rector/rules/DeadCode/Rector/Stmt/RemoveUnreachableStatementRector.php

<?php

declare(strict_types=1);

namespace Rector\DeadCode\Rector\Stmt;

use PhpParser\Node;
use PhpParser\Node\Expr\Exit_;
use PhpParser\Node\Expr\MethodCall;
use PhpParser\Node\Expr\StaticCall;
use PhpParser\Node\FunctionLike;
use PhpParser\Node\Stmt;
use PhpParser\Node\Stmt\Else_;
use PhpParser\Node\Stmt\Expression;
use PhpParser\Node\Stmt\Foreach_;
use PhpParser\Node\Stmt\If_;
use PhpParser\Node\Stmt\Nop;
use PhpParser\Node\Stmt\Return_;
use PhpParser\Node\Stmt\Throw_;
use Rector\Core\Rector\AbstractRector;
use Rector\DeadCode\SideEffect\SideEffectNodeDetector;
use Rector\NodeTypeResolver\Node\AttributeKey;
use Symplify\RuleDocGenerator\ValueObject\CodeSample\CodeSample;
use Symplify\RuleDocGenerator\ValueObject\RuleDefinition;

/**
 * @changelog https://github.com/phpstan/phpstan/blob/83078fe308a383c618b8c1caec299e5765d9ac82/src/Node/UnreachableStatementNode.php
 *
 * @see \Rector\Tests\DeadCode\Rector\Stmt\RemoveUnreachableStatementRector\RemoveUnreachableStatementRectorTest
 */
final class RemoveUnreachableStatementRector extends AbstractRector
{
    public function __construct(private readonly SideEffectNodeDetector $sideEffectNodeDetector)
    {
    }

    public function getRuleDefinition(): RuleDefinition
    {
        return new RuleDefinition('Remove unreachable statements', [
            new CodeSample(
                <<<'CODE_SAMPLE'
class SomeClass
{
    public function run()
    {
        return 5;

        $removeMe = 10;
    }
}
CODE_SAMPLE
                ,
                <<<'CODE_SAMPLE'
class SomeClass
{
    public function run()
    {
        return 5;
    }
}
CODE_SAMPLE
            ),
        ]);
    }

    /**
     * @return array<class-string<Node>>
     */
    public function getNodeTypes(): array
    {
        return [Foreach_::class, FunctionLike::class, Else_::class, If_::class];
    }

    /**
     * @param Foreach_|FunctionLike|Else_|If_ $node
     */
    public function refactor(Node $node): ?Node
    {
        $stmts = $node->stmts;

        $isPassedTheUnreachable = false;
        $toBeRemovedKeys = [];

        foreach ($stmts as $key => $stmt) {
            if ($this->shouldSkipNode($stmt)) {
                continue;
            }

            if ($this->isUnreachable($stmt)) {
                $isPassedTheUnreachable = true;
            }

            if ($this->isAfterMarkTestSkippedMethodCall($stmt)) {
                // keep for test case temporary ignored
                break;
            }

            if (! $isPassedTheUnreachable) {
                continue;
            }

            $toBeRemovedKeys[] = $key;
        }

        if ($toBeRemovedKeys === []) {
            return null;
        }

        $start = reset($toBeRemovedKeys);
        if (! isset($stmts[$start - 1])) {
            return null;
        }

        $previousFirstUnreachable = $stmts[$start - 1];
        if (in_array($previousFirstUnreachable::class, [Throw_::class, Return_::class, Exit_::class], true)) {
            return $this->processCleanUpUnreachabelStmts($node, $toBeRemovedKeys);
        }

        // check previous side effect can check against start jump key - 2
        // as previously already checked as reachable part
        if (! $this->hasPreviousSideEffect($start - 2, $stmts)) {
            return $this->processCleanUpUnreachabelStmts($node, $toBeRemovedKeys);
        }

        return null;
    }

    /**
     * @param Stmt[] $stmts
     */
    private function hasPreviousSideEffect(int $start, array $stmts): bool
    {
        for ($key = $start; $key > 0; --$key) {
            $previousStmt = $stmts[$key];
            $hasSideEffect = (bool) $this->betterNodeFinder->findFirst(
                $previousStmt,
                fn (Node $node): bool => $this->sideEffectNodeDetector->detectCallExpr($node)
            );

            if ($hasSideEffect) {
                return true;
            }
        }

        return false;
    }

    /**
     * @param int[] $toBeRemovedKeys
     */
    private function processCleanUpUnreachabelStmts(Foreach_|FunctionLike|Else_|If_ $node, array $toBeRemovedKeys): Node
    {
        foreach ($toBeRemovedKeys as $toBeRemovedKey) {
            unset($node->stmts[$toBeRemovedKey]);
        }

        return $node;
    }

    private function shouldSkipNode(Stmt $stmt): bool
    {
        return $stmt instanceof Nop;
    }

    private function isUnreachable(Stmt $stmt): bool
    {
        $isUnreachable = $stmt->getAttribute(AttributeKey::IS_UNREACHABLE);

        return $isUnreachable === true;
    }

    /**
     * Keep content after markTestSkipped(), intentional temporary
     */
    private function isAfterMarkTestSkippedMethodCall(Stmt $stmt): bool
    {
        if (! $stmt instanceof Expression) {
            return false;
        }

        $expr = $stmt->expr;
        if ($expr instanceof MethodCall || $expr instanceof StaticCall) {
            return $this->isNames($expr->name, ['markTestSkipped', 'markTestIncomplete']);
        }

        return false;
    }
}