Widen callable type to allow empty string default value (#413)

* Widen type to allow default value in Custom_Background::__construct

* Widen type to allow default value in Custom_Image_Header::__construct

Author: IanDelMar

functionMap.php

@@ -268,6 +268,12 @@
     'wp_widgets_access_body_class' => ['non-falsy-string'],
     'zeroise' => ['($threshold is 0 ? lowercase-string&non-empty-string&numeric-string : ($number is int<0, max> ? lowercase-string&non-empty-string&numeric-string : lowercase-string&non-empty-string))', 'threshold' => 'int<0, max>'],
     // Classes, methods, and properties
+    'Custom_Background::$admin_header_callback' => [null, '@phpstan-var' => "''|callable(): void"],
+    'Custom_Background::$admin_image_div_callback' => [null, '@phpstan-var' => "''|callable(): void"],
+    'Custom_Background::__construct' => [null, 'admin_header_callback' => "''|callable(): void", 'admin_image_div_callback' => "''|callable(): void"],
+    'Custom_Image_Header::$admin_header_callback' => [null, '@phpstan-var' => "''|callable(): void"],
+    'Custom_Image_Header::$admin_image_div_callback' => [null, '@phpstan-var' => "''|callable(): void"],
+    'Custom_Image_Header::__construct' => [null, 'admin_image_div_callback' => "''|callable(): void"],
     'Custom_Image_Header::set_header_image' => [null, 'choice' => 'string|array{attachment_id: int<1, max>, url: string, width: int<0, max>, height: int<0, max>}'],
     'Custom_Image_Header::show_header_selector' => [null, 'type' => "'default'|'uploaded'"],
     'WP_Block_List' => [null, '@phpstan-implements' => 'ArrayAccess<int, \WP_Block>'],

tests/ParameterTypeTest.php

@@ -155,6 +155,26 @@ public function testCheckAjaxReferer(): void
         );
     }
 
+    public function testCustomBackground(): void
+    {
+        $this->analyse(
+            __DIR__ . '/data/param/custom-background.php',
+            [
+                ["Parameter #2 \$admin_image_div_callback of class Custom_Background constructor expects ''|(callable(): void), Closure(int): int given.", 20],
+            ]
+        );
+    }
+
+    public function testCustomImageHeader(): void
+    {
+        $this->analyse(
+            __DIR__ . '/data/param/custom-image-header.php',
+            [
+                ["Parameter #2 \$admin_image_div_callback of class Custom_Image_Header constructor expects ''|(callable(): void), Closure(int): int given.", 20],
+            ]
+        );
+    }
+
     public function testDoAction(): void
     {
         $this->analyse(

tests/data/param/custom-background.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpStubs\WordPress\Core\Tests;
+
+use Custom_Background;
+
+$compatibleCallback = static function (): void {
+    // Do nothing
+};
+$incompatibleCallback = static function (int $arg): int {
+    return $arg;
+};
+
+// Correct
+new Custom_Background('', ''); // Empty string as callback is allowed
+
+// Incorrect
+new Custom_Background($compatibleCallback, $incompatibleCallback);

tests/data/param/custom-image-header.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpStubs\WordPress\Core\Tests;
+
+use Custom_Image_Header;
+
+$compatibleCallback = static function (): void {
+    // Do nothing
+};
+$incompatibleCallback = static function (int $arg): int {
+    return $arg;
+};
+
+// Correct
+new Custom_Image_Header($compatibleCallback, ''); // Empty string as callback is allowed
+
+// Incorrect
+new Custom_Image_Header($compatibleCallback, $incompatibleCallback);

wordpress-stubs.php

@@ -1026,13 +1026,15 @@ class Custom_Background
          *
          * @since 3.0.0
          * @var callable
+         * @phpstan-var ''|callable(): void
          */
         public $admin_header_callback;
         /**
          * Callback for header div.
          *
          * @since 3.0.0
          * @var callable
+         * @phpstan-var ''|callable(): void
          */
         public $admin_image_div_callback;
         /**
@@ -1044,6 +1046,8 @@ class Custom_Background
          *                                           Default empty string.
          * @param callable $admin_image_div_callback Optional. Custom image div output callback.
          *                                           Default empty string.
+         * @phpstan-param ''|callable(): void $admin_header_callback
+         * @phpstan-param ''|callable(): void $admin_image_div_callback
          */
         public function __construct($admin_header_callback = '', $admin_image_div_callback = '')
         {
@@ -1145,13 +1149,15 @@ class Custom_Image_Header
          *
          * @since 2.1.0
          * @var callable
+         * @phpstan-var ''|callable(): void
          */
         public $admin_header_callback;
         /**
          * Callback for header div.
          *
          * @since 3.0.0
          * @var callable
+         * @phpstan-var ''|callable(): void
          */
         public $admin_image_div_callback;
         /**
@@ -1169,6 +1175,7 @@ class Custom_Image_Header
          * @param callable $admin_header_callback    Administration header callback.
          * @param callable $admin_image_div_callback Optional. Custom image div output callback.
          *                                           Default empty string.
+         * @phpstan-param ''|callable(): void $admin_image_div_callback
          */
         public function __construct($admin_header_callback, $admin_image_div_callback = '')
         {