Sema: Always allow method overrides to be as available as the context

lib/Sema/TypeCheckAvailability.cpp

@@ -1575,6 +1575,12 @@ TypeChecker::availabilityAtLocation(SourceLoc loc, const DeclContext *DC,
   return availability;
 }
 
+AvailabilityContext
+TypeChecker::availabilityForDeclSignature(const Decl *decl) {
+  return TypeChecker::availabilityAtLocation(decl->getLoc(),
+                                             decl->getInnermostDeclContext());
+}
+
 AvailabilityRange TypeChecker::overApproximateAvailabilityAtLocation(
     SourceLoc loc, const DeclContext *DC,
     const AvailabilityScope **MostRefined) {

lib/Sema/TypeCheckDeclOverride.cpp

@@ -1817,10 +1817,10 @@ static bool isAvailabilitySafeForOverride(ValueDecl *override,
 
   // Allow overrides that are not as available as the base decl as long as the
   // override is as available as its context.
-  auto overrideTypeAvailability = AvailabilityInference::availableRange(
+  auto availabilityContext = TypeChecker::availabilityForDeclSignature(
       override->getDeclContext()->getSelfNominalTypeDecl());
 
-  return overrideTypeAvailability.isContainedIn(overrideInfo);
+  return availabilityContext.getPlatformRange().isContainedIn(overrideInfo);
 }
 
 /// Returns true if a diagnostic about an accessor being less available

lib/Sema/TypeChecker.h

@@ -1011,6 +1011,9 @@ AvailabilityContext
 availabilityAtLocation(SourceLoc loc, const DeclContext *DC,
                        const AvailabilityScope **MostRefined = nullptr);
 
+/// Returns the availability context of the signature of the given declaration.
+AvailabilityContext availabilityForDeclSignature(const Decl *decl);
+
 /// Returns an over-approximation of the range of operating system versions
 /// that could the passed-in location could be executing upon for
 /// the target platform. If MostRefined != nullptr, set to the most-refined

test/Sema/availability_versions.swift

@@ -238,7 +238,7 @@ protocol BaseProto {
 
   var property: A { get set } // expected-note {{overridden declaration is here}}
 
-  @available(OSX 10.51, *)
+  @available(OSX 51, *)
   var newProperty: A { get set } // expected-note {{overridden declaration is here}}
 
   func method() // expected-note {{overridden declaration is here}}
@@ -247,24 +247,24 @@ protocol BaseProto {
 protocol RefinesBaseProto_AsAvailableOverrides: BaseProto {
   var property: A { get set }
 
-  @available(OSX 10.51, *)
+  @available(OSX 51, *)
   var newProperty: A { get set }
 
   func method()
 }
 
 protocol RefinesBaseProto_LessAvailableOverrides: BaseProto {
-  @available(OSX 10.52, *)
+  @available(OSX 52, *)
   var property: A { get set } // expected-error {{overriding 'property' must be as available as declaration it overrides}}
 
-  @available(OSX 10.52, *)
+  @available(OSX 52, *)
   var newProperty: A { get set } // expected-error {{overriding 'newProperty' must be as available as declaration it overrides}}
 
-  @available(OSX 10.52, *)
+  @available(OSX 52, *)
   func method()  // expected-error {{overriding 'method' must be as available as declaration it overrides}}
 }
 
-@available(OSX 10.52, *)
+@available(OSX 52, *)
 protocol RefinesBaseProto_LessAvailable: BaseProto {
   var property: A { get set }
   var newProperty: A { get set }
@@ -892,6 +892,57 @@ class SubWithLimitedMemberAvailability : SuperWithAlwaysAvailableMembers {
   }
 }
 
