Use constant instead of function call.

Debug.php

@@ -44,7 +44,7 @@ class Debug
         error_reporting(-1);
 
         ErrorHandler::register($errorReportingLevel, $displayErrors);
-        if ('cli' !== php_sapi_name()) {
+        if ('cli' !== PHP_SAPI) {
             ExceptionHandler::register();
         // CLI - display errors only if they're not already logged to STDERR
         } elseif ($displayErrors && (!ini_get('log_errors') || ini_get('error_log'))) {

README.md

@@ -1,44 +1,13 @@
 Debug Component
 ===============
 
-Debug provides tools to make debugging easier.
-
-Enabling all debug tools is as easy as calling the `enable()` method on the
-main `Debug` class:
-
-```php
-use Symfony\Component\Debug\Debug;
-
-Debug::enable();
-```
-
-You can also use the tools individually:
-
-```php
-use Symfony\Component\Debug\ErrorHandler;
-use Symfony\Component\Debug\ExceptionHandler;
-
-error_reporting(-1);
-
-ErrorHandler::register($errorReportingLevel);
-if ('cli' !== php_sapi_name()) {
-    ExceptionHandler::register();
-} elseif (!ini_get('log_errors') || ini_get('error_log')) {
-    ini_set('display_errors', 1);
-}
-```
-
-Note that the `Debug::enable()` call also registers the debug class loader
-from the Symfony ClassLoader component when available.
-
-This component can optionally take advantage of the features of the HttpKernel
-and HttpFoundation components.
+The Debug component provides tools to ease debugging PHP code.
 
 Resources
 ---------
 
-You can run the unit tests with the following command:
-
-    $ cd path/to/Symfony/Component/Debug/
-    $ composer install
-    $ phpunit
+  * [Documentation](https://symfony.com/doc/current/components/debug/index.html)
+  * [Contributing](https://symfony.com/doc/current/contributing/index.html)
+  * [Report issues](https://github.com/symfony/symfony/issues) and
+    [send Pull Requests](https://github.com/symfony/symfony/pulls)
+    in the [main Symfony repository](https://github.com/symfony/symfony)