Merge pull request #27642 from DougGregor/property-wrappers-di-access

Author: swift-ci

lib/SILGen/SILGenLValue.cpp

@@ -1366,19 +1366,30 @@ namespace {
                                  std::move(value), isSelfParameter);
     }
 
+    /// Determine whether the backing variable for the given
+    /// property (that has a wrapper) is visible from the
+    /// current context.
+    static bool isBackingVarVisible(VarDecl *field,
+                                    DeclContext *fromDC){
+      VarDecl *backingVar = field->getPropertyWrapperBackingProperty();
+      return backingVar->isAccessibleFrom(fromDC);
+    }
+
     void set(SILGenFunction &SGF, SILLocation loc,
              ArgumentSource &&value, ManagedValue base) && override {
       assert(getAccessorDecl()->isSetter());
       SILDeclRef setter = Accessor;
 
-      if (hasPropertyWrapper() && IsOnSelfParameter) {
+      if (hasPropertyWrapper() && IsOnSelfParameter &&
+          isBackingVarVisible(cast<VarDecl>(Storage),
+                              SGF.FunctionDC)) {
         // This is wrapped property. Instead of emitting a setter, emit an
         // assign_by_wrapper with the allocating initializer function and the
         // setter function as arguments. DefiniteInitializtion will then decide
         // between the two functions, depending if it's an initialization or a
         // re-assignment.
         //
-        VarDecl *field = dyn_cast<VarDecl>(Storage);
+        VarDecl *field = cast<VarDecl>(Storage);
         VarDecl *backingVar = field->getPropertyWrapperBackingProperty();
         assert(backingVar);
         CanType ValType =

test/SILGen/Inputs/property_wrapper_defs.swift

@@ -16,3 +16,7 @@ public struct MyPublished<Value> {
 		set { self = newValue }
 	}
 }
+
+public class UsesMyPublished {
+  @MyPublished public var foo: Int = 17
+}

test/SILGen/property_wrappers.swift

@@ -508,6 +508,17 @@ open class TestMyWrapper {
   @MyWrapper open var useMyWrapper: Int? = nil
 }
 
+// rdar://problem/54352235 - crash due to reference to private backing var
+extension UsesMyPublished {
+  // CHECK-LABEL: sil hidden [ossa] @$s21property_wrapper_defs15UsesMyPublishedC0A9_wrappersE6setFooyySiF : $@convention(method) (Int, @guaranteed UsesMyPublished) -> ()
+  // CHECK: class_method %1 : $UsesMyPublished, #UsesMyPublished.foo!setter.1
+  // CHECK-NOT: assign_by_wrapper
+  // CHECK: return
+  func setFoo(_ x: Int) {
+    foo = x
+  }
+}
+
 // CHECK-LABEL: sil_vtable ClassUsingWrapper {
 // CHECK-NEXT:  #ClassUsingWrapper.x!getter.1: (ClassUsingWrapper) -> () -> Int : @$s17property_wrappers17ClassUsingWrapperC1xSivg   // ClassUsingWrapper.x.getter
 // CHECK-NEXT:  #ClassUsingWrapper.x!setter.1: (ClassUsingWrapper) -> (Int) -> () : @$s17property_wrappers17ClassUsingWrapperC1xSivs // ClassUsingWrapper.x.setter