AST/Sema: Retire SemanticAvailableAttr::getVersionAvailability().

Query for availability constraints instead of calling getVersionAvailability().

Author: tshortli

include/swift/AST/Attr.h

@@ -703,23 +703,6 @@ class SwiftNativeObjCRuntimeBaseAttr : public DeclAttribute {
   }
 };
 
-/// Determine the result of comparing an availability attribute to a specific
-/// platform or language version.
-enum class AvailableVersionComparison {
-  /// The entity is guaranteed to be available.
-  Available,
-
-  /// The entity is never available.
-  Unavailable,
-
-  /// The entity might be unavailable at runtime, because it was introduced
-  /// after the requested minimum platform version.
-  PotentiallyUnavailable,
-
-  /// The entity has been obsoleted.
-  Obsoleted,
-};
-
 /// Defines the @available attribute.
 class AvailableAttr : public DeclAttribute {
 public:
@@ -3378,12 +3361,6 @@ class SemanticAvailableAttr final {
   /// version for PackageDescription version-specific availability.
   llvm::VersionTuple getActiveVersion(const ASTContext &ctx) const;
 
-  /// Compare this attribute's version information against the platform or
-  /// language version (assuming the this attribute pertains to the active
-  /// platform).
-  AvailableVersionComparison
-  getVersionAvailability(const ASTContext &ctx) const;
-
   /// Returns true if this attribute is considered active in the current
   /// compilation context.
   bool isActive(ASTContext &ctx) const;

lib/AST/Attr.cpp

@@ -2294,50 +2294,6 @@ SemanticAvailableAttr::getActiveVersion(const ASTContext &ctx) const {
   }
 }
 
-AvailableVersionComparison
-SemanticAvailableAttr::getVersionAvailability(const ASTContext &ctx) const {
-
-  // Unconditional unavailability.
-  if (attr->isUnconditionallyUnavailable())
-    return AvailableVersionComparison::Unavailable;
-
-  llvm::VersionTuple queryVersion = getActiveVersion(ctx);
-  std::optional<llvm::VersionTuple> ObsoletedVersion = getObsoleted();
-
-  StringRef ObsoletedPlatform;
-  llvm::VersionTuple RemappedObsoletedVersion;
-  if (AvailabilityInference::updateObsoletedPlatformForFallback(
-          *this, ctx, ObsoletedPlatform, RemappedObsoletedVersion))
-    ObsoletedVersion = RemappedObsoletedVersion;
-
-  // If this entity was obsoleted before or at the query platform version,
-  // consider it obsolete.
-  if (ObsoletedVersion && *ObsoletedVersion <= queryVersion)
-    return AvailableVersionComparison::Obsoleted;
-
-  std::optional<llvm::VersionTuple> IntroducedVersion = getIntroduced();
-  StringRef IntroducedPlatform;
-  llvm::VersionTuple RemappedIntroducedVersion;
-  if (AvailabilityInference::updateIntroducedPlatformForFallback(
-          *this, ctx, IntroducedPlatform, RemappedIntroducedVersion))
-    IntroducedVersion = RemappedIntroducedVersion;
-
-  // If this entity was introduced after the query version and we're doing a
-  // platform comparison, true availability can only be determined dynamically;
-  // if we're doing a _language_ version check, the query version is a
-  // static requirement, so we treat "introduced later" as just plain
-  // unavailable.
-  if (IntroducedVersion && *IntroducedVersion > queryVersion) {
-    if (isSwiftLanguageModeSpecific() || isPackageDescriptionVersionSpecific())
-      return AvailableVersionComparison::Unavailable;
-    else
-      return AvailableVersionComparison::PotentiallyUnavailable;
-  }
-
-  // The entity is available.
-  return AvailableVersionComparison::Available;
-}
-
 SpecializeAttr::SpecializeAttr(SourceLoc atLoc, SourceRange range,
                                TrailingWhereClause *clause, bool exported,
                                SpecializationKind kind,

lib/Sema/TypeCheckAttr.cpp

@@ -2417,27 +2417,6 @@ void AttributeChecker::visitAvailableAttr(AvailableAttr *parsedAttr) {
     }
   }
 
-  SourceLoc attrLoc = parsedAttr->getLocation();
-  auto versionAvailability = attr->getVersionAvailability(Ctx);
-  if (versionAvailability == AvailableVersionComparison::Obsoleted ||
-      versionAvailability == AvailableVersionComparison::Unavailable) {
-    if (auto cannotBeUnavailable =
-            TypeChecker::diagnosticIfDeclCannotBeUnavailable(D)) {
-      diagnose(attrLoc, cannotBeUnavailable.value());
-      return;
-    }
-
-    if (auto *PD = dyn_cast<ProtocolDecl>(DC)) {
-      if (auto *VD = dyn_cast<ValueDecl>(D)) {
-        if (VD->isProtocolRequirement() && !PD->isObjC()) {
-          diagnoseAndRemoveAttr(parsedAttr,
-                                diag::unavailable_method_non_objc_protocol);
-          return;
-        }
-      }
-    }
-  }
-
   // The remaining diagnostics are only for attributes with introduced versions
   // for specific platforms.
   if (!attr->isPlatformSpecific() || !attr->getIntroduced().has_value())
@@ -2486,18 +2465,6 @@ void AttributeChecker::visitAvailableAttr(AvailableAttr *parsedAttr) {
       }
     }
   }
-
-  std::optional<Diagnostic> MaybeNotAllowed =
-      TypeChecker::diagnosticIfDeclCannotBePotentiallyUnavailable(D);
-  if (MaybeNotAllowed.has_value()) {
-    AvailabilityRange DeploymentRange =
-        AvailabilityRange::forDeploymentTarget(Ctx);
-    if (EnclosingAnnotatedRange.has_value())
-      DeploymentRange.intersectWith(*EnclosingAnnotatedRange);
-
-    if (!DeploymentRange.isContainedIn(AttrRange))
-      diagnose(attrLoc, MaybeNotAllowed.value());
-  }
 }
 
