[Concurrency] Avoid reinterpret_cast in Concurrency/Task.cpp, fixes crashes in libdispatch

Author: kubamracek

stdlib/public/Concurrency/Task.cpp

@@ -394,7 +394,7 @@ static const unsigned long dispatchSwiftObjectType = 1;
 
 #if !SWIFT_CONCURRENCY_EMBEDDED
 
-FullMetadata<DispatchClassMetadata> jobHeapMetadata = {
+static FullMetadata<DispatchClassMetadata> jobHeapMetadata = {
   {
     {
       /*type layout*/ nullptr,
@@ -433,6 +433,17 @@ static FullMetadata<DispatchClassMetadata> taskHeapMetadata = {
   }
 };
 
+
+const void *const swift::_swift_concurrency_debug_jobMetadata =
+    static_cast<Metadata *>(&jobHeapMetadata);
+const void *const swift::_swift_concurrency_debug_asyncTaskMetadata =
+    static_cast<Metadata *>(&taskHeapMetadata);
+
+const HeapMetadata *swift::jobHeapMetadataPtr =
+    static_cast<HeapMetadata *>(&jobHeapMetadata);
+const HeapMetadata *swift::taskHeapMetadataPtr =
+    static_cast<HeapMetadata *>(&taskHeapMetadata);
+
 #else // SWIFT_CONCURRENCY_EMBEDDED
 
 // This matches the embedded class metadata layout in IRGen and in
@@ -451,8 +462,6 @@ static EmbeddedClassMetadata taskHeapMetadata = {
   0, &destroyTask, 0,
 };
 
-#endif
-
 const void *const swift::_swift_concurrency_debug_jobMetadata =
     (Metadata *)(&jobHeapMetadata);
 const void *const swift::_swift_concurrency_debug_asyncTaskMetadata =
@@ -463,6 +472,8 @@ const HeapMetadata *swift::jobHeapMetadataPtr =
 const HeapMetadata *swift::taskHeapMetadataPtr =
     (HeapMetadata *)(&taskHeapMetadata);
 
+#endif
+
 static void completeTaskImpl(AsyncTask *task,
                              AsyncContext *context,
                              SwiftError *error) {
@@ -986,13 +997,11 @@ swift_task_create_commonImpl(size_t rawTaskCreateFlags,
     // Initialize the refcount bits to "immortal", so that
     // ARC operations don't have any effect on the task.
     task = new (allocation)
-        AsyncTask(reinterpret_cast<ClassMetadata *>(&taskHeapMetadata),
-                  InlineRefCounts::Immortal, jobFlags, function, initialContext,
-                  captureCurrentVoucher);
-  } else {
-    task = new (allocation)
-        AsyncTask(reinterpret_cast<ClassMetadata *>(&taskHeapMetadata), jobFlags,
+        AsyncTask(taskHeapMetadataPtr, InlineRefCounts::Immortal, jobFlags,
                   function, initialContext, captureCurrentVoucher);
+  } else {
+    task = new (allocation) AsyncTask(taskHeapMetadataPtr, jobFlags, function,
+                                      initialContext, captureCurrentVoucher);
   }
 
   // Initialize the child fragment if applicable.