ff990d..a32eb13b 100644
--- a/generator/src/Parameter.php
+++ b/generator/src/Parameter.php
@@ -157,4 +157,9 @@ private function getInnerXml(\SimpleXMLElement $SimpleXMLElement): string
         $inner_xml = trim($inner_xml);
         return $inner_xml;
     }
+
+    public function isTypeable(): bool
+    {
+        return $this->getType() !== 'mixed' && $this->getType() !== 'resource' && \count(\explode("|", $this->getType())) < 2;
+    }
 }
diff --git a/generator/src/Scanner.php b/generator/src/Scanner.php
index e53cfffb..f48ae58e 100644
--- a/generator/src/Scanner.php
+++ b/generator/src/Scanner.php
@@ -94,7 +94,11 @@ public function getMethods(array $paths): array
             }
 
             $docPage = new DocPage($path);
-            if ($docPage->detectFalsyFunction()) {
+            $isFalsy = $docPage->detectFalsyFunction();
+            $isNullsy = $docPage->detectNullsyFunction();
+            if ($isFalsy || $isNullsy) {
+                $errorType = $isFalsy ? Method::FALSY_TYPE : Method::NULLSY_TYPE;
+
                 $functionObjects = $docPage->getMethodSynopsis();
                 if (count($functionObjects) > 1) {
                     $overloadedFunctions = array_merge($overloadedFunctions, \array_map(function ($functionObject) {
@@ -107,7 +111,7 @@ public function getMethods(array $paths): array
                 }
                 $rootEntity = $docPage->loadAndResolveFile();
                 foreach ($functionObjects as $functionObject) {
-                    $function = new Method($functionObject, $rootEntity, $docPage->getModule(), $phpStanFunctionMapReader);
+                    $function = new Method($functionObject, $rootEntity, $docPage->getModule(), $phpStanFunctionMapReader, $errorType);
                     if (isset($ignoredFunctions[$function->getFunctionName()])) {
                         continue;
                     }
diff --git a/generator/src/WritePhpFunction.php b/generator/src/WritePhpFunction.php
index 7d0dd8db..47acd58f 100644
--- a/generator/src/WritePhpFunction.php
+++ b/generator/src/WritePhpFunction.php
@@ -99,12 +99,24 @@ private function writePhpFunction(): string
 
     private function generateExceptionCode(string $moduleName, Method $method) : string
     {
+        $errorValue = null;
+        switch ($method->getErrorType()) {
+            case Method::FALSY_TYPE:
+                $errorValue = 'false';
+                break;
+            case Method::NULLSY_TYPE:
+                $errorValue = 'null';
+                break;
+            default:
+                throw new \LogicException("Method doesn't have an error type");
+        }
+
         // Special case for CURL: we need the first argument of the method if this is a resource.
         if ($moduleName === 'Curl') {
             $params = $method->getParams();
             if (\count($params) > 0 && $params[0]->getParameter() === 'ch') {
                 return "
-    if (\$result === false) {
+    if (\$result === $errorValue) {
         throw CurlException::createFromCurlResource(\$ch);
     }
 ";
@@ -113,7 +125,7 @@ private function generateExceptionCode(string $moduleName, Method $method) : str
 
         $exceptionName = FileCreator::toExceptionName($moduleName);
         return "
-    if (\$result === false) {
+    if (\$result === $errorValue) {
         throw {$exceptionName}::createFromPhpError();
     }
 ";
@@ -130,7 +142,7 @@ private function displayParamsWithType(array $params): string
 
