Enable availability attributes for associated types

include/swift/AST/Attr.def

@@ -108,7 +108,7 @@ DECL_ATTR(_silgen_name, SILGenName,
   OnAbstractFunction | OnVar | LongAttribute | UserInaccessible | ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove,
   0)
 DECL_ATTR(available, Available,
-  OnAbstractFunction | OnGenericType | OnVar | OnSubscript | OnEnumElement | OnMacro | OnExtension | AllowMultipleAttributes | LongAttribute | ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove,
+  OnAbstractFunction | OnAssociatedType | OnGenericType | OnVar | OnSubscript | OnEnumElement | OnMacro | OnExtension | AllowMultipleAttributes | LongAttribute | ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove,
   1)
 DECL_ATTR(objc, ObjC,
   OnAbstractFunction | OnClass | OnProtocol | OnExtension | OnVar | OnSubscript | OnEnum | OnEnumElement | ABIBreakingToAdd | ABIBreakingToRemove | APIStableToAdd | APIStableToRemove,

include/swift/AST/DiagnosticsSema.def

@@ -2851,7 +2851,6 @@ WARNING(assoc_type_default_conformance_failed,none,
 NOTE(assoc_type_default_here,none,
      "associated type %0 has default type %1 written here",
      (const AssociatedTypeDecl *, Type))
-
 ERROR(protocol_access,none,
       "%select{protocol must be declared %select{"
       "%select{private|fileprivate|internal|package|%error|%error}1"
@@ -6841,6 +6840,10 @@ ERROR(inlinable_decl_not_public,
 ERROR(inlinable_resilient_deinit,
       none, "deinitializer can only be '@inlinable' if the class is '@_fixed_layout'", ())
 
+ERROR(resilient_associated_type_less_available_requires_default,none,
+      "associated type %0 that is less available than its protocol must have a "
+      "default", (const AssociatedTypeDecl *))
+
 //------------------------------------------------------------------------------
 // MARK: @_specialize diagnostics
 //------------------------------------------------------------------------------

lib/Sema/TypeCheckAvailability.cpp

@@ -3880,10 +3880,16 @@ class TypeReprAvailabilityWalker : public ASTWalker {
   DeclAvailabilityFlags flags;
 
   bool checkIdentTypeRepr(IdentTypeRepr *ITR) {
+    ArrayRef<AssociatedTypeDecl *> primaryAssociatedTypes;
+
     if (auto *typeDecl = ITR->getBoundDecl()) {
       auto range = ITR->getNameLoc().getSourceRange();
       if (diagnoseDeclAvailability(typeDecl, range, nullptr, where, flags))
         return true;
+
+      if (auto protocol = dyn_cast<ProtocolDecl>(typeDecl)) {
+        primaryAssociatedTypes = protocol->getPrimaryAssociatedTypes();
+      }
     }
 
     bool foundAnyIssues = false;
@@ -3895,6 +3901,17 @@ class TypeReprAvailabilityWalker : public ASTWalker {
       for (auto *genericArg : GTR->getGenericArgs()) {
         if (diagnoseTypeReprAvailability(genericArg, where, genericFlags))
           foundAnyIssues = true;
+
+        // The associated type that is being specified must be available as
+        // well.
+        if (!primaryAssociatedTypes.empty()) {
+          auto primaryAssociatedType = primaryAssociatedTypes.front();
+          primaryAssociatedTypes = primaryAssociatedTypes.drop_front();
+          if (diagnoseDeclAvailability(
+                  primaryAssociatedType, genericArg->getSourceRange(),
+                  nullptr, where, genericFlags))
+            foundAnyIssues = true;
+        }
       }
     }
 

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -2866,6 +2866,16 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
         AT->diagnose(diag::kind_declared_here, DescriptiveDeclKind::Type);
       }
     }
+
+    // An associated type that was introduced after the protocol
+    auto module = AT->getDeclContext()->getParentModule();
+    if (!defaultType &&
+        module->getResilienceStrategy() == ResilienceStrategy::Resilient &&
+        AvailabilityInference::availableRange(proto, Ctx)
+          .isSupersetOf(AvailabilityInference::availableRange(AT, Ctx))) {
+      AT->diagnose(
+          diag::resilient_associated_type_less_available_requires_default, AT);
+    }
   }
 
   void checkUnsupportedNestedType(NominalTypeDecl *NTD) {

test/IRGen/weak_import_associated_conformance_descriptor.swift

@@ -19,6 +19,13 @@ public protocol StrongProtoWithWeakLinkedAssoc {
   @_weakLinked associatedtype Assoc: P
 }
 
+public struct LibConformsToP: P { }
+
+public protocol StrongProtoWithNewAssoc {
+  @available(macOS 10.50, *)
+  associatedtype NewerAssoc: P = LibConformsToP
+}
+
 @available(macOS 10.50, *)
 public protocol WeakProtoWithAssoc {
   associatedtype Assoc: P
@@ -40,11 +47,18 @@ struct ConformsToStrongProtoWithAssoc: StrongProtoWithAssoc {
   typealias Assoc = ConformsToP
 }
 
