--- /dev/null
+// RUN: %clangxx_tsan -O1 %s -o %t && %t 2>&1 | FileCheck %s
+#include <pthread.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+int fd;
+char buf;
+
+void *Thread1(void *x) {
+ buf = 1;
+ sleep(1);
+ return NULL;
+}
+
+void *Thread2(void *x) {
+ write(fd, &buf, 1);
+ return NULL;
+}
+
+int main() {
+ fd = open("/dev/null", O_WRONLY);
+ if (fd < 0) return 1;
+ pthread_t t[2];
+ pthread_create(&t[0], NULL, Thread1, NULL);
+ sleep(1);
+ pthread_create(&t[1], NULL, Thread2, NULL);
+ pthread_join(t[0], NULL);
+ pthread_join(t[1], NULL);
+ close(fd);
+}
+
+// CHECK: WARNING: ThreadSanitizer: data race
+// CHECK: Read of size 1
+// CHECK: #0 write
+// CHECK: Previous write of size 1
+// CHECK: #0 Thread1