[Sema] Emit an error for attempts to use @available on var declarations that have attached property wrappers. Availability is not supported on stored properties, and properties with property wrappers are stored properties with a layer of indirection. Also, add the same missing diagnostic for lazy vars.

Resolves rdar://82713248

Author: tshortli

include/swift/AST/Decl.h

@@ -5390,6 +5390,10 @@ class VarDecl : public AbstractStorageDecl {
   /// an attached property wrapper.
   VarDecl *getPropertyWrapperWrappedValueVar() const;
 
+  /// Return true if this property either has storage or has an attached property
+  /// wrapper that has storage.
+  bool hasStorageOrWrapsStorage() const;
+  
   /// Visit all auxiliary declarations to this VarDecl.
   ///
   /// An auxiliary declaration is a declaration synthesized by the compiler to support

lib/AST/Decl.cpp

@@ -6446,6 +6446,20 @@ VarDecl *VarDecl::getPropertyWrapperWrappedValueVar() const {
   return getPropertyWrapperAuxiliaryVariables().localWrappedValueVar;
 }
 
+bool VarDecl::hasStorageOrWrapsStorage() const {
+  if (hasStorage())
+    return true;
+  
+  if (getAttrs().hasAttribute<LazyAttr>())
+    return true;
+  
+  auto *backing = getPropertyWrapperBackingProperty();
+  if (backing && backing->hasStorage())
+    return true;
+  
+  return false;
+}
+
 void VarDecl::visitAuxiliaryDecls(llvm::function_ref<void(VarDecl *)> visit) const {
   if (getDeclContext()->isTypeContext() || isImplicit())
     return;

lib/Sema/CodeSynthesis.cpp

@@ -928,10 +928,7 @@ bool AreAllStoredPropertiesDefaultInitableRequest::evaluate(
           if (VD->getAttrs().hasAttribute<NSManagedAttr>())
             CheckDefaultInitializer = false;
 
-          if (VD->hasStorage())
-            HasStorage = true;
-          auto *backing = VD->getPropertyWrapperBackingProperty();
-          if (backing && backing->hasStorage())
+          if (VD->hasStorageOrWrapsStorage())
             HasStorage = true;
         });
 

lib/Sema/TypeCheckAttr.cpp

@@ -3562,7 +3562,7 @@ TypeChecker::diagnosticIfDeclCannotBePotentiallyUnavailable(const Decl *D) {
   auto *DC = D->getDeclContext();
 
   if (auto *VD = dyn_cast<VarDecl>(D)) {
-    if (!VD->hasStorage())
+    if (!VD->hasStorageOrWrapsStorage())
       return None;
 
     // Do not permit potential availability of script-mode global variables;

test/Sema/availability_stored.swift

@@ -8,29 +8,55 @@
 @available(macOS 50, *)
 struct NewStruct {}
 
+@available(macOS 50, *)
+@propertyWrapper
+struct NewPropertyWrapper<Value> {
+  var wrappedValue: Value
+}
+
 @available(macOS 50, *)
 struct GoodReferenceStruct {
   var x: NewStruct
+  @NewPropertyWrapper var y: Int
+  lazy var z: Int = 42
 }
 
 @available(macOS 50, *)
 struct GoodNestedReferenceStruct {
   struct Inner {
     var x: NewStruct
+    @NewPropertyWrapper var y: Int
+    lazy var z: Int = 42
   }
 }
 
 struct BadReferenceStruct1 {
   // expected-error@+1 {{stored properties cannot be marked potentially unavailable with '@available'}}
   @available(macOS 50, *)
   var x: NewStruct
+  
+  // expected-error@+1 {{stored properties cannot be marked potentially unavailable with '@available'}}
+  @available(macOS 50, *)
+  @NewPropertyWrapper var y: Int
+  
+  // expected-error@+1 {{stored properties cannot be marked potentially unavailable with '@available'}}
+  @available(macOS 50, *)
+  lazy var z: Int = 42
 }
 
 @available(macOS 40, *)
 struct BadReferenceStruct2 {
   // expected-error@+1 {{stored properties cannot be marked potentially unavailable with '@available'}}
   @available(macOS 50, *)
   var x: NewStruct
+  
+  // expected-error@+1 {{stored properties cannot be marked potentially unavailable with '@available'}}
+  @available(macOS 50, *)
+  @NewPropertyWrapper var y: Int
+  
+  // expected-error@+1 {{stored properties cannot be marked potentially unavailable with '@available'}}
+  @available(macOS 50, *)
+  lazy var z: Int = 42
 }
 
 // The same behavior should hold for enum elements with payloads.

test/decl/class/effectful_properties.swift

@@ -86,6 +86,7 @@ class AcceptableDynamic {
 }
 
 // mainly just some sanity checks
+// expected-error@+1 {{class 'Misc' has no initializers}}
 class Misc {
   // expected-error@+2 {{'lazy' cannot be used on a computed property}}
   // expected-error@+1 {{lazy properties must have an initializer}}