Sema: Allow @available on stored properties as long as its as new as the deployment target

Author: slavapestov

lib/Sema/TypeCheckAttr.cpp

@@ -1471,12 +1471,6 @@ void AttributeChecker::visitAvailableAttr(AvailableAttr *attr) {
 
   SourceLoc attrLoc = attr->getLocation();
 
-  Optional<Diag<>> MaybeNotAllowed =
-      TypeChecker::diagnosticIfDeclCannotBePotentiallyUnavailable(D);
-  if (MaybeNotAllowed.hasValue()) {
-    diagnose(attrLoc, MaybeNotAllowed.getValue());
-  }
-
   // Find the innermost enclosing declaration with an availability
   // range annotation and ensure that this attribute's available version range
   // is fully contained within that declaration's range. If there is no such
@@ -1494,16 +1488,27 @@ void AttributeChecker::visitAvailableAttr(AvailableAttr *attr) {
     EnclosingDecl = getEnclosingDeclForDecl(EnclosingDecl);
   }
 
-  if (!EnclosingDecl)
-    return;
-
   AvailabilityContext AttrRange{
       VersionRange::allGTE(attr->Introduced.getValue())};
 
-  if (!AttrRange.isContainedIn(EnclosingAnnotatedRange.getValue())) {
-    diagnose(attr->getLocation(), diag::availability_decl_more_than_enclosing);
-    diagnose(EnclosingDecl->getLoc(),
-             diag::availability_decl_more_than_enclosing_enclosing_here);
+  if (EnclosingDecl) {
+    if (!AttrRange.isContainedIn(EnclosingAnnotatedRange.getValue())) {
+      diagnose(attr->getLocation(), diag::availability_decl_more_than_enclosing);
+      diagnose(EnclosingDecl->getLoc(),
+               diag::availability_decl_more_than_enclosing_enclosing_here);
+    }
+  }
+
+  Optional<Diag<>> MaybeNotAllowed =
+      TypeChecker::diagnosticIfDeclCannotBePotentiallyUnavailable(D);
+  if (MaybeNotAllowed.hasValue()) {
+    AvailabilityContext DeploymentRange
+        = AvailabilityContext::forDeploymentTarget(Ctx);
+    if (EnclosingAnnotatedRange.hasValue())
+      DeploymentRange.intersectWith(*EnclosingAnnotatedRange);
+
+    if (!DeploymentRange.isContainedIn(AttrRange))
+      diagnose(attrLoc, MaybeNotAllowed.getValue());
   }
 }
 

test/Sema/availability_stored.swift

@@ -0,0 +1,34 @@
+// RUN: %target-typecheck-verify-swift
+
+// Code should type check with a new enough deployment target:
+// RUN: %target-swift-frontend -typecheck %s -target x86_64-apple-macos50
+
+// REQUIRES: OS=macosx
+
+@available(macOS 50, *)
+struct NewStruct {}
+
+@available(macOS 50, *)
+struct GoodReference {
+  var x: NewStruct
+}
+
+@available(macOS 50, *)
+struct GoodNestedReference {
+  struct Inner {
+    var x: NewStruct
+  }
+}
+
+struct BadReference1 {
+  // expected-error@+1 {{stored properties cannot be marked potentially unavailable with '@available'}}
+  @available(macOS 50, *)
+  var x: NewStruct
+}
+
+@available(macOS 40, *)
+struct BadReference2 {
+  // expected-error@+1 {{stored properties cannot be marked potentially unavailable with '@available'}}
+  @available(macOS 50, *)
+  var x: NewStruct
+}

test/Sema/availability_versions.swift

@@ -309,7 +309,6 @@ class SubOfClassWithUnavailableInitializer : SuperWithWithUnavailableInitializer
 class ClassWithUnavailableProperties {
     // expected-note@-1 4{{add @available attribute to enclosing class}}
 
-  @available(OSX, introduced: 10.9) // expected-error {{stored properties cannot be marked potentially unavailable with '@available'}}
   var nonLazyAvailableOn10_9Stored: Int = 9
 
   @available(OSX, introduced: 10.51) // expected-error {{stored properties cannot be marked potentially unavailable with '@available'}}