Merge pull request #81881 from hborla/6.2-isolated-capture-fixes

[6.2][Concurrency] Fix a false-positive metatype capture diagnostic.

Author: hborla

lib/Sema/TypeCheckConcurrency.cpp

@@ -2559,7 +2559,8 @@ namespace {
     /// Determine whether code in the given use context might execute
     /// concurrently with code in the definition context.
     bool mayExecuteConcurrentlyWith(
-        const DeclContext *useContext, const DeclContext *defContext);
+        const DeclContext *useContext, const DeclContext *defContext,
+        bool includeSending = false);
 
     /// If the subexpression is a reference to a mutable local variable from a
     /// different context, record its parent. We'll query this as part of
@@ -3067,12 +3068,9 @@ namespace {
         }
       }
 
-      // FIXME: When passing to a sending parameter, should this be handled
-      // by region isolation? Or should it always be handled by region
-      // isolation?
       if (mayExecuteConcurrentlyWith(
-              localFunc.getAsDeclContext(), getDeclContext()) ||
-          (explicitClosure && explicitClosure->isPassedToSendingParameter())) {
+              localFunc.getAsDeclContext(), getDeclContext(),
+              /*includeSending*/true)) {
         auto innermostGenericDC = localFunc.getAsDeclContext();
         while (innermostGenericDC && !innermostGenericDC->isGenericContext())
           innermostGenericDC = innermostGenericDC->getParent();
@@ -4834,13 +4832,12 @@ ActorIsolation ActorIsolationChecker::determineClosureIsolation(
 }
 
 bool ActorIsolationChecker::mayExecuteConcurrentlyWith(
-    const DeclContext *useContext, const DeclContext *defContext) {
+    const DeclContext *useContext, const DeclContext *defContext,
+    bool includeSending) {
   // Fast path for when the use and definition contexts are the same.
   if (useContext == defContext)
     return false;
 
-  bool isolatedStateMayEscape = false;
-
   auto useIsolation = getActorIsolationOfContext(
       const_cast<DeclContext *>(useContext), getClosureActorIsolation);
   if (useIsolation.isActorIsolated()) {
@@ -4858,16 +4855,6 @@ bool ActorIsolationChecker::mayExecuteConcurrentlyWith(
     if (ctx.LangOpts.hasFeature(Feature::GlobalActorIsolatedTypesUsability) &&
         regionIsolationEnabled && useIsolation.isGlobalActor())
       return false;
-
-    // If the local function is not Sendable, its isolation differs
-    // from that of the context, and both contexts are actor isolated,
-    // then capturing non-Sendable values allows the closure to stash
-    // those values into actor isolated state. The original context
-    // may also stash those values into isolated state, enabling concurrent
-    // access later on.
-    isolatedStateMayEscape =
-        (!regionIsolationEnabled &&
-        useIsolation.isActorIsolated() && defIsolation.isActorIsolated());
   }
 
   // Walk the context chain from the use to the definition.
@@ -4877,18 +4864,17 @@ bool ActorIsolationChecker::mayExecuteConcurrentlyWith(
       if (closure->isSendable())
         return true;
 
-      if (isolatedStateMayEscape)
-        return true;
+      if (auto *explicitClosure = dyn_cast<ClosureExpr>(closure)) {
+        if (includeSending && explicitClosure->isPassedToSendingParameter())
+          return true;
+      }
     }
 
     if (auto func = dyn_cast<FuncDecl>(useContext)) {
       if (func->isLocalCapture()) {
         // If the function is @Sendable... it can be run concurrently.
         if (func->isSendable())
           return true;
-
-        if (isolatedStateMayEscape)
-          return true;
       }
     }
 

test/Concurrency/sendable_metatype_typecheck.swift

@@ -175,3 +175,16 @@ extension TestUnapplied {
 func testUnappliedWithOpetator<T: Comparable>(v: TestUnapplied<T>) {
   v<=>(>) // expected-error {{converting non-Sendable function value to '@Sendable (T, T) -> Bool' may introduce data races}}
 }
+
+protocol P {}
+
+func acceptClosure(_: () -> Void) {}
+
+@MainActor
+func f<T: P>(_: T.Type) {
+  acceptClosure {
+    Task {
+      _ = T.self // okay to capture T.Type in this closure.
+    }
+  }
+}