Popular Static Code Analysis Tools for PHP with Examples

Static code analysis tools are invaluable for developers as they automatically scan your codebase to identify potential security vulnerabilities, coding errors, and style inconsistencies. Here’s a look at three popular options for PHP with code samples, outputs, and explanations:

1. PHP CodeSniffer

• Focus: Primarily enforces coding standards and best practices.
• Sample Code:

<?php
function greet($name) {
  echo "Hello, $name!"; // Missing curly braces around the echo statement
}

greet("World");
?>

• Sample Output:

FILE: example.php
  1. ERROR  Squiz.ControlStructures.ControlSignature.MissingCurlyBrace after if, elseif, foreach, for or while statement  []

• Explanation: PHP CodeSniffer identifies the missing curly braces after the echo statement within the greet function, which is a violation of coding standards and can lead to unexpected behavior.

2. PHPStan

• Focus: Primarily identifies potential runtime errors and security vulnerabilities.
• Sample Code:

function divide($a, $b) {
  if ($b === 0) {
    throw new Exception("Division by zero"); // Potential division by zero error
  }
  return $a / $b;
}

$result = divide(10, 0);

• Sample Output:

example.php:10: Uncaught exception 'Exception' with message 'Division by zero' (most likely cause: divide($a, $b))

• Explanation: PHPStan detects the potential division by zero error in the divide function and warns you about the uncaught exception.

3. Scrutinizer

• Focus: Comprehensive analysis covering code quality, security, and potential bugs.
• Sample Code:

$user_input = $_GET['username'];
$sanitized_username = htmlspecialchars($user_input); // Potential XSS vulnerability

echo "Welcome, $sanitized_username!";

• Sample Output (may vary depending on configuration):

example.php:5  Potential XSS vulnerability  Medium

This code snippet uses htmlspecialchars to sanitize user input, but it might 
not be sufficient to prevent all XSS attacks. Consider using a more robust 
sanitization library or escaping mechanisms depending on the context.

• Explanation: Scrutinizer identifies the potential XSS vulnerability because htmlspecialchars might not always prevent malicious scripts from being injected into the output. It suggests exploring alternative sanitization methods for enhanced security.

Choosing the Right Tool:

The best tool for you depends on your specific needs. PHP CodeSniffer is excellent for enforcing coding standards. PHPStan excels at identifying runtime errors. Scrutinizer provides a comprehensive analysis covering various aspects. Consider combining these tools or using one that aligns best with your project’s requirements.