AST: Improved inferred availability accuracy.

Previously, when creating availability attributes for synthesized declarations we would identify some set of reference declarations that the synthesized declaration should be as-available-as. The availability attributes of the reference declarations would then be merged together to create the attributes for the synthesized declaration. The problem with this approach is that the reference declarations themselves may implicitly inherit availability from their enclosing scopes, so the resulting merged attributes could be incomplete. The fix is to walk though the enclosing scopes of the reference declarations, merging the availability attributes found at each level.

Additionally, the merging algorithm that produces inferred availability attributes failed to deal with conflicts between platform specific and platform agnostic availability. Now the merging algorithm notices when platform agnostic availability should take precedence and avoids generating conflicting platform specific attributes.

Resolves rdar://106575142

Author: tshortli

lib/AST/Availability.cpp

@@ -143,26 +143,54 @@ void AvailabilityInference::applyInferredAvailableAttrs(
   // a per-platform basis.
   std::map<PlatformKind, InferredAvailability> Inferred;
   for (const Decl *D : InferredFromDecls) {
-    for (const DeclAttribute *Attr : D->getAttrs()) {
-      auto *AvAttr = dyn_cast<AvailableAttr>(Attr);
-      if (!AvAttr || AvAttr->isInvalid())
-        continue;
+    do {
+      for (const DeclAttribute *Attr : D->getAttrs()) {
+        auto *AvAttr = dyn_cast<AvailableAttr>(Attr);
+        if (!AvAttr || AvAttr->isInvalid())
+          continue;
 
-      mergeWithInferredAvailability(AvAttr, Inferred[AvAttr->Platform]);
+        mergeWithInferredAvailability(AvAttr, Inferred[AvAttr->Platform]);
 
-      if (Message.empty() && !AvAttr->Message.empty())
-        Message = AvAttr->Message;
+        if (Message.empty() && !AvAttr->Message.empty())
+          Message = AvAttr->Message;
 
-      if (Rename.empty() && !AvAttr->Rename.empty()) {
-        Rename = AvAttr->Rename;
-        RenameDecl = AvAttr->RenameDecl;
+        if (Rename.empty() && !AvAttr->Rename.empty()) {
+          Rename = AvAttr->Rename;
+          RenameDecl = AvAttr->RenameDecl;
+        }
       }
+
+      // Walk up the enclosing declaration hierarchy to make sure we aren't
+      // missing any inherited attributes.
+      D = AvailabilityInference::parentDeclForInferredAvailability(D);
+    } while (D);
+  }
+
+  DeclAttributes &Attrs = ToDecl->getAttrs();
+
+  // Some kinds of platform agnostic availability supersede any platform
+  // specific availability.
+  auto InferredAgnostic = Inferred.find(PlatformKind::none);
+  if (InferredAgnostic != Inferred.end()) {
+    switch (InferredAgnostic->second.PlatformAgnostic) {
+    case PlatformAgnosticAvailabilityKind::Deprecated:
+    case PlatformAgnosticAvailabilityKind::UnavailableInSwift:
+    case PlatformAgnosticAvailabilityKind::Unavailable:
+      Attrs.add(createAvailableAttr(PlatformKind::none,
+                                    InferredAgnostic->second, Message, Rename,
+                                    RenameDecl, Context));
+      return;
+
+    case PlatformAgnosticAvailabilityKind::None:
+    case PlatformAgnosticAvailabilityKind::SwiftVersionSpecific:
+    case PlatformAgnosticAvailabilityKind::PackageDescriptionVersionSpecific:
+    case PlatformAgnosticAvailabilityKind::NoAsync:
+      break;
     }
   }
 
   // Create an availability attribute for each observed platform and add
   // to ToDecl.
-  DeclAttributes &Attrs = ToDecl->getAttrs();
   for (auto &Pair : Inferred) {
     auto *Attr = createAvailableAttr(Pair.first, Pair.second, Message,
                                      Rename, RenameDecl, Context);

test/ModuleInterface/actor_availability.swift

@@ -65,4 +65,16 @@ extension Enum {
     // CHECK-NEXT:   get
     // CHECK-NEXT: }
   }
+
+  // CHECK: #if compiler(>=5.3) && $Actors
+  // CHECK-NEXT: @_hasMissingDesignatedInitializers @available(macOS, unavailable)
+  // CHECK-NEXT: public actor UnavailableExtensionNestedActor {
+  @available(macOS, unavailable)
+  public actor UnavailableExtensionNestedActor {
+    // CHECK: @available(iOS 13.4, tvOS 13.4, watchOS 6.2, *)
+    // CHECK-NEXT: @available(macOS, unavailable)
+    // CHECK-NEXT: @_semantics("defaultActor") nonisolated final public var unownedExecutor: _Concurrency.UnownedSerialExecutor {
+    // CHECK-NEXT:   get
+    // CHECK-NEXT: }
+  }
 }

