Open Radar

 
Summary:
’Twas the night before Christmas
when all through the house
the compiler exploded
and crashed with a flounce


Steps to Reproduce:
1. Compile this:
func ignore<T>(parser: String -> (T, String)?) -> String -> ((), String)? {
	return { parser($0).map { _ in () } }
}
func | <T> (left: String -> (T, String)?, right: String -> ((), String)?) -> String -> (T?, String)? {
	return { _ in nil }
}

ignore(" " | "\r" | "\t" | "\n")


Expected Results:
I expected it to error out on the final line, which is ill-typed.


Actual Results:
Crash.


Regression:
The workaround in this case is to write correct code.
It doesn’t crash if you remove `ignore` on the final line (leaving only the parens & their contents).
It doesn’t crash with <4 strings. It does crash with >= 4 strings. There’s a Holy Hand Grenade joke to be made here but I can’t be arsed.


Notes:
N/A