[CSSolver] NFC: Add few more tests to verify () -> T to () -> Void conversions

(cherry picked from commit 2646258)

Author: xedin

test/Constraints/closures.swift

@@ -652,15 +652,37 @@ func rdar36054961() {
   }])
 }
 
+protocol P_37790062 {
+  associatedtype T
+  var elt: T { get }
+}
+
 func rdar37790062() {
   struct S<T> {
     init(_ a: () -> T, _ b: () -> T) {}
   }
 
+  class C1 : P_37790062 {
+    typealias T = Int
+    var elt: T { return 42 }
+  }
+
+  class C2 : P_37790062 {
+    typealias T = (String, Int, Void)
+    var elt: T { return ("question", 42, ()) }
+  }
+
   func foo() -> Int { return 42 }
   func bar() -> Void {}
   func baz() -> (String, Int) { return ("question", 42) }
+  func bzz<T>(_ a: T) -> T { return a }
+  func faz<T: P_37790062>(_ a: T) -> T.T { return a.elt }
 
   _ = S({ foo() }, { bar() }) // Ok, should infer T to be 'Void'
   _ = S({ baz() }, { bar() }) // Ok, should infer T to be 'Void'
+  _ = S({ bzz(("question", 42)) }, { bar() }) // Ok
+  _ = S({ bzz(String.self) }, { bar() }) // Ok
+  _ = S({ bzz(((), (()))) }, { bar() }) // Ok
+  _ = S({ bzz(C1()) }, { bar() }) // Ok
+  _ = S({ faz(C2()) }, { bar() }) // Ok
 }