[Filesystem] depreacte calling isAbsolutePath with a null

UPGRADE-4.4.md

@@ -41,6 +41,11 @@ DependencyInjection
        arguments: [!tagged_iterator app.handler]
    ```
 
+Filesystem
+----------
+
+ * Support for passing a `null` value to `Filesystem::isAbsolutePath()` is deprecated.
+
 Form
 ----
 

UPGRADE-5.0.md

@@ -135,6 +135,7 @@ EventDispatcher
 Filesystem
 ----------
 
+ * The `Filesystem::isAbsolutePath()` method no longer supports `null` in the `$file` argument.
  * The `Filesystem::dumpFile()` method no longer supports arrays in the `$content` argument.
  * The `Filesystem::appendToFile()` method no longer supports arrays in the `$content` argument.
 

src/Symfony/Component/Filesystem/CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+4.4.0
+-----
+
+ * support for passing a `null` value to `Filesystem::isAbsolutePath()` is deprecated and will be removed in 5.0
+
 4.3.0
 -----
 

src/Symfony/Component/Filesystem/Filesystem.php

@@ -600,6 +600,10 @@ class Filesystem
      */
     public function isAbsolutePath($file)
     {
+        if (null === $file) {
+            @trigger_error(sprintf('Calling "%s()" with a null in the $file argument is deprecated since Symfony 4.4.', __METHOD__), E_USER_DEPRECATED);
+        }
+
         return strspn($file, '/\\', 0, 1)
             || (\strlen($file) > 3 && ctype_alpha($file[0])
                 && ':' === $file[1]

src/Symfony/Component/Filesystem/Tests/FilesystemTest.php

@@ -1397,10 +1397,18 @@ class FilesystemTest extends FilesystemTestCase
             ['var/lib', false],
             ['../var/lib', false],
             ['', false],
-            [null, false],
         ];
     }
 
+    /**
+     * @group legacy
+     * @expectedDeprecation Calling "Symfony\Component\Filesystem\Filesystem::isAbsolutePath()" with a null in the $file argument is deprecated since Symfony 4.4.
+     */
+    public function testIsAbsolutePathWithNull()
+    {
+        $this->assertFalse($this->filesystem->isAbsolutePath(null));
+    }
+
     public function testTempnam()
     {
         $dirname = $this->workspace;