Only force immediate closure of an open existential when we opened one.

Fixes rdar://problem/21597711.

Swift SVN r30190

Author: DougGregor

lib/Sema/CSApply.cpp

@@ -956,7 +956,7 @@ namespace {
 
         ref->setType(refType);
 
-        closeExistential(ref, /*force=*/true);
+        closeExistential(ref, /*force=*/openedExistential);
 
         return ref;
       }
@@ -997,7 +997,7 @@ namespace {
         // Reference to an unbound instance method.
         Expr *result = new (context) DotSyntaxBaseIgnoredExpr(base, dotLoc,
                                                               ref);
-        closeExistential(result, /*force=*/true);
+        closeExistential(result, /*force=*/openedExistential);
         return result;
       } else {
         assert((!baseIsInstance || member->isInstanceMember()) &&

test/Constraints/existential_metatypes.swift

@@ -71,3 +71,17 @@ extension P2 {
 func testP2(pt: P2.Type) {
   pt.init().elements
 }
+
+// rdar://problem/21597711
+protocol P3 {
+  func withP3(fn: (P3) -> ())
+}
+
+class Something {
+  func takeP3(p: P3) { }
+}
+
+
+func testP3(p: P3, something: Something) {
+  p.withP3(Something.takeP3(something))
+}