[RFC] Support for <func>::function syntax

Hello internals, Looking for feedback on the idea of supporting ::function syntax (or ::fn) for consistency with existing ::class syntax: $arr = ['apple']; print_r(array_map(strtoupper::function, $arr)); (Apologies if this has already been discussed. Hard to search for colon-colon-function.) Benefits in my view are readability and potential use in static analysis. Downsides (as implemented in proof-of-concept) are that it can be needlessly littered in a lot of places, and that it breaks class consts named function. I'd vote against it in its current state, but if people like the general idea maybe the drawbacks can be addressed with a better implementation. Examples: https://gist.github.com/adsr/2c0b9243986418af3cecf8046657304b Proof-of-concept: https://github.com/adsr/php-src/commit/07bb24243022ccef5823f6977d231f3535a48a07.patch Adam