[PATCH 3/3] gdb: add assertion when marking the remote async flag

[Simon Marchi <simon.marchi@polymtl.ca>]

From: Simon Marchi <simon.marchi@efficios.com>

As reported in bug 30630 [1], we hit a case where the remote target's
async flag is marked while the target is not configured (yet) to work
async.  This should not happen.  It is caught thanks to this assert in
remote_target::wait:

    /* Start by clearing the flag that asks for our wait method to be called,
       we'll mark it again at the end if needed.  If the target is not in
       async mode then the async token should not be marked.  */
    if (target_is_async_p ())
      rs->clear_async_event_handler ();
    else
      gdb_assert (!rs->async_event_handler_marked ());

This is helpful, but I think that we could have caught the problem earlier than
that, at the moment we marked the handler.  Catching problems earlier
makes them easier to debug.

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=30630

Change-Id: I7e229c74b04da82bef6a817d5a676be5cf52e833
---
 gdb/remote.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gdb/remote.c b/gdb/remote.c
index 38d0027dbf9e..7830b5cec33f 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -424,7 +424,10 @@ class remote_state
   }
 
   void mark_async_event_handler ()
-  { ::mark_async_event_handler (m_async_event_handler_token); }
+  {
+    gdb_assert (this->is_async_p ());
+    ::mark_async_event_handler (m_async_event_handler_token);
+  }
 
   void clear_async_event_handler ()
   { ::clear_async_event_handler (m_async_event_handler_token); }
-- 
2.42.0