Remove cleanup from frame_prepare_for_sniffer

Currently frame_prepare_for_sniffer returns a cleanup.  This patch
changes it to return void, and exposes frame_cleanup_after_sniffer to
the caller.

Normally I would write an RAII class for this sort of thing; but
because there was just a single caller of frame_prepare_for_sniffer,
and because this caller is already using try/catch, I thought it
seemed ok to require explicit calls in this instance.

Regression tested by the buildbot.

gdb/ChangeLog
2017-10-08  Tom Tromey  <tom@tromey.com>

	* frame-unwind.c (frame_unwind_try_unwinder): Update.
	* frame.h (frame_cleanup_after_sniffer): Declare.
	(frame_prepare_for_sniffer): Return void.
	* frame.c (frame_cleanup_after_sniffer): No longer static.  Change
	type of argument.
	(frame_prepare_for_sniffer): Return void.

1 files changed, 5 insertions, 8 deletions

diff --git a/gdb/frame.c b/gdb/frame.c
index afdc157ebd..17f7397aee 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -2864,11 +2864,9 @@ frame_stop_reason_symbol_string (enum unwind_stop_reason reason)
 /* Clean up after a failed (wrong unwinder) attempt to unwind past
    FRAME.  */
 
-static void
-frame_cleanup_after_sniffer (void *arg)
+void
+frame_cleanup_after_sniffer (struct frame_info *frame)
 {
-  struct frame_info *frame = (struct frame_info *) arg;
-
   /* The sniffer should not allocate a prologue cache if it did not
      match this frame.  */
   gdb_assert (frame->prologue_cache == NULL);
@@ -2893,16 +2891,15 @@ frame_cleanup_after_sniffer (void *arg)
 }
 
 /* Set FRAME's unwinder temporarily, so that we can call a sniffer.
-   Return a cleanup which should be called if unwinding fails, and
-   discarded if it succeeds.  */
+   If sniffing fails, the caller should be sure to call
+   frame_cleanup_after_sniffer.  */
 
-struct cleanup *
+void
 frame_prepare_for_sniffer (struct frame_info *frame,
 			   const struct frame_unwind *unwind)
 {
   gdb_assert (frame->unwind == NULL);
   frame->unwind = unwind;
-  return make_cleanup (frame_cleanup_after_sniffer, frame);
 }
 
 static struct cmd_list_element *set_backtrace_cmdlist;