[Distributed] Enable no-longer-experimental distributed by default

CHANGELOG.md

@@ -5,6 +5,36 @@ _**Note:** This is in reverse chronological order, so newer entries are added to
 
 ## Swift 5.7
 
+* [SE-0336][]:
+
+It is now possible to declare `distributed actor` and `distributed func`s inside of them.
+
+Distributed actors provide stronger isolation guarantees than "local" actors, and enable additional checks to be made on return types and parameters of distributed methods, e.g. checking if they conform to `Codable`. Distributed methods can be called on "remote" references of distributed actors, turning those invocations into remote procedure calls, by means of pluggable and user extensible distributed actor system implementations. 
+
+Swift does not provide any specific distributed actor system by itself, however, packages in the ecosystem fulfil the role of providing those implementations.
+
+```swift
+distributed actor Greeter { 
+  var greetingsSent = 0
+
+  distributed func greet(name: String) -> String {
+    greetingsSent += 1
+    return "Hello, \(name)!"
+  }
+}
+
+func talkTo(greeter: Greeter) async throws {
+  // isolation of distributed actors is stronger, it is impossible to refer to
+  // any stored properties of distributed actors from outside of them:
+  greeter.greetingsSent // distributed actor-isolated property 'name' can not be accessed from a non-isolated context
+
+  // remote calls are implicitly throwing and async, 
+  // to account for the potential networking involved:
+  let greeting = try await greeter.greet(name: "Alice")
+  print(greeting) // Hello, Alice!
+}
+```
+
 * The compiler now emits a warning when a non-final class conforms to a protocol that imposes a same-type requirement between `Self` and an associated type. This is because such a requirement makes the conformance unsound for subclasses.
 
 For example, Swift 5.6 would allow the following code, which at runtime would construct an instanec of `C` and not `SubC` as expected:
@@ -9034,6 +9064,7 @@ Swift 1.0
 [SE-0337]: <https://github.com/apple/swift-evolution/blob/main/proposals/0337-support-incremental-migration-to-concurrency-checking.md>
 [SE-0335]: <https://github.com/apple/swift-evolution/blob/main/proposals/0335-existential-any.md>
 [SE-0341]: <https://github.com/apple/swift-evolution/blob/main/proposals/0341-opaque-parameters.md>
+[SE-0336]: <https://github.com/apple/swift-evolution/blob/main/proposals/0336-distributed-actor-isolation.md>
 
 [SR-75]: <https://bugs.swift.org/browse/SR-75>
 [SR-106]: <https://bugs.swift.org/browse/SR-106>

include/swift/AST/DiagnosticsParse.def

@@ -1887,11 +1887,6 @@ ERROR(attr_requires_concurrency, none,
       "concurrency is enabled",
       (StringRef, bool))
 
-ERROR(attr_requires_distributed, none,
-      "'%0' %select{attribute|modifier}1 is only valid when experimental "
-      "distributed support is enabled",
-      (StringRef, bool))
-
 //------------------------------------------------------------------------------
 // MARK: syntax parsing diagnostics
 //------------------------------------------------------------------------------

include/swift/Basic/LangOptions.h

@@ -344,7 +344,7 @@ namespace swift {
     bool EnableInferPublicSendable = false;
 
     /// Enable experimental 'distributed' actors and functions.
-    bool EnableExperimentalDistributed = false;
+    bool EnableExperimentalDistributed = true;
 
     /// Enable experimental 'move only' features.
     bool EnableExperimentalMoveOnly = false;

include/swift/IDE/CompletionLookup.h

@@ -541,7 +541,6 @@ class CompletionLookup final : public swift::VisibleDeclConsumer {
 
   static bool canUseAttributeOnDecl(DeclAttrKind DAK, bool IsInSil,
                                     bool IsConcurrencyEnabled,
-                                    bool IsDistributedEnabled,
                                     Optional<DeclKind> DK);
 
   void getAttributeDeclCompletions(bool IsInSil, Optional<DeclKind> DK);

include/swift/Parse/Parser.h

@@ -748,14 +748,6 @@ class Parser {
       Context.LangOpts.ParseForSyntaxTreeOnly;
   }
 
-  /// Returns true to indicate that experimental 'distributed actor' syntax
-  /// should be parsed if the parser is only a syntax tree or if the user has
-  /// passed the `-enable-experimental-distributed' flag to the frontend.
-  bool shouldParseExperimentalDistributed() const {
-    return Context.LangOpts.EnableExperimentalDistributed ||
-      Context.LangOpts.ParseForSyntaxTreeOnly;
-  }
-
 public:
   InFlightDiagnostic diagnose(SourceLoc Loc, Diagnostic Diag) {
     if (Diags.isDiagnosticPointsToFirstBadToken(Diag.getID()) &&

lib/AST/ASTContext.cpp

@@ -3028,23 +3028,21 @@ AnyFunctionType::Param swift::computeSelfParam(AbstractFunctionDecl *AFD,
       // FIXME(distributed): pending swift-evolution, allow `self =` in class
       //  inits in general.
       //  See also: https://github.com/apple/swift/pull/19151 general impl
-      if (Ctx.LangOpts.EnableExperimentalDistributed) {
-        auto ext = dyn_cast<ExtensionDecl>(AFD->getDeclContext());
-        auto distProto =
-            Ctx.getProtocol(KnownProtocolKind::DistributedActor);
-        if (distProto && ext && ext->getExtendedNominal() &&
-            ext->getExtendedNominal()->getInterfaceType()
-                ->isEqual(distProto->getInterfaceType())) {
-          auto name = CD->getName();
-          auto params = name.getArgumentNames();
-          if (params.size() == 1 && params[0] == Ctx.Id_from) {
-            // FIXME(distributed): this is a workaround to allow init(from:) to
-            //  be implemented in AST by allowing the self to be mutable in the
-            //  decoding initializer. This should become a general Swift
-            //  feature, allowing this in all classes:
-            //  https://forums.swift.org/t/allow-self-x-in-class-convenience-initializers/15924
-            selfAccess = SelfAccessKind::Mutating;
-          }
+      auto ext = dyn_cast<ExtensionDecl>(AFD->getDeclContext());
+      auto distProto =
+          Ctx.getProtocol(KnownProtocolKind::DistributedActor);
+      if (distProto && ext && ext->getExtendedNominal() &&
+          ext->getExtendedNominal()->getInterfaceType()
+              ->isEqual(distProto->getInterfaceType())) {
+        auto name = CD->getName();
+        auto params = name.getArgumentNames();
+        if (params.size() == 1 && params[0] == Ctx.Id_from) {
+          // FIXME(distributed): this is a workaround to allow init(from:) to
+          //  be implemented in AST by allowing the self to be mutable in the
+          //  decoding initializer. This should become a general Swift
+          //  feature, allowing this in all classes:
+          //  https://forums.swift.org/t/allow-self-x-in-class-convenience-initializers/15924
+          selfAccess = SelfAccessKind::Mutating;
         }
       }
     } else {

lib/IDE/CodeCompletion.cpp

@@ -656,8 +656,7 @@ static void addKeyword(CodeCompletionResultSink &Sink, StringRef Name,
 }
 
 static void addDeclKeywords(CodeCompletionResultSink &Sink, DeclContext *DC,
-                            bool IsConcurrencyEnabled,
-                            bool IsDistributedEnabled) {
+                            bool IsConcurrencyEnabled) {
   auto isTypeDeclIntroducer = [](CodeCompletionKeywordKind Kind,
                                  Optional<DeclAttrKind> DAK) -> bool {
     switch (Kind) {
@@ -778,11 +777,6 @@ static void addDeclKeywords(CodeCompletionResultSink &Sink, DeclContext *DC,
         DeclAttribute::isConcurrencyOnly(*DAK))
       return;
 
-    // Remove keywords only available when distributed is enabled.
-    if (DAK.hasValue() && !IsDistributedEnabled &&
-        DeclAttribute::isDistributedOnly(*DAK))
-      return;
-
     addKeyword(Sink, Name, Kind, /*TypeAnnotation=*/"", getFlair(Kind, DAK));
   };
 
@@ -943,8 +937,7 @@ void CodeCompletionCallbacksImpl::addKeywords(CodeCompletionResultSink &Sink,
   }
   case CompletionKind::StmtOrExpr:
     addDeclKeywords(Sink, CurDeclContext,
-                    Context.LangOpts.EnableExperimentalConcurrency,
-                    Context.LangOpts.EnableExperimentalDistributed);
+                    Context.LangOpts.EnableExperimentalConcurrency);
     addStmtKeywords(Sink, CurDeclContext, MaybeFuncBody);
     LLVM_FALLTHROUGH;
   case CompletionKind::ReturnStmtExpr:
@@ -1013,8 +1006,7 @@ void CodeCompletionCallbacksImpl::addKeywords(CodeCompletionResultSink &Sink,
     }) != ParsedKeywords.end();
     if (!HasDeclIntroducer) {
       addDeclKeywords(Sink, CurDeclContext,
-                      Context.LangOpts.EnableExperimentalConcurrency,
-                      Context.LangOpts.EnableExperimentalDistributed);
+                      Context.LangOpts.EnableExperimentalConcurrency);
       addLetVarKeywords(Sink);
     }
     break;
@@ -1758,8 +1750,7 @@ void CodeCompletionCallbacksImpl::doneParsing() {
         if (CurDeclContext->isTypeContext()) {
           // Override completion (CompletionKind::NominalMemberBeginning).
           addDeclKeywords(Sink, CurDeclContext,
-                          Context.LangOpts.EnableExperimentalConcurrency,
-                          Context.LangOpts.EnableExperimentalDistributed);
+                          Context.LangOpts.EnableExperimentalConcurrency);
           addLetVarKeywords(Sink);
           SmallVector<StringRef, 0> ParsedKeywords;
           CompletionOverrideLookup OverrideLookup(Sink, Context, CurDeclContext,
@@ -1768,8 +1759,7 @@ void CodeCompletionCallbacksImpl::doneParsing() {
         } else {
           // Global completion (CompletionKind::PostfixExprBeginning).
           addDeclKeywords(Sink, CurDeclContext,
-                          Context.LangOpts.EnableExperimentalConcurrency,
-                          Context.LangOpts.EnableExperimentalDistributed);
+                          Context.LangOpts.EnableExperimentalConcurrency);
           addStmtKeywords(Sink, CurDeclContext, MaybeFuncBody);
           addSuperKeyword(Sink, CurDeclContext);
           addLetVarKeywords(Sink);

lib/IDE/CompletionLookup.cpp

@@ -2852,7 +2852,6 @@ void CompletionLookup::getGenericRequirementCompletions(
 
 bool CompletionLookup::canUseAttributeOnDecl(DeclAttrKind DAK, bool IsInSil,
                                              bool IsConcurrencyEnabled,
-                                             bool IsDistributedEnabled,
                                              Optional<DeclKind> DK) {
   if (DeclAttribute::isUserInaccessible(DAK))
     return false;
@@ -2864,8 +2863,6 @@ bool CompletionLookup::canUseAttributeOnDecl(DeclAttrKind DAK, bool IsInSil,
     return false;
   if (!IsConcurrencyEnabled && DeclAttribute::isConcurrencyOnly(DAK))
     return false;
-  if (!IsDistributedEnabled && DeclAttribute::isDistributedOnly(DAK))
-    return false;
   if (!DK.hasValue())
     return true;
   return DeclAttribute::canAttributeAppearOnDeclKind(DAK, DK.getValue());
@@ -2885,11 +2882,10 @@ void CompletionLookup::getAttributeDeclCompletions(bool IsInSil,
     }
   }
   bool IsConcurrencyEnabled = Ctx.LangOpts.EnableExperimentalConcurrency;
-  bool IsDistributedEnabled = Ctx.LangOpts.EnableExperimentalDistributed;
   std::string Description = TargetName.str() + " Attribute";
 #define DECL_ATTR(KEYWORD, NAME, ...)                                          \
   if (canUseAttributeOnDecl(DAK_##NAME, IsInSil, IsConcurrencyEnabled,         \
-                            IsDistributedEnabled, DK))                         \
+                            DK))                         \
     addDeclAttrKeyword(#KEYWORD, Description);
 #include "swift/AST/Attr.def"
 }

lib/Parse/ParseDecl.cpp

@@ -1987,14 +1987,6 @@ bool Parser::parseNewDeclAttribute(DeclAttributes &Attributes, SourceLoc AtLoc,
     DiscardAttribute = true;
   }
 
-  // If this attribute is only permitted when distributed is enabled, reject it.
-  if (DeclAttribute::isDistributedOnly(DK) &&
-      !shouldParseExperimentalDistributed()) {
-    diagnose(Loc, diag::attr_requires_distributed, AttrName,
-             DeclAttribute::isDeclModifier(DK));
-    DiscardAttribute = true;
-  }
-
   if (Context.LangOpts.Target.isOSBinFormatCOFF()) {
     if (DK == DAK_WeakLinked) {
       diagnose(Loc, diag::attr_unsupported_on_target, AttrName,

stdlib/public/Distributed/CMakeLists.txt

@@ -35,7 +35,6 @@ add_swift_target_library(swift_Distributed ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} I
   SWIFT_COMPILE_FLAGS
     ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
     -parse-stdlib
-    -Xfrontend -enable-experimental-distributed
   LINK_FLAGS "${SWIFT_RUNTIME_SWIFT_LINK_FLAGS}"
 
   SWIFT_MODULE_DEPENDS _Concurrency

test/Distributed/Runtime/distributed_actor_decode.swift

@@ -1,4 +1,4 @@
-// RUN: %target-run-simple-swift(-Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -parse-as-library) | %FileCheck %s
+// RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking -parse-as-library) | %FileCheck %s
 
 // REQUIRES: executable_test
 // REQUIRES: concurrency

test/Distributed/Runtime/distributed_actor_deinit.swift

@@ -1,4 +1,4 @@
-// RUN: %target-run-simple-swift(-Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -parse-as-library) | %FileCheck %s
+// RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking -parse-as-library) | %FileCheck %s
 
