[SE-0258] Fix memberwise initializer involving wrapped properties.

The determination of which type to use within the implicit memberwise
initializer for a wrapper property (between the original property type
and the wrapper type) could be affected by the synthesis of the call
to the default initializer. Rewrite the logic here to depend on
aspects of the AST that don't change with further type checking.

Author: DougGregor

lib/AST/Decl.cpp

@@ -5475,21 +5475,33 @@ bool VarDecl::isPropertyWrapperInitializedWithInitialValue() const {
   if (!ctx.getLazyResolver())
     return false;
 
-  // If there is no initializer, the initialization form depends on
-  // whether the property wrapper type has an init(initialValue:).
-  if (!isParentInitialized()) {
-    // If it's default-initializable, that doesn't use an initial value.
-    if (auto *PBD = getParentPatternBinding())
-      if (PBD->isDefaultInitializable())
-        return false;
+  auto customAttr = getAttachedPropertyWrapper();
+  if (!customAttr)
+    return false;
 
-    auto wrapperTypeInfo = getAttachedPropertyWrapperTypeInfo();
-    return wrapperTypeInfo.initialValueInit != nullptr;
-  }
+  auto *PBD = getParentPatternBinding();
+  if (!PBD)
+    return false;
+
+  // If there was an initializer on the original property, initialize
+  // via the initial value.
+  if (PBD->getPatternList()[0].getEqualLoc().isValid())
+    return true;
+
+  // If there was an initializer on the attribute itself, initialize
+  // via the full wrapper.
+  if (customAttr->getArg() != nullptr)
+    return false;
 
-  // Otherwise, check whether the '=' initialization form was used.
-  return getPropertyWrapperBackingPropertyInfo().originalInitialValue
-      != nullptr;
+  // If the property wrapper is default-initializable, it's the wrapper
+  // being initialized.
+  if (PBD->isDefaultInitializable(0))
+    return false;
+
+  // There is no initializer, so the initialization form depends on
+  // whether the property wrapper type has an init(initialValue:).
+  auto wrapperTypeInfo = getAttachedPropertyWrapperTypeInfo();
+  return wrapperTypeInfo.initialValueInit != nullptr;
 }
 
 Identifier VarDecl::getObjCPropertyName() const {

test/IDE/print_property_wrappers.swift

@@ -47,7 +47,7 @@ struct HasWrappers {
   var z: String
 
   // Memberwise initializer.
-  // CHECK: init(x: Wrapper<Int> = Wrapper(closure: foo), y: Bool = true, z: String = Wrapper())
+  // CHECK: init(x: Wrapper<Int> = Wrapper(closure: foo), y: Bool = true, z: Wrapper<String> = Wrapper())
 }
 
 func trigger() {