Open Radar

 
Summary:
I think this might be related to some issues I’ve been seeing where SourceKitService crashes hard any time I look at the Either.swift file in my project. Box is being imported from a separate module but SourceKitService may not know that, and thus it implodes.


Steps to Reproduce:
1. Try to compile this:

enum E {
	case C(Box<Int>)

	var c: Box<Int>? {
		switch self {
		case let C(c): return c
		}
	}
}


Expected Results:
I expected it to error on the use of undeclared type 'Box', but not to crash.


Actual Results:
It printed errors about the use of the undeclared type 'Box', and then it crashed.


Regression:
Using Array<Int> instead of Box<Int> does not crash. Providing a definition of Box does not crash.


Notes:
Encountered this while pursuing a workaround to rdar://19673469 — which may or may not be related.