Revert "Revert "Remove @actorIndependent attribute.""

This reverts commit 7c0b50e.

Author: DougGregor

include/swift/AST/Attr.def

@@ -574,12 +574,7 @@ CONTEXTUAL_SIMPLE_DECL_ATTR(actor, Actor,
   APIBreakingToAdd | APIBreakingToRemove,
   102)
 
-DECL_ATTR(actorIndependent, ActorIndependent,
-  OnClass | OnStruct | OnEnum | OnExtension | OnFunc | OnConstructor |
-  OnVar | OnSubscript | ConcurrencyOnly |
-  ABIBreakingToAdd | ABIBreakingToRemove |
-  APIBreakingToAdd | APIBreakingToRemove,
-  103)
+// Unused attribute 103
 
 SIMPLE_DECL_ATTR(globalActor, GlobalActor,
   OnClass | OnStruct | OnEnum | ConcurrencyOnly |

include/swift/AST/Attr.h

@@ -162,10 +162,6 @@ class DeclAttribute : public AttributeBase {
       kind : NumInlineKindBits
     );
 
-    SWIFT_INLINE_BITFIELD(ActorIndependentAttr, DeclAttribute, NumActorIndependentKindBits,
-      kind : NumActorIndependentKindBits
-    );
-
     SWIFT_INLINE_BITFIELD(OptimizeAttr, DeclAttribute, NumOptimizationModeBits,
       mode : NumOptimizationModeBits
     );
@@ -1223,25 +1219,6 @@ class ReferenceOwnershipAttr : public DeclAttribute {
   }
 };
 
-/// Represents an actorIndependent/actorIndependent(unsafe) decl attribute.
-class ActorIndependentAttr : public DeclAttribute {
-public:
-  ActorIndependentAttr(SourceLoc atLoc, SourceRange range, ActorIndependentKind kind)
-      : DeclAttribute(DAK_ActorIndependent, atLoc, range, /*Implicit=*/false) {
-    Bits.ActorIndependentAttr.kind = unsigned(kind);
-  }
-
-  ActorIndependentAttr(ActorIndependentKind kind, bool IsImplicit=false)
-    : ActorIndependentAttr(SourceLoc(), SourceRange(), kind) {
-      setImplicit(IsImplicit);
-    }
-
-  ActorIndependentKind getKind() const { return ActorIndependentKind(Bits.ActorIndependentAttr.kind); }
-  static bool classof(const DeclAttribute *DA) {
-    return DA->getKind() == DAK_ActorIndependent;
-  }
-};
-
 /// Defines the attribute that we use to model documentation comments.
 class RawDocCommentAttr : public DeclAttribute {
   /// Source range of the attached comment.  This comment is located before

include/swift/AST/AttrKind.h

@@ -80,16 +80,6 @@ enum : unsigned { NumInlineKindBits =
   countBitsUsed(static_cast<unsigned>(InlineKind::Last_InlineKind)) };
 
 
-/// Indicates whether an actorIndependent decl is unsafe or not
-enum class ActorIndependentKind : uint8_t {
-  Safe = 0,
-  Unsafe = 1,
-  Last_InlineKind = Unsafe
-};
-
-enum : unsigned { NumActorIndependentKindBits =
-  countBitsUsed(static_cast<unsigned>(ActorIndependentKind::Last_InlineKind)) };
-
 /// This enum represents the possible values of the @_effects attribute.
 /// These values are ordered from the strongest guarantee to the weakest,
 /// so please do not reorder existing values.

include/swift/AST/DiagnosticsSema.def

@@ -4520,23 +4520,12 @@ ERROR(concurrent_value_inherit,none,
       "%select{| other than 'NSObject'}0",
       (bool, DeclName))
 
-ERROR(actorindependent_let,none,
-      "'@actorIndependent' is meaningless on 'let' declarations because "
-      "they are immutable",
-      ())
-ERROR(actorindependent_mutable_storage,none,
-      "'@actorIndependent' can not be applied to stored properties",
-      ())
-ERROR(actorindependent_local_var,none,
-      "'@actorIndependent' can not be applied to local variables",
-      ())
-
 ERROR(nonisolated_let,none,
       "'nonisolated' is meaningless on 'let' declarations because "
       "they are immutable",
       ())
 ERROR(nonisolated_mutable_storage,none,
-      "nonisolated' can not be applied to stored properties",
+      "'nonisolated' can not be applied to stored properties",
       ())
 ERROR(nonisolated_local_var,none,
       "'nonisolated' can not be applied to local variables",

