SIL: Update verifier's isLoweringOf check for lowered Optionals.

Optional now lowers its payload type, and we lower away the Optional/IUO distinction in SIL's type system, but the verifier was not updated to account for this.

Author: jckarter

lib/SIL/SILVerifier.cpp

@@ -1578,26 +1578,22 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
   // Is a SIL type a potential lowering of a formal type?
   static bool isLoweringOf(SILType loweredType,
                            CanType formalType) {
+    
+    
     // Dynamic self has the same lowering as its contained type.
     if (auto dynamicSelf = dyn_cast<DynamicSelfType>(formalType))
       formalType = CanType(dynamicSelf->getSelfType());
 
-    // Optional of dynamic self has the same lowering as its contained type.
-    OptionalTypeKind loweredOptionalKind;
-    OptionalTypeKind formalOptionalKind;
-
-    CanType loweredObjectType = loweredType.getSwiftRValueType()
-        .getAnyOptionalObjectType(loweredOptionalKind);
+    // Optional lowers its contained type. The difference between Optional
+    // and IUO is lowered away.
+    SILType loweredObjectType = loweredType
+        .getAnyOptionalObjectType();
     CanType formalObjectType = formalType
-        .getAnyOptionalObjectType(formalOptionalKind);
+        .getAnyOptionalObjectType();
 
-    if (loweredOptionalKind != OTK_None) {
-      if (auto dynamicSelf = dyn_cast<DynamicSelfType>(formalObjectType)) {
-        formalObjectType = dynamicSelf->getSelfType()->getCanonicalType();
-      }
-      return loweredOptionalKind == formalOptionalKind &&
-             isLoweringOf(SILType::getPrimitiveAddressType(loweredObjectType),
-                          formalObjectType);
+    if (loweredObjectType) {
+      return formalObjectType &&
+             isLoweringOf(loweredObjectType, formalObjectType);
     }
 
     // Metatypes preserve their instance type through lowering.

test/SILGen/dynamic_lookup.swift

@@ -270,3 +270,16 @@ func downcast(_ obj: AnyObject) -> X {
 func consume(_ fruit: Fruit) {
   _ = fruit.juice
 }
+
+// rdar://problem/29249513 -- looking up an IUO member through AnyObject
+// produces a Foo!? type. The SIL verifier did not correctly consider Optional
+// to be the lowering of IUO (which is now eliminated by SIL lowering).
+
+@objc protocol IUORequirement {
+  var iuoProperty: AnyObject! { get }
+}
+
+func getIUOPropertyDynamically(x: AnyObject) -> Any {
+  return x.iuoProperty
+}
+