+
 // CHECK: @"$s7Library30StrongProtoWithWeakLinkedAssocP0G0AC_AA1PTn" = extern_weak global %swift.protocol_requirement, align 4
 struct ConformsToStrongProtoWithWeakLinkedAssoc: StrongProtoWithWeakLinkedAssoc {
   typealias Assoc = ConformsToP
 }
 
+// CHECK: @"$s7Library23StrongProtoWithNewAssocP05NewerF0AC_AA1PTn" = extern_weak global %swift.protocol_requirement, align 4
+// CHECK: @"$s10NewerAssoc7Library018StrongProtoWithNewB0PTl" = extern_weak global %swift.protocol_requirement, align 4
+struct ConformsToStrongProtoWithNewAssoc: StrongProtoWithNewAssoc {
+  typealias NewAssoc = ConformsToP
+}
+
 // CHECK: @"$s7Library18WeakProtoWithAssocP0E0AC_AA1PTn" = extern_weak global %swift.protocol_requirement, align 4
 @available(macOS 10.50, *)
 struct ConformsToWeakProtoWithAssoc: WeakProtoWithAssoc {

test/Parse/invalid.swift

@@ -148,5 +148,5 @@ class C_50734<@NSApplicationMain T: AnyObject> {} // expected-error {{@NSApplica
 func f6_50734<@discardableResult T>(x: T) {} // expected-error {{'@discardableResult' attribute cannot be applied to this declaration}}
 enum E_50734<@indirect T> {} // expected-error {{'indirect' is a declaration modifier, not an attribute}} expected-error {{'indirect' modifier cannot be applied to this declaration}}
 protocol P {
-  @available(swift, introduced: 4.2) associatedtype Assoc // expected-error {{'@available' attribute cannot be applied to this declaration}}
+  @available(swift, introduced: 4) associatedtype Assoc
 }

test/api-digester/Outputs/Cake-abi.txt

@@ -61,6 +61,8 @@ cake: Accessor GlobalLetChangedToVar.Modify() is a new API without @available at
 cake: Accessor GlobalLetChangedToVar.Set() is a new API without @available attribute
 cake: Accessor fixedLayoutStruct2.BecomeFixedBinaryOrder.Modify() is a new API without @available attribute
 cake: Accessor fixedLayoutStruct2.BecomeFixedBinaryOrder.Set() is a new API without @available attribute
+cake: AssociatedType RequirementChanges.addedTypeWithDefault is a new API without @available attribute
+cake: AssociatedType RequirementChanges.addedTypeWithoutDefault is a new API without @available attribute
 cake: Class C0 is a new API without @available attribute
 cake: Class C8 is a new API without @available attribute
 cake: Constructor AddingNewDesignatedInit.init(_:) is a new API without @available attribute

test/attr/attr_inlinable_available.swift

@@ -1467,8 +1467,11 @@ public protocol NoAvailableProtoWithAssoc { // expected-note 3 {{add @available
   associatedtype B: BeforeInliningTargetProto
   associatedtype C: AtInliningTargetProto
   associatedtype D: BetweenTargetsProto // expected-error {{'BetweenTargetsProto' is only available in macOS 10.14.5 or newer; clients of 'Test' may have a lower deployment target}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
   associatedtype E: AtDeploymentTargetProto // expected-error {{'AtDeploymentTargetProto' is only available in macOS 10.15 or newer; clients of 'Test' may have a lower deployment target}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
   associatedtype F: AfterDeploymentTargetProto // expected-error {{'AfterDeploymentTargetProto' is only available in}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
 }
 
 @available(macOS 10.9, *)
@@ -1477,8 +1480,11 @@ public protocol BeforeInliningTargetProtoWithAssoc {
   associatedtype B: BeforeInliningTargetProto
   associatedtype C: AtInliningTargetProto
   associatedtype D: BetweenTargetsProto // expected-error {{'BetweenTargetsProto' is only available in macOS 10.14.5 or newer; clients of 'Test' may have a lower deployment target}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
   associatedtype E: AtDeploymentTargetProto // expected-error {{'AtDeploymentTargetProto' is only available in macOS 10.15 or newer; clients of 'Test' may have a lower deployment target}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
   associatedtype F: AfterDeploymentTargetProto // expected-error {{'AfterDeploymentTargetProto' is only available in}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
 }
 
 @available(macOS 10.10, *)
@@ -1487,8 +1493,11 @@ public protocol AtInliningTargetProtoWithAssoc {
   associatedtype B: BeforeInliningTargetProto
   associatedtype C: AtInliningTargetProto
   associatedtype D: BetweenTargetsProto // expected-error {{'BetweenTargetsProto' is only available in macOS 10.14.5 or newer; clients of 'Test' may have a lower deployment target}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
   associatedtype E: AtDeploymentTargetProto // expected-error {{'AtDeploymentTargetProto' is only available in macOS 10.15 or newer; clients of 'Test' may have a lower deployment target}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
   associatedtype F: AfterDeploymentTargetProto // expected-error {{'AfterDeploymentTargetProto' is only available in}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
 }
 
