Nowadays, PHP’s typehinting has matured greatly and earned its slot in PHP coder’s tool belt.
It is now facing the eternal challenge of catching up with legacy code. Those were built
without type checks, leading to explicit enforcement and wide-ranging arguments usage.
Moreover, an average PHP application has thousands of methods to checks, and even more arguments,
returntype and properties to review. Yet, even without support from the old PHP versions, type hinting was already underlying a good number of coding structures, which are both detectable and safe to update. Scalars are the first step, followed by tightening checks and code simplifications. The most advanced tools both look for those, and PR them directly for mass updates. There is always help
on the road to typehinting. This leaves you the actual conception of a safe type system.