support deprecated magic __toString() in echo statement

rules.neon

@@ -1,6 +1,8 @@
 services:
     -
         class: PHPStan\Rules\Deprecations\DeprecatedClassHelper
+    -
+        class: PHPStan\Rules\Deprecations\EchoDeprecatedBinaryOpToStringRule
 
 rules:
 	- PHPStan\Rules\Deprecations\AccessDeprecatedPropertyRule
@@ -19,3 +21,7 @@ rules:
 	- PHPStan\Rules\Deprecations\TypeHintDeprecatedInFunctionSignatureRule
 	- PHPStan\Rules\Deprecations\UsageOfDeprecatedCastRule
 	- PHPStan\Rules\Deprecations\UsageOfDeprecatedTraitRule
+
+conditionalTags:
+	PHPStan\Rules\Deprecations\EchoDeprecatedBinaryOpToStringRule:
+		phpstan.rules.rule: %featureToggles.bleedingEdge%

src/Rules/Deprecations/EchoDeprecatedBinaryOpToStringRule.php

@@ -0,0 +1,88 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Deprecations;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr\BinaryOp;
+use PHPStan\Analyser\Scope;
+use PHPStan\Broker\Broker;
+use PHPStan\Type\TypeUtils;
+
+/**
+ * @implements \PHPStan\Rules\Rule<BinaryOp>
+ */
+class EchoDeprecatedBinaryOpToStringRule implements \PHPStan\Rules\Rule
+{
+
+	/** @var Broker */
+	private $broker;
+
+	public function __construct(Broker $broker)
+	{
+		$this->broker = $broker;
+	}
+
+	public function getNodeType(): string
+	{
+		return BinaryOp::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if (DeprecatedScopeHelper::isScopeDeprecated($scope)) {
+			return [];
+		}
+
+		$messages = [];
+		$message = $this->checkExpr($node->left, $scope);
+		if ($message) {
+			$messages[] = $message;
+		}
+		$message = $this->checkExpr($node->right, $scope);
+		if ($message) {
+			$messages[] = $message;
+		}
+
+		return $messages;
+	}
+
+	private function checkExpr(Node\Expr $node, Scope $scope): ?string
+	{
+		$methodCalledOnType = $scope->getType($node);
+		$referencedClasses = TypeUtils::getDirectClassNames($methodCalledOnType);
+
+		foreach ($referencedClasses as $referencedClass) {
+			try {
+				$classReflection = $this->broker->getClass($referencedClass);
+				$methodReflection = $classReflection->getNativeMethod('__toString');
+
+				if (!$methodReflection->isDeprecated()->yes()) {
+					return null;
+				}
+
+				$description = $methodReflection->getDeprecatedDescription();
+				if ($description === null) {
+					return sprintf(
+						'Call to deprecated method %s() of class %s.',
+						$methodReflection->getName(),
+						$methodReflection->getDeclaringClass()->getName()
+					);
+				}
+
+				return sprintf(
+					"Call to deprecated method %s() of class %s:\n%s",
+					$methodReflection->getName(),
+					$methodReflection->getDeclaringClass()->getName(),
+					$description
+				);
+			} catch (\PHPStan\Broker\ClassNotFoundException $e) {
+				// Other rules will notify if the class is not found
+			} catch (\PHPStan\Reflection\MissingMethodFromReflectionException $e) {
+				// Other rules will notify if the the method is not found
+			}
+		}
+
+		return null;
+	}
+
+}