lib/AST/Attr.cpp

@@ -790,7 +790,6 @@ bool DeclAttribute::printImpl(ASTPrinter &Printer, const PrintOptions &Options,
   case DAK_ReferenceOwnership:
   case DAK_Effects:
   case DAK_Optimize:
-  case DAK_ActorIndependent:
     if (DeclAttribute::isDeclModifier(getKind())) {
       Printer.printKeyword(getAttrName(), Options);
     } else if (Options.IsForSwiftInterface && getKind() == DAK_ResultBuilder) {
@@ -1178,15 +1177,6 @@ StringRef DeclAttribute::getAttrName() const {
     }
     llvm_unreachable("Invalid inline kind");
   }
-  case DAK_ActorIndependent: {
-    switch (cast<ActorIndependentAttr>(this)->getKind()) {
-    case ActorIndependentKind::Safe:
-      return "actorIndependent";
-    case ActorIndependentKind::Unsafe:
-      return "actorIndependent(unsafe)";
-    }
-    llvm_unreachable("Invalid actorIndependent kind");
-  }
   case DAK_Optimize: {
     switch (cast<OptimizeAttr>(this)->getMode()) {
     case OptimizationMode::NoOptimization:

lib/ClangImporter/ImportDecl.cpp

@@ -8706,6 +8706,14 @@ void ClangImporter::Implementation::importAttributes(
         continue;
       }
 
+      // Hard-code @actorIndependent, until Objective-C clients start
+      // using nonisolated.
+      if (swiftAttr->getAttribute() == "@actorIndependent") {
+        auto attr = new (SwiftContext) NonisolatedAttr(/*isImplicit=*/true);
+        MappedDecl->getAttrs().add(attr);
+        continue;
+      }
+
       // Dig out a buffer with the attribute text.
       unsigned bufferID = getClangSwiftAttrSourceBuffer(
           swiftAttr->getAttribute());
@@ -9630,9 +9638,8 @@ ClangImporter::Implementation::createConstant(Identifier name, DeclContext *dc,
 
   // Mark the function transparent so that we inline it away completely.
   func->getAttrs().add(new (C) TransparentAttr(/*implicit*/ true));
-  auto actorIndependentAttr = new (C) ActorIndependentAttr(
-      ActorIndependentKind::Unsafe, /*IsImplicit=*/true);
-  var->getAttrs().add(actorIndependentAttr);
+  auto nonisolatedAttr = new (C) NonisolatedAttr(/*IsImplicit=*/true);
+  var->getAttrs().add(nonisolatedAttr);
 
   // Set the function up as the getter.
   makeComputed(var, func, nullptr);

lib/Parse/ParseDecl.cpp

@@ -1784,45 +1784,6 @@ bool Parser::parseNewDeclAttribute(DeclAttributes &Attributes, SourceLoc AtLoc,
     break;
   }
 
-  case DAK_ActorIndependent: {
-    // if no option is provided, then it's the 'safe' version.
-    if (!consumeIf(tok::l_paren)) {
-      if (!DiscardAttribute) {
-        AttrRange = SourceRange(Loc, Tok.getRange().getStart());
-        Attributes.add(new (Context) ActorIndependentAttr(AtLoc, AttrRange, 
-                                                  ActorIndependentKind::Safe));
-      }
-      break;
-    }
-
-    // otherwise, make sure it looks like an identifier.
-    if (Tok.isNot(tok::identifier)) {
-      diagnose(Loc, diag::attr_expected_option_such_as, AttrName, "unsafe");
-      return false;
-    }
-
-    // make sure the identifier is 'unsafe'
-    if (Tok.getText() != "unsafe") {
-      diagnose(Loc, diag::attr_unknown_option, Tok.getText(), AttrName);
-      return false;
-    }
-
-    consumeToken(tok::identifier);
-    AttrRange = SourceRange(Loc, Tok.getRange().getStart());
-    
-    if (!consumeIf(tok::r_paren)) {
-      diagnose(Loc, diag::attr_expected_rparen, AttrName,
-               DeclAttribute::isDeclModifier(DK));
-      return false;
-    }
-
-    if (!DiscardAttribute)
-      Attributes.add(new (Context) ActorIndependentAttr(AtLoc, AttrRange, 
-                                                ActorIndependentKind::Unsafe));
-
-    break;
-  }
-
   case DAK_Optimize: {
     if (!consumeIf(tok::l_paren)) {
       diagnose(Loc, diag::attr_expected_lparen, AttrName,

lib/Sema/TypeCheckAttr.cpp

@@ -252,7 +252,6 @@ class AttributeChecker : public AttributeVisitor<AttributeChecker> {
 
   void visitActorAttr(ActorAttr *attr);
   void visitDistributedActorAttr(DistributedActorAttr *attr);
-  void visitActorIndependentAttr(ActorIndependentAttr *attr);
   void visitDistributedActorIndependentAttr(DistributedActorIndependentAttr *attr);
   void visitGlobalActorAttr(GlobalActorAttr *attr);
   void visitAsyncAttr(AsyncAttr *attr);
@@ -5391,7 +5390,6 @@ void AttributeChecker::visitActorAttr(ActorAttr *attr) {
   (void)classDecl->isActor();
 }
 
