left-associative ternary operator

[azjezz]

Hack seems to follow PHP in this unusual behavior, but since PHP 5.x support is gone, its time to fix this.

Similar to what @[nikic] proposed for PHP 7.4, the type checker HHVM can force using parentheses with nested ternary operations, and a change can be made in the future to make the ternary operation right-associative.

links :

• https://bugs.php.net/bug.php?id=61915
• https://externals.io/message/105163
• https://wiki.php.net/rfc/ternary_associativity

---

HHVM Version

➜  framework git:(http) ✗ hhvm --version
HipHop VM 4.1.0 (rel)
Compiler: 1555455032_861766839
Repo schema: b1f582ab39dca7cf649292454f7b664970bf83d9
➜  framework git:(http) ✗ hh_client --version
hh-21577913b41b950cbe2cd887f46cb30964e59cbd-4.1.0 Tue Apr 16 23:55:04 2019
➜  framework git:(http) ✗ 

Operating System and Version

irrelevant

Standalone code, or other way to reproduce the problem

<<__EntryPoint>>
function main(): void {
	$order = "3";
	$food = ($order == '1') ? 'Banana' :
	        ($order == '2') ? 'Apple' :
	        ($order == '3') ? 'Toast' :
	        ($order == '4') ? 'Cantalope' :
	        ($order == '5') ? 'Swiss Cheese' : 'Fig Newton Cookie';

	print $food . "\n";
}

Actual result

Swiss Cheese

Expected result

Toast

[lexidor]

This is a very sensible thing to do. All existing Hack code is indifferent to the associativity of the ternary operator. (A typecheck bans the behavior.) It would be nice to "fix" this.