Report functions and methods that unconditionally call themselves on every code path

src/Rules/Functions/InfiniteFunctionRecursionRule.php

@@ -0,0 +1,81 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Functions;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr;
+use PhpParser\Node\Expr\FuncCall;
+use PhpParser\Node\Name;
+use PHPStan\Analyser\Scope;
+use PHPStan\DependencyInjection\RegisteredRule;
+use PHPStan\Node\FunctionReturnStatementsNode;
+use PHPStan\Reflection\ReflectionProvider;
+use PHPStan\Rules\InfiniteRecursionFinder;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+use function sprintf;
+use function strtolower;
+
+/**
+ * @implements Rule<FunctionReturnStatementsNode>
+ */
+#[RegisteredRule(level: 4)]
+final class InfiniteFunctionRecursionRule implements Rule
+{
+
+	public function __construct(
+		private InfiniteRecursionFinder $finder,
+		private ReflectionProvider $reflectionProvider,
+	)
+	{
+	}
+
+	public function getNodeType(): string
+	{
+		return FunctionReturnStatementsNode::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if ($node->isGenerator()) {
+			return [];
+		}
+
+		$function = $node->getFunctionReflection();
+		$functionName = strtolower($function->getName());
+		$reflectionProvider = $this->reflectionProvider;
+
+		$isSelfCall = static function (Expr $expr) use ($functionName, $reflectionProvider, $scope): bool {
+			if (!$expr instanceof FuncCall) {
+				return false;
+			}
+			if ($expr->isFirstClassCallable()) {
+				return false;
+			}
+			if (!$expr->name instanceof Name) {
+				return false;
+			}
+			if (!$reflectionProvider->hasFunction($expr->name, $scope)) {
+				return false;
+			}
+
+			return strtolower($reflectionProvider->getFunction($expr->name, $scope)->getName()) === $functionName;
+		};
+
+		$call = $this->finder->find($node->getStatements(), $isSelfCall);
+		if ($call === null) {
+			return [];
+		}
+
+		return [
+			RuleErrorBuilder::message(sprintf(
+				'Function %s() calls itself on every code path, leading to infinite recursion.',
+				$function->getName(),
+			))
+				->identifier('function.infiniteRecursion')
+				->line($call->getStartLine())
+				->build(),
+		];
+	}
+
+}