Infer object type mysqli_fetch_object (#2675)

Author: staabm

resources/functionMap.php

@@ -7482,7 +7482,7 @@
 'mysqli_fetch_field_direct' => ['(stdClass&object{name: string, orgname: string, table: string, orgtable: string, def: string, db: string, catalog: "def", max_length: int, length: int, charsetnr: string, flags: int, type: int, decimals: int})|false', 'result'=>'mysqli_result', 'fieldnr'=>'int'],
 'mysqli_fetch_fields' => ['list<stdClass&object{name: string, orgname: string, table: string, orgtable: string, def: string, db: string, catalog: "def", max_length: int, length: int, charsetnr: string, flags: int, type: int, decimals: int}>', 'result'=>'mysqli_result'],
 'mysqli_fetch_lengths' => ['array|false', 'result'=>'mysqli_result'],
-'mysqli_fetch_object' => ['object|null', 'result'=>'mysqli_result', 'class_name='=>'string', 'params='=>'?array'],
+'mysqli_fetch_object' => ['object|false|null', 'result'=>'mysqli_result', 'class_name='=>'string', 'params='=>'?array'],
 'mysqli_fetch_row' => ['array|null', 'result'=>'mysqli_result'],
 'mysqli_field_count' => ['int', 'link'=>'mysqli'],
 'mysqli_field_seek' => ['bool', 'result'=>'mysqli_result', 'fieldnr'=>'int'],

stubs/mysqli.stub

@@ -14,8 +14,26 @@ class mysqli_result
      * @var int<0,max>|numeric-string
      */
     public $num_rows;
+
+    /**
+     * @template T of object
+     * @param class-string<T> $class
+     * @param array<mixed> $constructor_args
+     * @return T|null|false
+     */
+    function fetch_object(string $class = 'stdClass', array $constructor_args = []) {}
 }
 
+
+/**
+ * @template T of object
+ *
+ * @param class-string<T> $class
+ * @param array<mixed> $constructor_args
+ * @return T|null|false
+ */
+function mysqli_fetch_object(mysqli_result $result, string $class = 'stdClass', array $constructor_args = []) {}
+
 class mysqli_stmt
 {
     /**

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -1459,6 +1459,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-10037.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/PhpDoc/data/bug-10594.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/set-type-type-specifying.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/mysqli_fetch_object.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-10468.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6613.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-10187.php');

tests/PHPStan/Analyser/data/mysqli_fetch_object.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace MysqliFetchObject;
+
+use function PHPStan\Testing\assertType;
+
+function doFoo(\mysqli_result $result) {
+	assertType('stdClass|false|null', $result->fetch_object());
+	assertType('MysqliFetchObject\MyClass|false|null', $result->fetch_object(MyClass::class));
+
+	assertType('stdClass|false|null', mysqli_fetch_object($result));
+	assertType('MysqliFetchObject\MyClass|false|null', mysqli_fetch_object($result, MyClass::class));
+}
+
+class MyClass {}
+