User:Legoktm/0

Goal: submit an RFC asking for removal of this special case. '0' instead is truthy, while empty string is still falsey.

Tim says it should be fine to add a deprecation warning there.

Are there any other languages where '0' is falsey?

Perl also treats the string "0" as false. The exact string "0 but true" is used as an alternative by some builtin functions for returning true-valued numeric zeros, and is special-cased to not generate runtime warnings about non-numeric strings undergoing numeric conversions.
Tcl, as a stringly typed language, also treats the string "0" as false.

Would you want this feature in PHP today (without thinking about backwards-compatibility)?

Why did PHP introduce this behavior in the first place?

Can static linters stop this? E.g. phan, psalm? Why is that insufficient?

Examples of gotchas by experienced PHP programmers: