[Sema] Start propagating @_inheritActorContext(always) attribute to closures

Author: xedin

include/swift/AST/Expr.h

@@ -267,7 +267,7 @@ class alignas(8) Expr : public ASTAllocated<Expr> {
     Kind : 2
   );
 
-  SWIFT_INLINE_BITFIELD(ClosureExpr, AbstractClosureExpr, 1+1+1+1+1+1+1+1,
+  SWIFT_INLINE_BITFIELD(ClosureExpr, AbstractClosureExpr, 1+1+1+1+1+1+1+1+1,
     /// True if closure parameters were synthesized from anonymous closure
     /// variables.
     HasAnonymousClosureVars : 1,
@@ -276,9 +276,11 @@ class alignas(8) Expr : public ASTAllocated<Expr> {
     /// on each member reference.
     ImplicitSelfCapture : 1,
 
-    /// True if this @Sendable async closure parameter should implicitly
-    /// inherit the actor context from where it was formed.
+    /// True if this closure parameter should implicitly inherit the actor
+    /// context from where it was formed.
     InheritActorContext : 1,
+    /// The kind for inheritance - none or always at the moment.
+    InheritActorContextKind : 1,
 
     /// True if this closure's actor isolation behavior was determined by an
     /// \c \@preconcurrency declaration.
@@ -4318,6 +4320,7 @@ class ClosureExpr : public AbstractClosureExpr {
     Bits.ClosureExpr.HasAnonymousClosureVars = false;
     Bits.ClosureExpr.ImplicitSelfCapture = false;
     Bits.ClosureExpr.InheritActorContext = false;
+    Bits.ClosureExpr.InheritActorContextKind = 0;
     Bits.ClosureExpr.IsPassedToSendingParameter = false;
     Bits.ClosureExpr.NoGlobalActorAttribute = false;
     Bits.ClosureExpr.RequiresDynamicIsolationChecking = false;
@@ -4366,8 +4369,29 @@ class ClosureExpr : public AbstractClosureExpr {
     return Bits.ClosureExpr.InheritActorContext;
   }
 
-  void setInheritsActorContext(bool value = true) {
+  /// Whether this closure should _always_ implicitly inherit the actor context
+  /// regardless of whether the isolation parameter is captured or not.
+  bool alwaysInheritsActorContext() const {
+    if (!inheritsActorContext())
+      return false;
+    return getInheritActorIsolationModifier() ==
+           InheritActorContextModifier::Always;
+  }
+
+  void setInheritsActorContext(bool value = true,
+                               InheritActorContextModifier modifier =
+                                   InheritActorContextModifier::None) {
     Bits.ClosureExpr.InheritActorContext = value;
+    Bits.ClosureExpr.InheritActorContextKind = uint8_t(modifier);
+    assert((static_cast<InheritActorContextModifier>(
+                Bits.ClosureExpr.InheritActorContextKind) == modifier) &&
+           "not enough bits for modifier");
+  }
+
+  InheritActorContextModifier getInheritActorIsolationModifier() const {
+    assert(inheritsActorContext());
+    return static_cast<InheritActorContextModifier>(
+        Bits.ClosureExpr.InheritActorContextKind);
   }
 
   /// Whether the closure's concurrency behavior was determined by an

include/swift/AST/Types.h

@@ -4049,6 +4049,7 @@ struct ParameterListInfo {
   SmallBitVector propertyWrappers;
   SmallBitVector implicitSelfCapture;
   SmallBitVector inheritActorContext;
+  SmallBitVector alwaysInheritActorContext;
   SmallBitVector variadicGenerics;
   SmallBitVector sendingParameters;
 
@@ -4075,7 +4076,8 @@ struct ParameterListInfo {
 
   /// Whether the given parameter is a closure that should inherit the
   /// actor context from the context in which it was created.
-  bool inheritsActorContext(unsigned paramIdx) const;
+  std::pair<bool, InheritActorContextModifier>
+  inheritsActorContext(unsigned paramIdx) const;
 
   bool isVariadicGenericParameter(unsigned paramIdx) const;
 

lib/AST/Type.cpp

@@ -1378,6 +1378,7 @@ ParameterListInfo::ParameterListInfo(
   propertyWrappers.resize(params.size());
   implicitSelfCapture.resize(params.size());
   inheritActorContext.resize(params.size());
+  alwaysInheritActorContext.resize(params.size());
   variadicGenerics.resize(params.size());
   sendingParameters.resize(params.size());
 
@@ -1434,8 +1435,13 @@ ParameterListInfo::ParameterListInfo(
       implicitSelfCapture.set(i);
     }
 
-    if (param->getAttrs().hasAttribute<InheritActorContextAttr>()) {
-      inheritActorContext.set(i);
+    if (auto *attr =
+            param->getAttrs().getAttribute<InheritActorContextAttr>()) {
+      if (attr->isAlways()) {
+        alwaysInheritActorContext.set(i);
+      } else {
+        inheritActorContext.set(i);
+      }
     }
 
     if (param->getInterfaceType()->is<PackExpansionType>()) {
@@ -1469,10 +1475,18 @@ bool ParameterListInfo::isImplicitSelfCapture(unsigned paramIdx) const {
       : false;
 }
 
-bool ParameterListInfo::inheritsActorContext(unsigned paramIdx) const {
-  return paramIdx < inheritActorContext.size()
-      ? inheritActorContext[paramIdx]
-      : false;
+std::pair<bool, InheritActorContextModifier>
+ParameterListInfo::inheritsActorContext(unsigned paramIdx) const {
+  if (paramIdx >= inheritActorContext.size())
+    return std::make_pair(false, InheritActorContextModifier::None);
+
+  if (inheritActorContext[paramIdx])
+    return std::make_pair(true, InheritActorContextModifier::None);
+
+  if (alwaysInheritActorContext[paramIdx])
+    return std::make_pair(true, InheritActorContextModifier::Always);
+
+  return std::make_pair(false, InheritActorContextModifier::None);
 }
 
 bool ParameterListInfo::isVariadicGenericParameter(unsigned paramIdx) const {

lib/Sema/CSApply.cpp

@@ -6097,35 +6097,35 @@ static bool hasCurriedSelf(ConstraintSystem &cs, ConcreteDeclRef callee,
 }
 
 /// Apply the contextually Sendable flag to the given expression,
-static void applyContextualClosureFlags(Expr *expr, bool implicitSelfCapture,
-                                        bool inheritActorContext,
-                                        bool isPassedToSendingParameter,
+static void applyContextualClosureFlags(Expr *expr, unsigned paramIdx,
+                                        const ParameterListInfo &paramInfo,
                                         bool requiresDynamicIsolationChecking,
                                         bool isMacroArg) {
   if (auto closure = dyn_cast<ClosureExpr>(expr)) {
-    closure->setAllowsImplicitSelfCapture(implicitSelfCapture);
-    closure->setInheritsActorContext(inheritActorContext);
-    closure->setIsPassedToSendingParameter(isPassedToSendingParameter);
+    closure->setAllowsImplicitSelfCapture(
+        paramInfo.isImplicitSelfCapture(paramIdx));
+
+    auto [inheritActorContext, modifier] =
+        paramInfo.inheritsActorContext(paramIdx);
+    closure->setInheritsActorContext(inheritActorContext, modifier);
+
+    closure->setIsPassedToSendingParameter(
+        paramInfo.isSendingParameter(paramIdx));
     closure->setRequiresDynamicIsolationChecking(
         requiresDynamicIsolationChecking);
     closure->setIsMacroArgument(isMacroArg);
     return;
   }
 
   if (auto captureList = dyn_cast<CaptureListExpr>(expr)) {
-    applyContextualClosureFlags(captureList->getClosureBody(),
-                                implicitSelfCapture, inheritActorContext,
-                                isPassedToSendingParameter,
-                                requiresDynamicIsolationChecking,
+    applyContextualClosureFlags(captureList->getClosureBody(), paramIdx,
+                                paramInfo, requiresDynamicIsolationChecking,
                                 isMacroArg);
   }
 
   if (auto identity = dyn_cast<IdentityExpr>(expr)) {
-    applyContextualClosureFlags(identity->getSubExpr(), implicitSelfCapture,
-                                inheritActorContext,
-                                isPassedToSendingParameter,
-                                requiresDynamicIsolationChecking,
-                                isMacroArg);
+    applyContextualClosureFlags(identity->getSubExpr(), paramIdx, paramInfo,
+                                requiresDynamicIsolationChecking, isMacroArg);
   }
 }
 
