path_is_absolute: narrow return type and assert param type

functionMap.php

@@ -181,6 +181,7 @@
     'newblog_notify_siteadmin' => [null, 'deprecated' => "''"],
     'next_posts' => ['($display is true ? void : string)'],
     'paginate_links' => ["(\$args is array{total: int<min, 1>}&array ? void : (\$args is array{type: 'array'}&array ? list<string> : string))"],
+    'path_is_absolute' => ['($path is non-falsy-string ? bool : false)', '@phpstan-assert-if-true =non-falsy-string $path' => ''],
     'path_join' => ['non-falsy-string'],
     'post_type_archive_title' => ['($display is true ? void : string|void)'],
     'prep_atom_text_construct' => ["array{'html'|'text'|'xhtml', string}"],

tests/data/assert/path-is-absolute.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpStubs\WordPress\Core\Tests;
+
+use function path_is_absolute;
+use function PHPStan\Testing\assertType;
+
+$path = Faker::string();
+if (path_is_absolute($path)) {
+    assertType('non-falsy-string', $path);
+}
+if (! path_is_absolute($path)) {
+    assertType('string', $path);
+}
+
+$path = Faker::nonFalsyString();
+if (path_is_absolute($path)) {
+    assertType('non-falsy-string', $path);
+}
+if (! path_is_absolute($path)) {
+    assertType('non-falsy-string', $path);
+}

tests/data/return/path-is-absolute.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpStubs\WordPress\Core\Tests;
+
+use function path_is_absolute;
+use function PHPStan\Testing\assertType;
+
+assertType('false', path_is_absolute(''));
+assertType('false', path_is_absolute('0'));
+assertType('bool', path_is_absolute('foo'));
+assertType('bool', path_is_absolute(Faker::string()));

wordpress-stubs.php

@@ -130055,6 +130055,8 @@ function wp_mkdir_p($target)
      *
      * @param string $path File path.
      * @return bool True if path is absolute, false is not absolute.
+     * @phpstan-assert-if-true =non-falsy-string $path
+     * @phpstan-return ($path is non-falsy-string ? bool : false)
      */
     function path_is_absolute($path)
     {