-
 void AttributeChecker::visitDistributedActorAttr(DistributedActorAttr *attr) {
   auto dc = D->getDeclContext();
 
@@ -5441,48 +5439,6 @@ void AttributeChecker::visitDistributedActorAttr(DistributedActorAttr *attr) {
   }
 }
 
-void AttributeChecker::visitActorIndependentAttr(ActorIndependentAttr *attr) {
-  // @actorIndependent can be applied to global and static/class variables
-  // that do not have storage.
-  auto dc = D->getDeclContext();
-  if (auto var = dyn_cast<VarDecl>(D)) {
-    // @actorIndependent is meaningless on a `let`.
-    if (var->isLet()) {
-      diagnoseAndRemoveAttr(attr, diag::actorindependent_let);
-      return;
-    }
-
-    // @actorIndependent can not be applied to stored properties, unless if
-    // the 'unsafe' option was specified
-    if (var->hasStorage()) {
-      switch (attr->getKind()) {
-        case ActorIndependentKind::Safe:
-          diagnoseAndRemoveAttr(attr, diag::actorindependent_mutable_storage);
-          return;
-
-        case ActorIndependentKind::Unsafe:
-          break;
-      }
-    }
-
-    // @actorIndependent can not be applied to local properties.
-    if (dc->isLocalContext()) {
-      diagnoseAndRemoveAttr(attr, diag::actorindependent_local_var);
-      return;
-    }
-
-    // If this is a static or global variable, we're all set.
-    if (dc->isModuleScopeContext() ||
-        (dc->isTypeContext() && var->isStatic())) {
-      return;
-    }
-  }
-
-  if (auto VD = dyn_cast<ValueDecl>(D)) {
-    (void)getActorIsolation(VD);
-  }
-}
-
 void AttributeChecker::visitNonisolatedAttr(NonisolatedAttr *attr) {
   // 'nonisolated' can be applied to global and static/class variables
   // that do not have storage.
@@ -5500,7 +5456,7 @@ void AttributeChecker::visitNonisolatedAttr(NonisolatedAttr *attr) {
       return;
     }
 
-    // @actorIndependent can not be applied to local properties.
+    // nonisolated can not be applied to local properties.
     if (dc->isLocalContext()) {
       diagnoseAndRemoveAttr(attr, diag::nonisolated_local_var);
       return;
@@ -5663,10 +5619,6 @@ class ClosureAttributeChecker
     // Nothing else to check.
   }
 
-  void visitActorIndependentAttr(ActorIndependentAttr *attr) {
-    // Nothing else to check.
-  }
-
   void visitCustomAttr(CustomAttr *attr) {
     // Check whether this custom attribute is the global actor attribute.
     auto globalActorAttr = evaluateOrDefault(

lib/Sema/TypeCheckConcurrency.cpp

@@ -2278,9 +2278,6 @@ namespace {
         AbstractClosureExpr *closure) {
       // If the closure specifies a global actor, use it.
       if (auto explicitClosure = dyn_cast<ClosureExpr>(closure)) {
-        if (explicitClosure->getAttrs().hasAttribute<ActorIndependentAttr>())
-          return ClosureActorIsolation::forIndependent();
-
         if (Type globalActorType = resolveGlobalActorType(explicitClosure))
           return ClosureActorIsolation::forGlobalActor(globalActorType);
 
@@ -2504,23 +2501,19 @@ static Optional<ActorIsolation> getIsolationFromAttributes(
     const Decl *decl, bool shouldDiagnose = true, bool onlyExplicit = false) {
   // Look up attributes on the declaration that can affect its actor isolation.
   // If any of them are present, use that attribute.
-  auto independentAttr = decl->getAttrs().getAttribute<ActorIndependentAttr>();
   auto nonisolatedAttr = decl->getAttrs().getAttribute<NonisolatedAttr>();
   auto globalActorAttr = decl->getGlobalActorAttr();
 
