[hl] Comparing null to 0

[RealyUniqueName]

class Main {
	static function main() {
		function check(?i:Int) {
			trace(i == 0); // false
			trace(i < 0);  // false
			trace(i > 0);  // false
			trace(i <= 0); // true
			trace(i >= 0); // true
		}
		check();
	}
}

[ncannasse]

Uhm. Seems like there is a null-to-int cast being done here.

[Simn]

genhl just determines a common type between the operands and then casts both to that type. This is fine for most cases but breaks semantics when Null<T> gets involved because we don't want to unwrap.

[Simn]

Also I'm mildly shocked that our tests don't cover this.

[Simn]

This is pretty much superseded by #8426, but I just 4.1ed that due to gencommon cancer. Feel free to 4.1 or close this one as well if you don't want to look into it for HL at the moment.

[RealyUniqueName]

I'm closing this because it's a part of #8426 indeed.