[RFA] Fix GDB build failure on Windows

[Joel Brobecker <brobecker@adacore.com>]

Hello,

A recent enhancement to use thread_info and inferior pointers more
throughout accidently broke the build in windows-nat.c.  This patch
fixes it by completing the transition for the couple of spots that
were missed.

gdb/ChangeLog:

        * windows-nat.c (windows_delete_thread): Make parameter ptid
        a constant reference.  Fix call to delete_thread.  Log a
        DEBUG_EVENTS message if the thread_info corresponding to
        the given ptid_t could not be found.
        (windows_nat_target::detach): Fix call to detach_inferior.

Tested on x86-windows and x86_64-windows, using AdaCore's testsuite.
OK to apply?

Thanks,
-- 
Joel

---
 gdb/windows-nat.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index 63a7800..620e25c 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -479,7 +479,7 @@ windows_init_thread_list (void)
 
 /* Delete a thread from the list of threads.  */
 static void
-windows_delete_thread (ptid_t ptid, DWORD exit_code)
+windows_delete_thread (const ptid_t &ptid, DWORD exit_code)
 {
   windows_thread_info *th;
   DWORD id;
@@ -493,7 +493,26 @@ windows_delete_thread (ptid_t ptid, DWORD exit_code)
   else if (print_thread_events && id != main_thread_id)
     printf_unfiltered (_("[%s exited with code %u]\n"),
 		       target_pid_to_str (ptid), (unsigned) exit_code);
-  delete_thread (ptid);
+
+  thread_info *tp = find_thread_ptid (ptid);
+  if (tp != NULL)
+    delete_thread (tp);
+  else
+    {
+      /* Something unexpected happened: We are trying to delete
+	 a thread that the core layer apparently does not know about.
+	 This should never happen, and thus we want to be able to
+	 report this discrepancy should it actually happen and have
+	 unanticipated side-effects; but since we were trying to
+	 delete the thread anyway, it's quite possible that this
+	 issue has no actual consequence in terms of the overall
+	 behavior.  So, instead of unnecessarily worrying the user
+	 with a warning or internal-error, just log a DEBUG_EVENTS
+	 event.  */
+      DEBUG_EVENTS (("gdb: windows_delete_thread cannot find thread"
+		     " for ptid (pid=%d, tid=%ld)\n",
+		     ptid.pid(), ptid.tid()));
+    }
 
   for (th = &thread_head;
        th->next != NULL && th->next->id != id;
@@ -2000,7 +2019,7 @@ windows_nat_target::detach (inferior *inf, int from_tty)
 
   x86_cleanup_dregs ();
   inferior_ptid = null_ptid;
-  detach_inferior (current_event.dwProcessId);
+  detach_inferior (current_inferior ());
 
   maybe_unpush_target ();
 }
-- 
2.1.4