 static bool canDeclareSymbolName(StringRef symbol, ModuleDecl *fromModule) {
@@ -5003,6 +4970,54 @@ void AttributeChecker::checkAvailableAttrs(ArrayRef<AvailableAttr *> Attrs) {
       diagnose(D->getLoc(), diag::spi_preferred_over_spi_available);
     }
   }
+
+  if (Ctx.LangOpts.DisableAvailabilityChecking)
+    return;
+
+  // Compute availability constraints for the decl, relative to its parent
+  // declaration or to the deployment target.
+  auto availabilityContext = AvailabilityContext::forDeploymentTarget(Ctx);
+  if (auto parent =
+          AvailabilityInference::parentDeclForInferredAvailability(D)) {
+    auto parentAvailability = TypeChecker::availabilityForDeclSignature(parent);
+    availabilityContext.constrainWithContext(parentAvailability, Ctx);
+  }
+
+  auto availabilityConstraint =
+      getAvailabilityConstraintsForDecl(D, availabilityContext)
+          .getPrimaryConstraint();
+  if (!availabilityConstraint)
+    return;
+
+  // If the decl is unavailable relative to its parent and it's not a
+  // declaration that is allowed to be unavailable, diagnose.
+  if (availabilityConstraint->isUnavailable()) {
+    auto attr = availabilityConstraint->getAttr();
+    if (auto diag = TypeChecker::diagnosticIfDeclCannotBeUnavailable(D)) {
+      diagnose(attr.getParsedAttr()->getLocation(), diag.value());
+      return;
+    }
+
+    if (auto *PD = dyn_cast<ProtocolDecl>(D->getDeclContext())) {
+      if (auto *VD = dyn_cast<ValueDecl>(D)) {
+        if (VD->isProtocolRequirement() && !PD->isObjC()) {
+          diagnoseAndRemoveAttr(
+              const_cast<AvailableAttr *>(attr.getParsedAttr()),
+              diag::unavailable_method_non_objc_protocol);
+          return;
+        }
+      }
+    }
+  }
+
+  // If the decl is potentially unavailable relative to its parent and it's
+  // not a declaration that is allowed to be potentially unavailable, diagnose.
+  if (availabilityConstraint->isPotentiallyAvailable()) {
+    auto attr = availabilityConstraint->getAttr();
+    if (auto diag =
+            TypeChecker::diagnosticIfDeclCannotBePotentiallyUnavailable(D))
+      diagnose(attr.getParsedAttr()->getLocation(), diag.value());
+  }
 }
 
 void AttributeChecker::checkBackDeployedAttrs(

lib/Sema/TypeCheckDeclOverride.cpp

@@ -245,15 +245,21 @@ bool swift::isOverrideBasedOnType(const ValueDecl *decl, Type declTy,
 
 static bool isUnavailableInAllVersions(ValueDecl *decl) {
   ASTContext &ctx = decl->getASTContext();
-  auto attr = decl->getUnavailableAttr();
-  if (!attr)
-    return false;
 
-  if (attr->isUnconditionallyUnavailable())
-    return true;
+  auto deploymentContext = AvailabilityContext::forDeploymentTarget(ctx);
+  auto constraints = getAvailabilityConstraintsForDecl(decl, deploymentContext);
+  for (auto constraint : constraints) {
+    switch (constraint.getReason()) {
+    case AvailabilityConstraint::Reason::UnconditionallyUnavailable:
+    case AvailabilityConstraint::Reason::IntroducedInLaterVersion:
+      return true;
+    case AvailabilityConstraint::Reason::Obsoleted:
+    case AvailabilityConstraint::Reason::IntroducedInLaterDynamicVersion:
+      break;
+    }
+  }
 
-  return attr->getVersionAvailability(ctx) ==
-         AvailableVersionComparison::Unavailable;
+  return false;
 }
 
 /// Perform basic checking to determine whether a declaration can override a

test/Parse/invalid.swift

@@ -140,5 +140,5 @@ 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) associatedtype Assoc
+  @available(macOS, introduced: 10.9) associatedtype Assoc
 }

test/decl/protocol/associated_type_availability.swift

@@ -89,6 +89,6 @@ protocol P3 {
   @available(macOS, obsoleted: 12) // expected-error{{associated type cannot be marked unavailable with '@available'}}
   associatedtype A1
 
-  @available(macOS, obsoleted: 99) // FIXME: this should probably be diagnosed
+  @available(macOS, obsoleted: 99)
   associatedtype A2
 }

test/decl/protocol/req/unavailable.swift

@@ -104,6 +104,15 @@ protocol UnavailableAssoc {
   @available(*, unavailable) // expected-error {{associated type cannot be marked unavailable with '@available'}}
   associatedtype A1
 
-  @available(swift, introduced: 99) // expected-error {{associated type cannot be marked unavailable with '@available'}}
+  @available(swift, introduced: 4)
   associatedtype A2
+
+  @available(swift, introduced: 99) // expected-error {{associated type cannot be marked unavailable with '@available'}}
+  associatedtype A3
+
+  @available(swift, obsoleted: 4) // expected-error {{associated type cannot be marked unavailable with '@available'}}
+  associatedtype A4
+
+  @available(swift, obsoleted: 99)
+  associatedtype A5
 }