@@ -6251,19 +6251,13 @@ ArgumentList *ExprRewriter::coerceCallArguments(
 
   auto applyFlagsToArgument = [&paramInfo,
                                &closuresRequireDynamicIsolationChecking,
-                               &locator](
-                                  unsigned paramIdx, Expr *argument) {
+                               &locator](unsigned paramIdx, Expr *argument) {
     if (!isClosureLiteralExpr(argument))
       return;
 
-    bool isImplicitSelfCapture = paramInfo.isImplicitSelfCapture(paramIdx);
-    bool inheritsActorContext = paramInfo.inheritsActorContext(paramIdx);
-    bool isPassedToSendingParameter = paramInfo.isSendingParameter(paramIdx);
     bool isMacroArg = isExpr<MacroExpansionExpr>(locator.getAnchor());
 
-    applyContextualClosureFlags(argument, isImplicitSelfCapture,
-                                inheritsActorContext,
-                                isPassedToSendingParameter,
+    applyContextualClosureFlags(argument, paramIdx, paramInfo,
                                 closuresRequireDynamicIsolationChecking,
                                 isMacroArg);
   };

lib/Sema/TypeCheckConcurrency.cpp

@@ -4774,6 +4774,11 @@ ActorIsolation ActorIsolationChecker::determineClosureIsolation(
 
     case ActorIsolation::ActorInstance: {
       if (checkIsolatedCapture) {
+        auto *explicitClosure = dyn_cast<ClosureExpr>(closure);
+        // @_inheritActorContext(always) forces the isolation capture.
+        if (explicitClosure && explicitClosure->alwaysInheritsActorContext())
+          return parentIsolation;
+
         if (auto param = closure->getCaptureInfo().getIsolatedParamCapture())
           return ActorIsolation::forActorInstanceCapture(param);
       } else {

test/Concurrency/actor_isolation.swift

@@ -1210,6 +1210,8 @@ actor MyServer : Server {
 func acceptAsyncSendableClosure<T>(_: @Sendable () async -> T) { }
 @available(SwiftStdlib 5.1, *)
 func acceptAsyncSendableClosureInheriting<T>(@_inheritActorContext _: @Sendable () async -> T) { }
+@available(SwiftStdlib 5.1, *)
+func acceptAsyncSendableClosureInheritingAlways<T>(@_inheritActorContext(always) _: @Sendable () async -> T) { }
 
 @available(SwiftStdlib 5.1, *)
 extension MyActor {
@@ -1237,6 +1239,10 @@ extension MyActor {
       _ = await synchronous() // expected-warning{{no 'async' operations occur within 'await' expression}}
       counter += 1 // okay
     }
+
+    acceptAsyncSendableClosureInheritingAlways {
+      counter += 1 // Ok
+    }
   }
 }
 
@@ -1257,6 +1263,32 @@ func testGlobalActorInheritance() {
   acceptAsyncSendableClosureInheriting {
     counter += 1 // ok
   }
+
+  acceptAsyncSendableClosureInheritingAlways {
+    counter += 1 // ok
+  }
+}
+
+@available(SwiftStdlib 5.1, *)
+func testIsolatedParameter1(_: isolated any Actor, v: inout Int) {
+  acceptAsyncSendableClosureInheriting {
+    v += 1 // expected-warning {{mutable capture of 'inout' parameter 'v' is not allowed in concurrently-executing code}}
+  }
+
+  acceptAsyncSendableClosureInheritingAlways {
+    v += 1 // Ok
+  }
+}
+
+@available(SwiftStdlib 5.1, *)
+func testIsolatedParameter2(_: isolated (any Actor)? = #isolation, v: inout Int) {
+  acceptAsyncSendableClosureInheriting {
+    v += 1 // expected-warning {{mutable capture of 'inout' parameter 'v' is not allowed in concurrently-executing code}}
+  }
+
+  acceptAsyncSendableClosureInheritingAlways {
+    v += 1 // Ok
+  }
 }
 
 @available(SwiftStdlib 5.1, *)
@@ -1763,4 +1795,4 @@ actor UserDefinedActorSelfDotMethod {
     // error message changes with InferSendabaleFromCaptures - see actor_isolation_swift6.swift
     return functionRef // expected-error {{cannot convert return expression of type '(isolated Self) -> () -> ()' to return type '(UserDefinedActorSelfDotMethod) -> @isolated(any) () -> Void'}}
   }
-}
+}