 // REQUIRES: executable_test
 // REQUIRES: concurrency

test/Distributed/Runtime/distributed_actor_func_calls_remoteCall_echo.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend-emit-module -emit-module-path %t/FakeDistributedActorSystems.swiftmodule -module-name FakeDistributedActorSystems -disable-availability-checking %S/../Inputs/FakeDistributedActorSystems.swift
-// RUN: %target-build-swift -module-name main -Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
+// RUN: %target-build-swift -module-name main  -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s --color
 
 // REQUIRES: executable_test

test/Distributed/Runtime/distributed_actor_func_calls_remoteCall_empty.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend-emit-module -emit-module-path %t/FakeDistributedActorSystems.swiftmodule -module-name FakeDistributedActorSystems -disable-availability-checking %S/../Inputs/FakeDistributedActorSystems.swift
-// RUN: %target-build-swift -module-name main -Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
+// RUN: %target-build-swift -module-name main  -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s --color
 
 // REQUIRES: executable_test

test/Distributed/Runtime/distributed_actor_func_calls_remoteCall_genericFunc.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend-emit-module -emit-module-path %t/FakeDistributedActorSystems.swiftmodule -module-name FakeDistributedActorSystems -disable-availability-checking %S/../Inputs/FakeDistributedActorSystems.swift
-// RUN: %target-build-swift -module-name main -Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
+// RUN: %target-build-swift -module-name main  -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s --color
 
 // REQUIRES: executable_test

test/Distributed/Runtime/distributed_actor_func_calls_remoteCall_hello.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend-emit-module -emit-module-path %t/FakeDistributedActorSystems.swiftmodule -module-name FakeDistributedActorSystems -disable-availability-checking %S/../Inputs/FakeDistributedActorSystems.swift
-// RUN: %target-build-swift -module-name main -Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
+// RUN: %target-build-swift -module-name main  -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s --color
 
 // REQUIRES: executable_test

test/Distributed/Runtime/distributed_actor_func_calls_remoteCall_take.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend-emit-module -emit-module-path %t/FakeDistributedActorSystems.swiftmodule -module-name FakeDistributedActorSystems -disable-availability-checking %S/../Inputs/FakeDistributedActorSystems.swift
-// RUN: %target-build-swift -module-name main -Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
+// RUN: %target-build-swift -module-name main  -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s --color
 
 // REQUIRES: executable_test

test/Distributed/Runtime/distributed_actor_func_calls_remoteCall_takeThrowReturn.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend-emit-module -emit-module-path %t/FakeDistributedActorSystems.swiftmodule -module-name FakeDistributedActorSystems -disable-availability-checking %S/../Inputs/FakeDistributedActorSystems.swift
-// RUN: %target-build-swift -module-name main -Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
+// RUN: %target-build-swift -module-name main  -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s --color
 
 // REQUIRES: executable_test

test/Distributed/Runtime/distributed_actor_func_calls_remoteCall_take_two.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend-emit-module -emit-module-path %t/FakeDistributedActorSystems.swiftmodule -module-name FakeDistributedActorSystems -disable-availability-checking %S/../Inputs/FakeDistributedActorSystems.swift
-// RUN: %target-build-swift -module-name main -Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
+// RUN: %target-build-swift -module-name main  -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s --color
 
 // REQUIRES: executable_test

test/Distributed/Runtime/distributed_actor_func_calls_remoteCall_throw.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend-emit-module -emit-module-path %t/FakeDistributedActorSystems.swiftmodule -module-name FakeDistributedActorSystems -disable-availability-checking %S/../Inputs/FakeDistributedActorSystems.swift
-// RUN: %target-build-swift -module-name main -Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
+// RUN: %target-build-swift -module-name main  -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s --color
 
 // REQUIRES: executable_test

test/Distributed/Runtime/distributed_actor_init_local.swift

@@ -1,4 +1,4 @@
-// RUN: %target-run-simple-swift(-Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -parse-as-library) | %FileCheck %s
+// RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking -parse-as-library) | %FileCheck %s
 
 // REQUIRES: executable_test
 // REQUIRES: concurrency

test/Distributed/Runtime/distributed_actor_isRemote.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend-emit-module -emit-module-path %t/FakeDistributedActorSystems.swiftmodule -module-name FakeDistributedActorSystems -disable-availability-checking %S/../Inputs/FakeDistributedActorSystems.swift
-// RUN: %target-build-swift -module-name main -Xfrontend -enable-experimental-distributed -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
+// RUN: %target-build-swift -module-name main  -Xfrontend -disable-availability-checking -j2 -parse-as-library -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -o %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s --color
 
 // REQUIRES: executable_test