+extension ClassAvailableOn10_9 {
+  class NestedSubWithLimitedMemberAvailability: SuperWithAlwaysAvailableMembers {
+    @available(OSX, introduced: 10.9)
+    override func shouldAlwaysBeAvailableMethod() {}
+
+    @available(OSX, introduced: 10.9)
+    override var shouldAlwaysBeAvailableProperty: Int {
+      get { return 10 }
+      set(newVal) {}
+    }
+
+    override var setterShouldAlwaysBeAvailableProperty: Int {
+      get { return 9 }
+      @available(OSX, introduced: 10.9)
+      set(newVal) {}
+    }
+
+    override var getterShouldAlwaysBeAvailableProperty: Int {
+      @available(OSX, introduced: 10.9)
+      get { return 9 }
+      set(newVal) {}
+    }
+  }
+}
+
+@available(OSX, introduced: 51)
+extension ClassAvailableOn51 {
+  class NestedSubWithLimitedMemberAvailability: SuperWithAlwaysAvailableMembers {
+    @available(OSX, introduced: 51)
+    override func shouldAlwaysBeAvailableMethod() {}
+
+    @available(OSX, introduced: 51)
+    override var shouldAlwaysBeAvailableProperty: Int {
+      get { return 10 }
+      set(newVal) {}
+    }
+
+    override var setterShouldAlwaysBeAvailableProperty: Int {
+      get { return 9 }
+      @available(OSX, introduced: 51)
+      set(newVal) {}
+    }
+
+    override var getterShouldAlwaysBeAvailableProperty: Int {
+      @available(OSX, introduced: 51)
+      get { return 9 }
+      set(newVal) {}
+    }
+  }
+}
+
 @available(OSX, introduced: 51)
 class SubWithLimitedAvailablility : SuperWithAlwaysAvailableMembers {
   override func shouldAlwaysBeAvailableMethod() {}