src/Rules/Deprecations/EchoDeprecatedToStringRule.php

@@ -0,0 +1,115 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Deprecations;
+
+use PhpParser\Node;
+use PhpParser\Node\Stmt\Echo_;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\RuleLevelHelper;
+use PHPStan\Type\ErrorType;
+use PHPStan\Type\ObjectType;
+use PHPStan\Type\Type;
+
+/**
+ * @implements \PHPStan\Rules\Rule<Echo_>
+ */
+class EchoDeprecatedToStringRule implements \PHPStan\Rules\Rule
+{
+
+	/** @var RuleLevelHelper */
+	private $ruleLevelHelper;
+
+	public function __construct(RuleLevelHelper $ruleLevelHelper)
+	{
+		$this->ruleLevelHelper = $ruleLevelHelper;
+	}
+
+	public function getNodeType(): string
+	{
+		return Echo_::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if (DeprecatedScopeHelper::isScopeDeprecated($scope)) {
+			return [];
+		}
+
+		$messages = [];
+		foreach ($node->exprs as $key => $expr) {
+			$this->deepCheckExpr($expr, $scope, $messages);
+		}
+
+		return $messages;
+	}
+
+	/**
+	 * @param Node\Expr $expr
+	 * @param Scope $scope
+	 * @param string[] $messages
+	 */
+	private function deepCheckExpr(Node\Expr $expr, Scope $scope, array &$messages): void
+	{
+		if ($expr instanceof Node\Expr\BinaryOp) {
+			$this->deepCheckExpr($expr->left, $scope, $messages);
+			$this->deepCheckExpr($expr->right, $scope, $messages);
+		} elseif ($expr instanceof Node\Expr\Cast\String_ || $expr instanceof Node\Expr\Assign || $expr instanceof Node\Expr\AssignOp) {
+			$this->deepCheckExpr($expr->expr, $scope, $messages);
+		} elseif ($expr instanceof Node\Scalar\Encapsed) {
+			foreach ($expr->parts as $part) {
+				$this->deepCheckExpr($part, $scope, $messages);
+			}
+		} else {
+			$message = $this->checkExpr($expr, $scope);
+
+			if ($message) {
+				$messages[] = $message;
+			}
+		}
+	}
+
+	private function checkExpr(Node\Expr $expr, Scope $scope): ?string
+	{
+		$type = $this->ruleLevelHelper->findTypeToCheck(
+			$scope,
+			$expr,
+			'',
+			static function (Type $type): bool {
+				return !$type->toString() instanceof ErrorType;
+			}
+		)->getType();
+
+		if (!$type instanceof ObjectType) {
+			return null;
+		}
+
+		$classReflection = $type->getClassReflection();
+
+		if ($classReflection === null) {
+			return null;
+		}
+
+		$methodReflection = $classReflection->getNativeMethod('__toString');
+
+		if (!$methodReflection->isDeprecated()->yes()) {
+			return null;
+		}
+
+		$description = $methodReflection->getDeprecatedDescription();
+		if ($description === null) {
+			return sprintf(
+				'Call to deprecated method %s() of class %s.',
+				$methodReflection->getName(),
+				$methodReflection->getDeclaringClass()->getName()
+			);
+		}
+
+		return sprintf(
+			"Call to deprecated method %s() of class %s:\n%s",
+			$methodReflection->getName(),
+			$methodReflection->getDeclaringClass()->getName(),
+			$description
+		);
+	}
+
+}

tests/Rules/Deprecations/EchoDeprecatedBinaryOpToStringRuleTest.php

@@ -0,0 +1,66 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Deprecations;
+
+/**
+ * @extends \PHPStan\Testing\RuleTestCase<EchoDeprecatedBinaryOpToStringRule>
+ */
+class EchoDeprecatedBinaryOpToStringRuleTest extends \PHPStan\Testing\RuleTestCase
+{
+
+	protected function getRule(): \PHPStan\Rules\Rule
+	{
+		return new EchoDeprecatedBinaryOpToStringRule($this->createBroker());
+	}
+
+	public function testDeprecatedMagicMethodToStringCall(): void
+	{
+		require_once __DIR__ . '/data/echo-deprecated-binaryop-magic-method-tostring.php';
+		$this->analyse(
+			[__DIR__ . '/data/echo-deprecated-binaryop-magic-method-tostring.php'],
+			[
+				[
+					'Call to deprecated method __toString() of class EchoDeprecatedBinaryOpToStringRule\MagicBar.',
+					8,
+				],
+				[
+					'Call to deprecated method __toString() of class EchoDeprecatedBinaryOpToStringRule\MagicBar.',
+					9,
+				],
+				[
+					'Call to deprecated method __toString() of class EchoDeprecatedBinaryOpToStringRule\MagicBar.',
+					10,
+				],
+				[
+					'Call to deprecated method __toString() of class EchoDeprecatedBinaryOpToStringRule\MagicBar.',
+					11,
+				],
+				[
+					'Call to deprecated method __toString() of class EchoDeprecatedBinaryOpToStringRule\MagicBar.',
+					12,
+				],
+				[
+					"Call to deprecated method __toString() of class EchoDeprecatedBinaryOpToStringRule\MagicBarWithDesc:\nuse XY instead.",
+					15,
+				],
+				[
+					"Call to deprecated method __toString() of class EchoDeprecatedBinaryOpToStringRule\MagicBarWithDesc:\nuse XY instead.",
+					16,
+				],
+				[
+					"Call to deprecated method __toString() of class EchoDeprecatedBinaryOpToStringRule\MagicBarWithDesc:\nuse XY instead.",
+					17,
+				],
+				[
+					"Call to deprecated method __toString() of class EchoDeprecatedBinaryOpToStringRule\MagicBarWithDesc:\nuse XY instead.",
+					18,
+				],
+				[
+					"Call to deprecated method __toString() of class EchoDeprecatedBinaryOpToStringRule\MagicBarWithDesc:\nuse XY instead.",
+					19,
+				],
+			]
+		);
+	}
+
+}