From a9881e3afd4a105f0bd1391fb57a8e5c3462d2bc Mon Sep 17 00:00:00 2001
From: Ondrej Mirtes <ondrej@mirtes.cz>
Date: Sat, 8 Jan 2022 21:57:40 +0100
Subject: [PATCH] PDO::prepare returns BenevolentUnionType

---
 conf/config.neon                              |  5 +++
 .../PdoPrepareDynamicReturnTypeExtension.php  | 37 +++++++++++++++++++
 .../Analyser/NodeScopeResolverTest.php        |  1 +
 tests/PHPStan/Analyser/data/pdo-prepare.php   | 17 +++++++++
 4 files changed, 60 insertions(+)
 create mode 100644 src/Type/Php/PdoPrepareDynamicReturnTypeExtension.php
 create mode 100644 tests/PHPStan/Analyser/data/pdo-prepare.php

diff --git a/conf/config.neon b/conf/config.neon
index 0e051152fe..a7325cb18c 100644
--- a/conf/config.neon
+++ b/conf/config.neon
@@ -1144,6 +1144,11 @@ services:
 		tags:
 			- phpstan.dynamicFunctionThrowTypeExtension
 
+	-
+		class: PHPStan\Type\Php\PdoPrepareDynamicReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicMethodReturnTypeExtension
+
 	-
 		class: PHPStan\Type\Php\ReflectionClassConstructorThrowTypeExtension
 		tags:
diff --git a/src/Type/Php/PdoPrepareDynamicReturnTypeExtension.php b/src/Type/Php/PdoPrepareDynamicReturnTypeExtension.php
new file mode 100644
index 0000000000..e5d417ad49
--- /dev/null
+++ b/src/Type/Php/PdoPrepareDynamicReturnTypeExtension.php
@@ -0,0 +1,37 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Php;
+
+use PhpParser\Node\Expr\MethodCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\MethodReflection;
+use PHPStan\Reflection\ParametersAcceptorSelector;
+use PHPStan\Type\DynamicMethodReturnTypeExtension;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeUtils;
+
+class PdoPrepareDynamicReturnTypeExtension implements DynamicMethodReturnTypeExtension
+{
+
+	public function getClass(): string
+	{
+		return 'PDO';
+	}
+
+	public function isMethodSupported(MethodReflection $methodReflection): bool
+	{
+		return $methodReflection->getName() === 'prepare';
+	}
+
+	public function getTypeFromMethodCall(MethodReflection $methodReflection, MethodCall $methodCall, Scope $scope): Type
+	{
+		$returnType = ParametersAcceptorSelector::selectFromArgs(
+			$scope,
+			$methodCall->getArgs(),
+			$methodReflection->getVariants(),
+		)->getReturnType();
+
+		return TypeUtils::toBenevolentUnion($returnType);
+	}
+
+}
diff --git a/tests/PHPStan/Analyser/NodeScopeResolverTest.php b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
index 77101cf375..be41d9ea00 100644
--- a/tests/PHPStan/Analyser/NodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
@@ -594,6 +594,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/classPhpDocs-phpstanPropertyPrefix.php');
 
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/array-destructuring-types.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/pdo-prepare.php');
 	}
 
 	/**
diff --git a/tests/PHPStan/Analyser/data/pdo-prepare.php b/tests/PHPStan/Analyser/data/pdo-prepare.php
new file mode 100644
index 0000000000..72c4ab39c6
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/pdo-prepare.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace PDOPrepare;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+
+	public function doFoo()
+	{
+		$database = new \PDO('dsn');
+		$logDeleteQuery = $database->prepare('DELETE FROM log');
+		assertType('(PDOStatement|false)', $logDeleteQuery);
+	}
+
+}