test/attr/attr_inlinable_available.swift

@@ -1690,3 +1690,170 @@ public enum UnavailableEnumWithClasses {
   public class InheritsAfterDeploymentTarget: AfterDeploymentTargetClass {}
   public class InheritsUnavailable: UnavailableClass {}
 }
+
+// MARK: - Overrides
+
+public class Base {
+  @available(macOS 10.9, *)
+  public func beforeInliningTargetMethod() {} // expected-note 3 {{overridden declaration is here}}
+
+  @available(macOS 10.10, *)
+  public func atInliningTargetMethod() {}// expected-note 3 {{overridden declaration is here}}
+
+  @available(macOS 10.14.5, *)
+  public func betweenTargetsMethod() {}// expected-note 3 {{overridden declaration is here}}
+
+  @available(macOS 10.15, *)
+  public func atDeploymentTargetMethod() {}// expected-note 2 {{overridden declaration is here}}
+
+  @available(macOS 11, *)
+  public func afterDeploymentTargetMethod() {}// expected-note {{overridden declaration is here}}
+}
+
+public class DerivedNoAvailable: Base {
+  public override func beforeInliningTargetMethod() {}
+  public override func atInliningTargetMethod() {}
+  public override func betweenTargetsMethod() {}
+  public override func atDeploymentTargetMethod() {}
+  public override func afterDeploymentTargetMethod() {}
+}
+
+@available(macOS 10.9, *)
+public class DerivedBeforeInliningTarget: Base {
+  @available(macOS 10.9, *)
+  public override func beforeInliningTargetMethod() {}
+  @available(macOS 10.9, *)
+  public override func atInliningTargetMethod() {}
+  @available(macOS 10.9, *)
+  public override func betweenTargetsMethod() {}
+  @available(macOS 10.9, *)
+  public override func atDeploymentTargetMethod() {}
+  @available(macOS 10.9, *)
+  public override func afterDeploymentTargetMethod() {}
+}
+
+@available(macOS 10.10, *)
+public class DerivedAtInliningTarget: Base {
+  @available(macOS 10.10, *)
+  public override func beforeInliningTargetMethod() {}
+  @available(macOS 10.10, *)
+  public override func atInliningTargetMethod() {}
+  @available(macOS 10.10, *)
+  public override func betweenTargetsMethod() {}
+  @available(macOS 10.10, *)
+  public override func atDeploymentTargetMethod() {}
+  @available(macOS 10.10, *)
+  public override func afterDeploymentTargetMethod() {}
+}
+
+@available(macOS 10.14.5, *)
+public class DerivedBetweenTargets: Base {
+  @available(macOS 10.14.5, *)
+  public override func beforeInliningTargetMethod() {}
+  @available(macOS 10.14.5, *)
+  public override func atInliningTargetMethod() {}
+  @available(macOS 10.14.5, *)
+  public override func betweenTargetsMethod() {}
+  @available(macOS 10.14.5, *)
+  public override func atDeploymentTargetMethod() {}
+  @available(macOS 10.14.5, *)
+  public override func afterDeploymentTargetMethod() {}
+}
+
+@available(macOS 10.15, *)
+public class DerivedAtDeploymentTarget: Base {
+  @available(macOS 10.15, *)
+  public override func beforeInliningTargetMethod() {}
+  @available(macOS 10.15, *)
+  public override func atInliningTargetMethod() {}
+  @available(macOS 10.15, *)
+  public override func betweenTargetsMethod() {}
+  @available(macOS 10.15, *)
+  public override func atDeploymentTargetMethod() {}
+  @available(macOS 10.15, *)
+  public override func afterDeploymentTargetMethod() {}
+}
+
+@available(macOS 11, *)
+public class DerivedAfterDeploymentTarget: Base {
+  @available(macOS 11, *)
+  public override func beforeInliningTargetMethod() {}
+  @available(macOS 11, *)
+  public override func atInliningTargetMethod() {}
+  @available(macOS 11, *)
+  public override func betweenTargetsMethod() {}
+  @available(macOS 11, *)
+  public override func atDeploymentTargetMethod() {}
+  @available(macOS 11, *)
+  public override func afterDeploymentTargetMethod() {}
+}
+
+public class DerivedAtDeploymentTargetOverrides: Base {
+  @available(macOS 10.15, *)
+  public override func beforeInliningTargetMethod() {} // expected-error {{overriding 'beforeInliningTargetMethod' must be as available as declaration it overrides}}
+
+  @available(macOS 10.15, *)
+  public override func atInliningTargetMethod() {} // expected-error {{overriding 'atInliningTargetMethod' must be as available as declaration it overrides}}
+
+  @available(macOS 10.15, *)
+  public override func betweenTargetsMethod() {} // expected-error {{overriding 'betweenTargetsMethod' must be as available as declaration it overrides}}
+
+  @available(macOS 10.15, *)
+  public override func atDeploymentTargetMethod() {}
+
+  @available(macOS 10.15, *)
+  public override func afterDeploymentTargetMethod() {}
+}
+
+public class DerivedFutureOverrides: Base {
+  @available(macOS 12, *)
+  public override func beforeInliningTargetMethod() {} // expected-error {{overriding 'beforeInliningTargetMethod' must be as available as declaration it overrides}}
+
+  @available(macOS 12, *)
+  public override func atInliningTargetMethod() {} // expected-error {{overriding 'atInliningTargetMethod' must be as available as declaration it overrides}}
+
+  @available(macOS 12, *)
+  public override func betweenTargetsMethod() {} // expected-error {{overriding 'betweenTargetsMethod' must be as available as declaration it overrides}}
+
+  @available(macOS 12, *)
+  public override func atDeploymentTargetMethod() {} // expected-error {{overriding 'atDeploymentTargetMethod' must be as available as declaration it overrides}}
+
+  @available(macOS 12, *)
+  public override func afterDeploymentTargetMethod() {} // expected-error {{overriding 'afterDeploymentTargetMethod' must be as available as declaration it overrides}}
+}
+
+extension AtDeploymentTarget {
+  public class DerivedAtDeploymentTargetOverrides: Base {
+    @available(macOS 10.15, *)
+    public override func beforeInliningTargetMethod() {}
+
+    @available(macOS 10.15, *)
+    public override func atInliningTargetMethod() {}
+
+    @available(macOS 10.15, *)
+    public override func betweenTargetsMethod() {}
+
+    @available(macOS 10.15, *)
+    public override func atDeploymentTargetMethod() {}
+
+    @available(macOS 10.15, *)
+    public override func afterDeploymentTargetMethod() {}
+  }
+
+  public class DerivedAfterDeploymentTargetOverrides: Base {
+    @available(macOS 11, *)
+    public override func beforeInliningTargetMethod() {} // expected-error {{overriding 'beforeInliningTargetMethod' must be as available as declaration it overrides}}
+
+    @available(macOS 11, *)
+    public override func atInliningTargetMethod() {} // expected-error {{overriding 'atInliningTargetMethod' must be as available as declaration it overrides}}
+
+    @available(macOS 11, *)
+    public override func betweenTargetsMethod() {} // expected-error {{overriding 'betweenTargetsMethod' must be as available as declaration it overrides}}
+
+    @available(macOS 11, *)
+    public override func atDeploymentTargetMethod() {} // expected-error {{overriding 'atDeploymentTargetMethod' must be as available as declaration it overrides}}
+
+    @available(macOS 11, *)
+    public override func afterDeploymentTargetMethod() {}
+  }
+}