Merge branch 'main' into rebranch

Conflicts:
      lib/Basic/Platform.cpp

```
diff --git a/lib/Basic/Platform.cpp b/lib/Basic/Platform.cpp
index 240edfa144a..1797c87635f 100644
--- a/lib/Basic/Platform.cpp
+++ b/lib/Basic/Platform.cpp
@@ -200,10 +200,7 @@ StringRef swift::getPlatformNameForTriple(const llvm::Triple &triple) {
   case llvm::Triple::CUDA:
   case llvm::Triple::DragonFly:
   case llvm::Triple::DriverKit:
-<<<<<<< HEAD
   case llvm::Triple::ELFIAMCU:
-=======
->>>>>>> main
   case llvm::Triple::Emscripten:
   case llvm::Triple::Fuchsia:
   case llvm::Triple::HermitCore:
```

include/swift/Basic/Features.def

@@ -191,6 +191,7 @@ UPCOMING_FEATURE(GlobalConcurrency, 412, 6)
 UPCOMING_FEATURE(InferSendableFromCaptures, 418, 6)
 UPCOMING_FEATURE(ImplicitOpenExistentials, 352, 6)
 UPCOMING_FEATURE(RegionBasedIsolation, 414, 6)
+UPCOMING_FEATURE(DynamicActorIsolation, 423, 6)
 UPCOMING_FEATURE(MoveOnlyPartialConsumption, 429, 6)
 
 // Swift 7
@@ -354,11 +355,6 @@ EXPERIMENTAL_FEATURE(GroupActorErrors, true)
 // Allow for the 'transferring' keyword to be applied to arguments and results.
 EXPERIMENTAL_FEATURE(TransferringArgsAndResults, true)
 
-// Enable `@preconcurrency` attribute on protocol conformances and runtime checks
-// of actor isolation in @obj thunks and arguments of APIs that haven't yet adopted
-// strict concurrency checking.
-EXPERIMENTAL_FEATURE(DynamicActorIsolation, false)
-
 // Allow for `switch` of noncopyable values to be borrowing or consuming.
 EXPERIMENTAL_FEATURE(BorrowingSwitch, true)
 

include/swift/Basic/LangOptions.h

@@ -593,6 +593,9 @@ namespace swift {
     /// type-checking, SIL verification, and IR emission,
     bool BypassResilienceChecks = false;
 
+    /// Disables `DynamicActorIsolation` feature.
+    bool DisableDynamicActorIsolation = false;
+
     /// Whether or not to allow experimental features that are only available
     /// in "production".
 #ifdef NDEBUG
@@ -605,6 +608,11 @@ namespace swift {
       return ActiveConcurrencyModel == ConcurrencyModel::TaskToThread;
     }
 
+    bool isDynamicActorIsolationCheckingEnabled() const {
+      return !DisableDynamicActorIsolation &&
+             hasFeature(Feature::DynamicActorIsolation);
+    }
+
     LangOptions();
 
     /// Sets the target we are building for and updates platform conditions
@@ -627,6 +635,8 @@ namespace swift {
         return Target.getiOSVersion();
       } else if (Target.isWatchOS()) {
         return Target.getOSVersion();
+      } else if (Target.isXROS()) {
+        return Target.getOSVersion();
       }
       return llvm::VersionTuple(/*Major=*/0, /*Minor=*/0, /*Subminor=*/0);
     }

include/swift/Basic/Platform.h

@@ -33,7 +33,9 @@ namespace swift {
     TvOS,
     TvOSSimulator,
     WatchOS,
-    WatchOSSimulator
+    WatchOSSimulator,
+    VisionOS,
+    VisionOSSimulator
   };
 
   /// Returns true if the given triple represents iOS running in a simulator.
@@ -48,6 +50,9 @@ namespace swift {
   /// Returns true if the given triple represents a macCatalyst environment.
   bool tripleIsMacCatalystEnvironment(const llvm::Triple &triple);
 
+  /// Returns true if the given triple represents visionOS running in a simulator.
+  bool tripleIsVisionSimulator(const llvm::Triple &triple);
+
   /// Determine whether the triple infers the "simulator" environment.
   bool tripleInfersSimulatorEnvironment(const llvm::Triple &triple);