Sema: Members with availability in unavailable containers should be unavailable

lib/Sema/TypeCheckAvailability.cpp

@@ -333,6 +333,30 @@ static bool computeContainedByDeploymentTarget(TypeRefinementContext *TRC,
                   .isContainedIn(AvailabilityContext::forDeploymentTarget(ctx));
 }
 
+/// Returns true if the reference or any of its parents is an
+/// unconditional unavailable declaration for the same platform.
+static bool isInsideCompatibleUnavailableDeclaration(
+    const Decl *D, const ExportContext &where, const AvailableAttr *attr) {
+  auto referencedPlatform = where.getUnavailablePlatformKind();
+  if (!referencedPlatform)
+    return false;
+
+  if (!attr->isUnconditionallyUnavailable()) {
+    return false;
+  }
+
+  // Refuse calling unavailable functions from unavailable code,
+  // but allow the use of types.
+  PlatformKind platform = attr->Platform;
+  if (platform == PlatformKind::none && !isa<TypeDecl>(D) &&
+      !isa<ExtensionDecl>(D)) {
+    return false;
+  }
+
+  return (*referencedPlatform == platform ||
+          inheritsAvailabilityFromPlatform(platform, *referencedPlatform));
+}
+
 namespace {
 
 /// A class to walk the AST to build the type refinement context hierarchy.
@@ -1191,6 +1215,12 @@ bool TypeChecker::isDeclarationUnavailable(
 Optional<UnavailabilityReason>
 TypeChecker::checkDeclarationAvailability(const Decl *D,
                                           const ExportContext &Where) {
+  // Skip computing potential unavailability if the declaration is explicitly
+  // unavailable and the context is also unavailable.
+  if (const AvailableAttr *Attr = AvailableAttr::isUnavailable(D))
+    if (isInsideCompatibleUnavailableDeclaration(D, Where, Attr))
+      return None;
+
   if (isDeclarationUnavailable(D, Where.getDeclContext(), [&Where] {
         return Where.getAvailabilityContext();
       })) {
@@ -2013,33 +2043,6 @@ const AvailableAttr *TypeChecker::getDeprecated(const Decl *D) {
   return nullptr;
 }
 
-/// Returns true if the reference or any of its parents is an
-/// unconditional unavailable declaration for the same platform.
-static bool isInsideCompatibleUnavailableDeclaration(
-    const Decl *D, const ExportContext &where,
-    const AvailableAttr *attr) {
-  auto referencedPlatform = where.getUnavailablePlatformKind();
-  if (!referencedPlatform)
-    return false;
-
-  if (!attr->isUnconditionallyUnavailable()) {
-    return false;
-  }
-
-  // Refuse calling unavailable functions from unavailable code,
-  // but allow the use of types.
-  PlatformKind platform = attr->Platform;
-  if (platform == PlatformKind::none &&
-      !isa<TypeDecl>(D) &&
-      !isa<ExtensionDecl>(D)) {
-    return false;
-  }
-
-  return (*referencedPlatform == platform ||
-          inheritsAvailabilityFromPlatform(platform,
-                                           *referencedPlatform));
-}
-
 static void fixItAvailableAttrRename(InFlightDiagnostic &diag,
                                      SourceRange referenceRange,
                                      const ValueDecl *renamedDecl,

test/Sema/availability_versions.swift

@@ -1632,10 +1632,6 @@ func funcWithMultipleShortFormAnnotationsForTheSamePlatform() {
       // expected-note@-1 {{add 'if #available' version check}}
 }
 
-@available(OSX 10.9, *)
-@available(OSX, unavailable)
-func unavailableWins() { } // expected-note {{'unavailableWins()' has been explicitly marked unavailable here}}
-
 func useShortFormAvailable() {
   // expected-note@-1 4{{add @available attribute to enclosing global function}}
 
@@ -1654,6 +1650,34 @@ func useShortFormAvailable() {
 
   funcWithMultipleShortFormAnnotationsForTheSamePlatform() // expected-error {{'funcWithMultipleShortFormAnnotationsForTheSamePlatform()' is only available in macOS 10.53 or newer}}
       // expected-note@-1 {{add 'if #available' version check}}
+}
+
+// Unavailability takes precedence over availability and is inherited
+
+@available(OSX 10.9, *)
+@available(OSX, unavailable)
+func unavailableWins() { }
+    // expected-note@-1 {{'unavailableWins()' has been explicitly marked unavailable here}}
+
+struct HasUnavailableExtension {
+  @available(OSX, unavailable)
+  public func directlyUnavailable() { }
+      // expected-note@-1 {{'directlyUnavailable()' has been explicitly marked unavailable here}}
+}
+
+@available(OSX, unavailable)
+extension HasUnavailableExtension {
+  public func inheritsUnavailable() { }
+      // expected-note@-1 {{'inheritsUnavailable()' has been explicitly marked unavailable here}}
+
+  @available(OSX 10.9, *)
+  public func moreAvailableButStillUnavailable() { }
+      // expected-note@-1 {{'moreAvailableButStillUnavailable()' has been explicitly marked unavailable here}}
+}
 
+func useHasUnavailableExtension(_ s: HasUnavailableExtension) {
   unavailableWins() // expected-error {{'unavailableWins()' is unavailable}}
+  s.directlyUnavailable() // expected-error {{'directlyUnavailable()' is unavailable}}
+  s.inheritsUnavailable() // expected-error {{'inheritsUnavailable()' is unavailable in macOS}}
+  s.moreAvailableButStillUnavailable() // expected-error {{'moreAvailableButStillUnavailable()' is unavailable in macOS}}
 }

test/attr/attr_availability_transitive_osx.swift

@@ -106,7 +106,39 @@ extension Outer {
 
 @available(OSX, unavailable)
 extension Outer {
+  // expected-note@+1 {{'outer_osx_init_osx' has been explicitly marked unavailable here}}
   static var outer_osx_init_osx = osx() // OK
+
+  // expected-note@+1 {{'osx_call_osx()' has been explicitly marked unavailable here}}
+  func osx_call_osx() {
+    osx() // OK
+  }
+
+  func osx_call_osx_extension() {
+    osx_extension() // OK; osx_extension is only unavailable if -application-extension is passed.
+  }
+
+  func takes_and_returns_osx(_ x: NotOnOSX) -> NotOnOSX {
+    return x // OK
+  }
+
+  // This @available should be ignored; inherited unavailability takes precedence
+  @available(OSX 999, *)
+  // expected-note@+1 {{'osx_more_available_but_still_unavailable_call_osx()' has been explicitly marked unavailable here}}
+  func osx_more_available_but_still_unavailable_call_osx() {
+    osx() // OK
+  }
+
+  // rdar://92551870
+  func osx_call_osx_more_available_but_still_unavailable() {
+    osx_more_available_but_still_unavailable_call_osx() // OK
+  }
+}
+
+func takesOuter(_ o: Outer) {
+  _ = Outer.outer_osx_init_osx // expected-error {{'outer_osx_init_osx' is unavailable in macOS}}
+  o.osx_call_osx() // expected-error {{'osx_call_osx()' is unavailable in macOS}}
+  o.osx_more_available_but_still_unavailable_call_osx() // expected-error {{'osx_more_available_but_still_unavailable_call_osx()' is unavailable in macOS}}
 }
 
 @available(OSX, unavailable)