What are the potential risks or drawbacks of modifying the PHP source code?

Modifying the PHP source code can introduce potential risks such as breaking existing functionality, causing unexpected behavior, or making the codebase difficult to maintain. It is generally recommended to avoid modifying the core PHP source code and instead utilize best practices like creating custom functions, classes, or plugins to extend functionality.

// Avoid modifying the core PHP source code
// Instead, create custom functions or classes to extend functionality