test/Sema/generalized_accessors_availability.swift

@@ -37,6 +37,40 @@ struct ModifyConditionallyAvailable<T> {
     }
 }
 
+@propertyWrapper
+struct SetterMoreAvailable<T> {
+    var wrappedValue: T {
+        get { fatalError() }
+
+        @available(macOS 10.49, *)
+        set { fatalError() }
+    }
+
+    var projectedValue: T {
+        get { fatalError() }
+
+        @available(macOS 10.49, *)
+        set { fatalError() }
+    }
+}
+
+@propertyWrapper
+struct ModifyMoreAvailable<T> {
+    var wrappedValue: T {
+        get { fatalError() }
+
+        @available(macOS 10.49, *)
+        _modify { fatalError() }
+    }
+
+    var projectedValue: T {
+        get { fatalError() }
+
+        @available(macOS 10.49, *)
+        _modify { fatalError() }
+    }
+}
+
 struct Butt {
     var modify_conditionally_available: Int {
         get { fatalError() }
@@ -50,6 +84,12 @@ struct Butt {
 
     @ModifyConditionallyAvailable
     var wrapped_modify_conditionally_available: Int
+
+    @SetterMoreAvailable
+    var wrapped_setter_more_available: Int
+
+    @ModifyMoreAvailable
+    var wrapped_modify_more_available: Int
 }
 
 func butt(x: inout Butt) { // expected-note * {{}}
@@ -58,6 +98,10 @@ func butt(x: inout Butt) { // expected-note * {{}}
     x.wrapped_modify_conditionally_available = 0 // expected-error {{only available in macOS 10.51 or newer}} expected-note{{}}
     x.$wrapped_setter_conditionally_available = 0 // expected-error {{only available in macOS 10.51 or newer}} expected-note{{}}
     x.$wrapped_modify_conditionally_available = 0 // expected-error {{only available in macOS 10.51 or newer}} expected-note{{}}
+    x.wrapped_setter_more_available = 0
+    x.wrapped_modify_more_available = 0
+    x.$wrapped_setter_more_available = 0
+    x.$wrapped_modify_more_available = 0
 
     if #available(macOS 10.51, *) {
         x.modify_conditionally_available = 0
@@ -68,6 +112,25 @@ func butt(x: inout Butt) { // expected-note * {{}}
     }
 }
 
+@available(macOS, unavailable)
+extension Butt {
+  @available(iOS, unavailable)
+  struct Nested { // expected-note {{has been explicitly marked unavailable here}}
+    @SetterMoreAvailable
+    var wrapped_setter_more_available: Int // expected-note 2 {{has been explicitly marked unavailable here}}
+
+    @ModifyMoreAvailable
+    var wrapped_modify_more_available: Int // expected-note 2 {{has been explicitly marked unavailable here}}
+  }
+}
+
+func testButtNested(x: inout Butt.Nested) { // expected-error {{'Nested' is unavailable in macOS}}
+  x.wrapped_setter_more_available = 0 // expected-error {{is unavailable in macOS}}
+  x.wrapped_modify_more_available = 0 // expected-error {{is unavailable in macOS}}
+  x.$wrapped_setter_more_available = 0 // expected-error {{is unavailable in macOS}}
+  x.$wrapped_modify_more_available = 0 // expected-error {{is unavailable in macOS}}
+}
+
 @available(macOS 11.0, *)
 struct LessAvailable {
   @SetterConditionallyAvailable

validation-test/Sema/SwiftUI/rdar106575142.swift

@@ -0,0 +1,33 @@
+// RUN: %target-typecheck-verify-swift -target %target-cpu-apple-macosx12 -swift-version 5
+
+// REQUIRES: objc_interop
+// REQUIRES: OS=macosx
+
+import SwiftUI
+
+@available(macOS 12, *)
+struct S {}
+
+@available(iOS, unavailable)
+extension S {
+  class NestedOtherPlatformUnavailable {
+    @Published var x: Int = 0
+    @Binding var y: Bool
+
+    init(y: Binding<Bool>) {
+      _y = y
+    }
+  }
+}
+
+@available(*, unavailable)
+extension S {
+  class NestedAlwaysUnavailable {
+    @Published var x: Int = 0
+    @Binding var y: Bool
+
+    init(y: Binding<Bool>) {
+      _y = y
+    }
+  }
+}