My thoughts overall on this: 0. I'm not against introducing the attribute, only how it's used/enforced etc. (And, incidentally, what it actually MEANS, see if you can spot that from the rest of my comments....)
1. Static analysers and IDEs: I agree with everyone who's said that whether or not the return value is "used" should be a concern for tooling like static analysers and the IDE, and ideally not for PHP runtime. Attributes were added as a structured replacement for docblock props and I don't like it when they affect how a program actually runs (as long as you're not using reflection). 2. If it must be a concern for PHP at runtime, a warning is preferred over an exception. It only makes sense – it's in the name: Exceptions are for exceptional situations, warnings are for warning you. 3. Naming of the attribute: I think the most precise name (if I understand the purpose correctly) is: #[ReturnValueMayContainCriticalInformation] 4. Should all internal functions, such as fopen() (which may return false on error instead of throwing an exception), have this attribute? I understand that ideally we only want to add it where the failure to inspect the return value could result in something outright dangerous, but I think that's a really hard call to make. If we scale it back to mean "Look, this function may not behave the way you'd expect it to, - the return value may actually contain some information you might be interested in, so you better check it man", then I think it could be a small but useful addition. Best, Jakob
