List checkpoints in ascending order

Before:
     (gdb) info checkpoints
       3 process 29132 at 0x4008ad, file foo.c, line 81
       2 process 29131 at 0x4008ad, file foo.c, line 81
       1 process 29130 at 0x4008ad, file foo.c, line 81
     * 0 Thread 0x7ffff7fc5740 (LWP 29128) (main process) at 0x4008ad, file foo.c, line 81

After:
     (gdb) info checkpoints
     * 0 Thread 0x7ffff7fc5740 (LWP 29128) (main process) at 0x4008ad, file foo.c, line 81
       1 process 29130 at 0x4008ad, file foo.c, line 81
       2 process 29131 at 0x4008ad, file foo.c, line 81
       3 process 29132 at 0x4008ad, file foo.c, line 81

gdb/ChangeLog:
2015-11-24  Pedro Alves  <palves@redhat.com>

	PR 17539
        * printcmd.c (display_command): Append new display at the end of
        the list.

gdb/testsuite/ChangeLog:
2015-11-24  Pedro Alves  <palves@redhat.com>

	PR 17539
        * gdb.base/display.exp: Expect displays to be sorted in ascending
        order.  Use multi_line.
        * gdb.base/solib-display.exp: Likewise.

1 files changed, 30 insertions, 5 deletions

diff --git a/gdb/linux-fork.c b/gdb/linux-fork.c
index 9a469d4625d..786670aedb2 100644
--- a/gdb/linux-fork.c
+++ b/gdb/linux-fork.c
@@ -63,6 +63,21 @@ forks_exist_p (void)
   return (fork_list != NULL);
 }
 
+/* Return the last fork in the list.  */
+
+static struct fork_info *
+find_last_fork (void)
+{
+  struct fork_info *last;
+
+  if (fork_list == NULL)
+    return NULL;
+
+  for (last = fork_list; last->next != NULL; last = last->next)
+    ;
+  return last;
+}
+
 /* Add a fork to the internal fork list.  */
 
 struct fork_info *
@@ -83,8 +98,16 @@ add_fork (pid_t pid)
   fp = XCNEW (struct fork_info);
   fp->ptid = ptid_build (pid, pid, 0);
   fp->num = ++highest_fork_num;
-  fp->next = fork_list;
-  fork_list = fp;
+
+  if (fork_list == NULL)
+    fork_list = fp;
+  else
+    {
+      struct fork_info *last = find_last_fork ();
+
+      last->next = fp;
+    }
+
   return fp;
 }
 
@@ -353,12 +376,13 @@ linux_fork_killall (void)
 void
 linux_fork_mourn_inferior (void)
 {
+  struct fork_info *last;
+  int status;
+
   /* Wait just one more time to collect the inferior's exit status.
      Do not check whether this succeeds though, since we may be
      dealing with a process that we attached to.  Such a process will
      only report its exit status to its original parent.  */
-  int status;
-
   waitpid (ptid_get_pid (inferior_ptid), &status, 0);
 
   /* OK, presumably inferior_ptid is the one who has exited.
@@ -371,7 +395,8 @@ linux_fork_mourn_inferior (void)
      inferior_ptid yet.  */
   gdb_assert (fork_list);
 
-  fork_load_infrun_state (fork_list);
+  last = find_last_fork ();
+  fork_load_infrun_state (last);
   printf_filtered (_("[Switching to %s]\n"),
 		   target_pid_to_str (inferior_ptid));