         foreach ($params as $param) {
             $paramAsString = '';
-            if ($param->getType() !== 'mixed' && $param->getType() !== 'resource') {
+            if ($param->isTypeable()) {
                 if ($param->isNullable()) {
                     $paramAsString .= '?';
                 }
diff --git a/generator/tests/DocPageTest.php b/generator/tests/DocPageTest.php
index 2e2b81ab..571a7e91 100644
--- a/generator/tests/DocPageTest.php
+++ b/generator/tests/DocPageTest.php
@@ -26,4 +26,13 @@ public function testDetectFalsyFunction()
         $this->assertTrue($mcryptDecrypt->detectFalsyFunction());
         $this->assertTrue($fsockopen->detectFalsyFunction());
     }
+
+    public function testDetectNullsyFunction()
+    {
+        $pregMatch = new DocPage(__DIR__ . '/../doc/doc-en/en/reference/array/functions/array-flip.xml');
+        $implode = new DocPage(__DIR__ . '/../doc/doc-en/en/reference/strings/functions/implode.xml');
+
+        $this->assertTrue($pregMatch->detectNullsyFunction());
+        $this->assertFalse($implode->detectNullsyFunction());
+    }
 }
diff --git a/generator/tests/MethodTest.php b/generator/tests/MethodTest.php
index 92e07182..6b00500e 100644
--- a/generator/tests/MethodTest.php
+++ b/generator/tests/MethodTest.php
@@ -11,7 +11,7 @@ public function testGetFunctionName()
     {
         $docPage = new DocPage(__DIR__ . '/../doc/doc-en/en/reference/pcre/functions/preg-match.xml');
         $xmlObject = $docPage->getMethodSynopsis();
-        $method = new Method($xmlObject[0], $docPage->loadAndResolveFile(), $docPage->getModule(), new PhpStanFunctionMapReader());
+        $method = new Method($xmlObject[0], $docPage->loadAndResolveFile(), $docPage->getModule(), new PhpStanFunctionMapReader(), Method::FALSY_TYPE);
         $name = $method->getFunctionName();
         $this->assertEquals('preg_match', $name);
     }
@@ -20,7 +20,7 @@ public function testGetFunctionType()
     {
         $docPage = new DocPage(__DIR__ . '/../doc/doc-en/en/reference/pcre/functions/preg-match.xml');
         $xmlObject = $docPage->getMethodSynopsis();
-        $method = new Method($xmlObject[0], $docPage->loadAndResolveFile(), $docPage->getModule(), new PhpStanFunctionMapReader());
+        $method = new Method($xmlObject[0], $docPage->loadAndResolveFile(), $docPage->getModule(), new PhpStanFunctionMapReader(), Method::FALSY_TYPE);
         $type = $method->getReturnType();
         $this->assertEquals('int', $type);
     }
@@ -29,7 +29,7 @@ public function testGetFunctionParam()
     {
         $docPage = new DocPage(__DIR__ . '/../doc/doc-en/en/reference/pcre/functions/preg-match.xml');
         $xmlObject = $docPage->getMethodSynopsis();
-        $method = new Method($xmlObject[0], $docPage->loadAndResolveFile(), $docPage->getModule(), new PhpStanFunctionMapReader());
+        $method = new Method($xmlObject[0], $docPage->loadAndResolveFile(), $docPage->getModule(), new PhpStanFunctionMapReader(), Method::FALSY_TYPE);
         $params = $method->getParams();
         $this->assertEquals('string', $params[0]->getType());
         $this->assertEquals('pattern', $params[0]->getParameter());
@@ -39,7 +39,7 @@ public function testGetInitializer()
     {
         $docPage = new DocPage(__DIR__ . '/../doc/doc-en/en/reference/apc/functions/apc-cache-info.xml');
         $xmlObject = $docPage->getMethodSynopsis();
-        $method = new Method($xmlObject[0], $docPage->loadAndResolveFile(), $docPage->getModule(), new PhpStanFunctionMapReader());
+        $method = new Method($xmlObject[0], $docPage->loadAndResolveFile(), $docPage->getModule(), new PhpStanFunctionMapReader(), Method::FALSY_TYPE);
 
         $params = $method->getParams();
         $this->assertEquals('', $params[0]->getDefaultValue());
diff --git a/rector-migrate.yml b/rector-migrate.yml
index b883ec01..702cf12c 100644
--- a/rector-migrate.yml
+++ b/rector-migrate.yml
@@ -29,6 +29,7 @@ services:
       apcu_inc: 'Safe\apcu_inc'
       apcu_sma_info: 'Safe\apcu_sma_info'
       array_combine: 'Safe\array_combine'
+      array_flip: 'Safe\array_flip'
       array_multisort: 'Safe\array_multisort'
       array_walk_recursive: 'Safe\array_walk_recursive'
       arsort: 'Safe\arsort'
@@ -478,6 +479,7 @@ services:
       define: 'Safe\define'
       highlight_file: 'Safe\highlight_file'
       highlight_string: 'Safe\highlight_string'
+      sapi_windows_cp_conv: 'Safe\sapi_windows_cp_conv'
       sapi_windows_cp_set: 'Safe\sapi_windows_cp_set'
       sapi_windows_vt100_support: 'Safe\sapi_windows_vt100_support'
       sleep: 'Safe\sleep'
@@ -903,6 +905,8 @@ services:
       simplexml_load_file: 'Safe\simplexml_load_file'
       simplexml_load_string: 'Safe\simplexml_load_string'
       socket_accept: 'Safe\socket_accept'
+      socket_addrinfo_bind: 'Safe\socket_addrinfo_bind'
+      socket_addrinfo_connect: 'Safe\socket_addrinfo_connect'
       socket_bind: 'Safe\socket_bind'
       socket_connect: 'Safe\socket_connect'
       socket_create_listen: 'Safe\socket_create_listen'
@@ -912,6 +916,7 @@ services:
       socket_get_option: 'Safe\socket_get_option'
       socket_getpeername: 'Safe\socket_getpeername'
       socket_getsockname: 'Safe\socket_getsockname'
+      socket_import_stream: 'Safe\socket_import_stream'
       socket_listen: 'Safe\socket_listen'
       socket_read: 'Safe\socket_read'
       socket_send: 'Safe\socket_send'