1 files changed, 58 insertions, 0 deletions
diff --git a/test/tsan/Darwin/external-dups.cc b/test/tsan/Darwin/external-dups.cc
new file mode 100644
index 000000000000..79432bac4a02
--- /dev/null
+++ b/test/tsan/Darwin/external-dups.cc
@@ -0,0 +1,58 @@
+// RUN: %clangxx_tsan %s -o %t
+// RUN: %deflake %run %t 2>&1 | FileCheck %s
+
+#include <thread>
+
+#import "../test.h"
+
+void *tag;
+
+__attribute__((no_sanitize("thread")))
+void ExternalWrite(void *addr) {
+  __tsan_external_write(addr, __builtin_return_address(0), tag);
+}
+
+int main(int argc, char *argv[]) {
+  barrier_init(&barrier, 2);
+  tag = __tsan_external_register_tag("HelloWorld");
+  fprintf(stderr, "Start.\n");
+  // CHECK: Start.
+   
+  for (int i = 0; i < 4; i++) {
+    void *opaque_object = malloc(16);
+    std::thread t1([opaque_object] {
+      ExternalWrite(opaque_object);
+      barrier_wait(&barrier);
+    });
+    std::thread t2([opaque_object] {
+      barrier_wait(&barrier);
+      ExternalWrite(opaque_object);
+    });
+    // CHECK: WARNING: ThreadSanitizer: race on a library object
+    t1.join();
+    t2.join();
+  }
+  
+  fprintf(stderr, "First phase done.\n");
+  // CHECK: First phase done.
+
+  for (int i = 0; i < 4; i++) {
+    void *opaque_object = malloc(16);
+    std::thread t1([opaque_object] {
+      ExternalWrite(opaque_object);
+      barrier_wait(&barrier);
+    });
+    std::thread t2([opaque_object] {
+      barrier_wait(&barrier);
+      ExternalWrite(opaque_object);
+    });
+    // CHECK: WARNING: ThreadSanitizer: race on a library object
+    t1.join();
+    t2.join();
+  }
+
+  fprintf(stderr, "Second phase done.\n");
+  // CHECK: Second phase done.
+}
+
+// CHECK: ThreadSanitizer: reported 2 warnings