Some get_last_target_status tweaks

- Make get_last_target_status arguments optional.  A following patch
  will add another argument to get_last_target_status (the event's
  target), and passing nullptr when we don't care for some piece of
  info is handier than creating dummy local variables.

- Declare nullify_last_target_wait_ptid in a header, and remove the
  local extern declaration from linux-fork.c.

gdb/ChangeLog:
2020-01-10  Pedro Alves  <palves@redhat.com>

	* break-catch-sig.c (signal_catchpoint_print_it): Don't pass a
	ptid to get_last_target_status.
	* break-catch-syscall.c (print_it_catch_syscall): Don't pass a
	ptid to get_last_target_status.
	* infcmd.c (continue_command): Don't pass a target_waitstatus to
	get_last_target_status.
	(info_program_command): Don't pass a target_waitstatus to
	get_last_target_status.
	* infrun.c (init_wait_for_inferior): Use
	nullify_last_target_wait_ptid.
	(get_last_target_status): Handle nullptr arguments.
	(nullify_last_target_wait_ptid): Clear target_last_waitstatus.
	(print_stop_event): Don't pass a ptid to get_last_target_status.
	(normal_stop): Don't pass a ptid to get_last_target_status.
	* infrun.h (get_last_target_status, set_last_target_status): Move
	comments here and update.
	(nullify_last_target_wait_ptid): Declare.
	* linux-fork.c (fork_load_infrun_state): Remove local extern
	declaration of nullify_last_target_wait_ptid.
	* linux-nat.c (get_detach_signal): Don't pass a target_waitstatus
	to get_last_target_status.

1 files changed, 9 insertions, 0 deletions

diff --git a/gdb/infrun.h b/gdb/infrun.h
index 9125141..4dd995d 100644
--- a/gdb/infrun.h
+++ b/gdb/infrun.h
@@ -101,12 +101,21 @@ extern void wait_for_inferior (void);
    target, false otherwise.  */
 extern int normal_stop (void);
 
+/* Return the cached copy of the last ptid/waitstatus returned
+   by target_wait()/deprecated_target_wait_hook().  The data is
+   actually cached by handle_inferior_event(), which gets called
+   immediately after target_wait()/deprecated_target_wait_hook().  */
 extern void get_last_target_status (ptid_t *ptid,
 				    struct target_waitstatus *status);
 
+/* Set the cached copy of the last ptid/waitstatus.  */
 extern void set_last_target_status (ptid_t ptid,
 				    struct target_waitstatus status);
 
+/* Clear the cached copy of the last ptid/waitstatus returned by
+   target_wait().  */
+extern void nullify_last_target_wait_ptid ();
+
 /* Stop all threads.  Only returns after everything is halted.  */
 extern void stop_all_threads (void);