   // Remove implicit attributes if we only care about explicit ones.
   if (onlyExplicit) {
-    if (independentAttr && independentAttr->isImplicit())
-      independentAttr = nullptr;
     if (nonisolatedAttr && nonisolatedAttr->isImplicit())
       nonisolatedAttr = nullptr;
     if (globalActorAttr && globalActorAttr->first->isImplicit())
       globalActorAttr = None;
   }
 
   unsigned numIsolationAttrs =
-    (nonisolatedAttr ? 1 : 0) + (independentAttr ? 1 : 0) +
-    (globalActorAttr ? 1 : 0);
+    (nonisolatedAttr ? 1 : 0) + (globalActorAttr ? 1 : 0);
   if (numIsolationAttrs == 0)
     return None;
 
@@ -2536,22 +2529,12 @@ static Optional<ActorIsolation> getIsolationFromAttributes(
     }
 
     if (globalActorAttr) {
-      StringRef nonisolatedAttrName;
-      SourceRange nonisolatedRange;
-      if (independentAttr) {
-        nonisolatedAttrName = independentAttr->getAttrName();
-        nonisolatedRange = independentAttr->getRangeWithAt();
-      } else {
-        nonisolatedAttrName = nonisolatedAttr->getAttrName();
-        nonisolatedRange = nonisolatedAttr->getRangeWithAt();
-      }
-
       if (shouldDiagnose) {
         decl->diagnose(
             diag::actor_isolation_multiple_attr, decl->getDescriptiveKind(),
-            name, nonisolatedAttrName,
+            name, nonisolatedAttr->getAttrName(),
             globalActorAttr->second->getName().str())
-          .highlight(nonisolatedRange)
+          .highlight(nonisolatedAttr->getRangeWithAt())
           .highlight(globalActorAttr->first->getRangeWithAt());
       }
     }
@@ -2563,12 +2546,6 @@ static Optional<ActorIsolation> getIsolationFromAttributes(
     return ActorIsolation::forIndependent();
   }
 
-  // If the declaration is explicitly marked @actorIndependent, report it as
-  // independent.
-  if (independentAttr) {
-    return ActorIsolation::forIndependent();
-  }
-
   // If the declaration is marked with a global actor, report it as being
   // part of that global actor.
   if (globalActorAttr) {
@@ -2660,7 +2637,7 @@ static Optional<ActorIsolation> getIsolationFromWitnessedRequirements(
         llvm_unreachable("protocol requirements cannot be actor instances");
 
       case ActorIsolation::Independent:
-        // We only need one @actorIndependent.
+        // We only need one nonisolated.
         if (sawActorIndependent)
           return true;
 
@@ -2880,13 +2857,7 @@ ActorIsolation ActorIsolationRequest::evaluate(
       if (onlyGlobal)
         return ActorIsolation::forUnspecified();
 
-      if (auto varDecl = dyn_cast<VarDecl>(value)) {
-        // only set the @actorIndependent on values where it is legal to do so
-        if (!varDecl->isLet()) {
-          value->getAttrs().add(new (ctx) ActorIndependentAttr(
-              ActorIndependentKind::Safe, /*IsImplicit=*/true));
-        }
-      }
+      value->getAttrs().add(new (ctx) NonisolatedAttr(/*IsImplicit=*/true));
       break;
 
     case ActorIsolation::GlobalActorUnsafe:
@@ -3144,12 +3115,9 @@ void swift::checkOverrideActorIsolation(ValueDecl *value) {
 bool swift::contextUsesConcurrencyFeatures(const DeclContext *dc) {
   while (!dc->isModuleScopeContext()) {
     if (auto closure = dyn_cast<AbstractClosureExpr>(dc)) {
-      // A closure with an explicit global actor or @actorIndependent
+      // A closure with an explicit global actor or nonindependent
       // uses concurrency features.
       if (auto explicitClosure = dyn_cast<ClosureExpr>(closure)) {
-        if (explicitClosure->getAttrs().hasAttribute<ActorIndependentAttr>())
-          return true;
-
         if (getExplicitGlobalActor(const_cast<ClosureExpr *>(explicitClosure)))
           return true;
       }

lib/Sema/TypeCheckDeclOverride.cpp

@@ -1534,7 +1534,6 @@ namespace  {
     UNINTERESTING_ATTR(OriginallyDefinedIn)
     UNINTERESTING_ATTR(Actor)
     UNINTERESTING_ATTR(DistributedActor)
-    UNINTERESTING_ATTR(ActorIndependent)
     UNINTERESTING_ATTR(DistributedActorIndependent)
     UNINTERESTING_ATTR(GlobalActor)
     UNINTERESTING_ATTR(Async)