 @available(macOS 10.14.5, *)
@@ -1498,7 +1507,9 @@ public protocol BetweenTargetsProtoWithAssoc {
   associatedtype C: AtInliningTargetProto
   associatedtype D: BetweenTargetsProto
   associatedtype E: AtDeploymentTargetProto // expected-error {{'AtDeploymentTargetProto' is only available in macOS 10.15 or newer; clients of 'Test' may have a lower deployment target}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
   associatedtype F: AfterDeploymentTargetProto // expected-error {{'AfterDeploymentTargetProto' is only available in}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
 }
 
 @available(macOS 10.15, *)
@@ -1509,6 +1520,7 @@ public protocol AtDeploymentTargetProtoWithAssoc {
   associatedtype D: BetweenTargetsProto
   associatedtype E: AtDeploymentTargetProto
   associatedtype F: AfterDeploymentTargetProto // expected-error {{'AfterDeploymentTargetProto' is only available in}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
 }
 
 @available(macOS 11, *)
@@ -1529,6 +1541,7 @@ public protocol UnavailableProtoWithAssoc {
   associatedtype D: BetweenTargetsProto
   associatedtype E: AtDeploymentTargetProto
   associatedtype F: AfterDeploymentTargetProto // expected-error {{'AfterDeploymentTargetProto' is only available in}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
   associatedtype G: UnavailableProto
 }
 
@@ -1540,6 +1553,7 @@ public protocol SPINoAvailableProtoWithAssoc { // expected-note 1 {{add @availab
   associatedtype D: BetweenTargetsProto
   associatedtype E: AtDeploymentTargetProto
   associatedtype F: AfterDeploymentTargetProto // expected-error {{'AfterDeploymentTargetProto' is only available in}}
+  // expected-note@-1{{add @available attribute to enclosing associated type}}
 }
 
 // MARK: - Type aliases

test/decl/protocol/associated_type_availability.swift

@@ -0,0 +1,55 @@
+// RUN: %swift -typecheck -verify -target %target-cpu-apple-macosx12 %s
+// REQUIRES: OS=macosx
+
+
+protocol P { }
+extension Int: P { }
+
+protocol P1<A, B> {
+  associatedtype A
+
+  @available(macOS 13, *)
+  associatedtype B: P
+}
+
+@available(macOS 13, *)
+struct ModelP1<A, B: P>: P1 {
+}
+
+// Associated types in where clauses
+func testWhereBad<T: P1, U>(_: T) where T.B == U { }
+// expected-error@-1{{'B' is only available in macOS 13 or newer}}
+// expected-note@-2{{add @available attribute to enclosing global function}}
+
+@available(macOS 13, *)
+func testWhereGood<T: P1, U>(_: T) where T.B == U { }
+
+// Associated types in opaque parameter position
+func testPrimaryOpaqueParamBad<U>(_: some P1<some Any, U>) {}
+// expected-error@-1 2{{'B' is only available in macOS 13 or newer}}
+// expected-note@-2 2{{add @available attribute to enclosing global function}}
+
+@available(macOS 13, *)
+func testPrimaryOpaqueParamGood<U: P>(_: some P1<some Any, U>) {}
+
+// Associated types in opaque result position
+func testPrimaryOpaqueResultBad<U: P>() -> some P1<String, U> {
+// expected-error@-1{{'B' is only available in macOS 13 or newer}}
+// expected-note@-2 2{{add @available attribute to enclosing global function}}
+  return ModelP1<String, U>()
+  // expected-error@-1{{'ModelP1' is only available in macOS 13 or newer}}
+  // expected-note@-2{{add 'if #available' version check}}
+}
+
+@available(macOS 13, *)
+func testPrimaryOpaqueResultGood<U: P>() -> some P1<String, U> {
+  return ModelP1<String, U>()
+}
+
+// Associated types in existentials
+func testPrimaryExistentialBad<U>(_: any P1<Int, U>) {}
+// expected-error@-1{{'B' is only available in macOS 13 or newer}}
+// expected-note@-2{{add @available attribute to enclosing global function}}
+
+@available(macOS 13, *)
+func testPrimaryExistentialGood<U>(_: any P1<Int, U>) {}

test/decl/protocol/associated_type_availability_resilient.swift

@@ -0,0 +1,18 @@
+// RUN: %swift -typecheck -verify -target %target-cpu-apple-macosx12 %s -enable-library-evolution
+// REQUIRES: OS=macosx
+
+
+protocol P { }
+extension Int: P { }
+
+@available(macOS 12, *)
+protocol P1 {
+  associatedtype A
+
+  @available(macOS 13, *)
+  associatedtype B: P
+  // expected-error@-1{{associated type 'B' that is less available than its protocol must have a default}}
+
+  @available(macOS 13, *)
+  associatedtype C: P = Int
+}