cannot thread-join the current thread

2 files changed, 7 insertions, 0 deletions

diff --git a/src/thread.c b/src/thread.c
index 01d2fd0d6eb..551f3de10e4 100644
--- a/src/thread.c
+++ b/src/thread.c
@@ -852,6 +852,9 @@ It is an error for a thread to try to join itself.  */)
   CHECK_THREAD (thread);
   tstate = XTHREAD (thread);
 
+  if (tstate == current_thread)
+    error ("cannot join current thread");
+
   if (tstate->m_specpdl != NULL)
     flush_stack_call_func (thread_join_callback, tstate);
 
diff --git a/test/automated/threads.el b/test/automated/threads.el
index b1c2af59600..db6aa41d63a 100644
--- a/test/automated/threads.el
+++ b/test/automated/threads.el
@@ -70,6 +70,10 @@
        (and threads-test-global
             (not (thread-alive-p thread)))))))
 
+(ert-deftest threads-join-self ()
+  "cannot thread-join the current thread"
+  (should-error (thread-join (current-thread))))
+
 (defvar threads-test-binding nil)
 
 (defun threads-test-thread2 ()