[PATCH 01/12] Remove delete_longjmp_breakpoint_cleanup

[Tom Tromey <tom at tromey dot com>]

This removes delete_longjmp_breakpoint_cleanup in favor of a new
cleanup function type.  This new type is somewhat generic, and will be
reused in subsequent patches.

Note that cleanup_function::cancel was purposely not named "reset".
An earlier version did this, but it was too easy to mistake
cleanup_function::reset and gdb::optional::reset, as pointed out by
Andrew Burgess when reviewing an earlier version of this series.

gdb/ChangeLog
2019-01-08  Tom Tromey  <tom@tromey.com>

	* common/cleanup-function.h: New file.
	* breakpoint.c (until_break_command): Use
	cleanup_function.
	* infcmd.c (delete_longjmp_breakpoint_cleanup): Remove.
	(until_next_command): Use cleanup_function.
	* inferior.h (delete_longjmp_breakpoint_cleanup): Don't declare.
---
 gdb/ChangeLog                 |  9 +++++
 gdb/breakpoint.c              | 16 ++++++---
 gdb/common/cleanup-function.h | 62 +++++++++++++++++++++++++++++++++++
 gdb/infcmd.c                  | 18 +++++-----
 gdb/inferior.h                |  2 --
 5 files changed, 90 insertions(+), 17 deletions(-)
 create mode 100644 gdb/common/cleanup-function.h

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index d54d496972..24ba4071ff 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -83,6 +83,7 @@
 #include "progspace-and-thread.h"
 #include "common/array-view.h"
 #include "common/gdb_optional.h"
+#include "common/cleanup-function.h"
 
 /* Enums for exception-handling support.  */
 enum exception_event_kind
@@ -11078,7 +11079,6 @@ until_break_command (const char *arg, int from_tty, int anywhere)
   struct gdbarch *frame_gdbarch;
   struct frame_id stack_frame_id;
   struct frame_id caller_frame_id;
-  struct cleanup *old_chain;
   int thread;
   struct thread_info *tp;
   struct until_break_fsm *sm;
@@ -11111,8 +11111,6 @@ until_break_command (const char *arg, int from_tty, int anywhere)
   tp = inferior_thread ();
   thread = tp->global_num;
 
-  old_chain = make_cleanup (null_cleanup, NULL);
-
   /* Note linespec handling above invalidates the frame chain.
      Installing a breakpoint also invalidates the frame chain (as it
      may need to switch threads), so do any frame handling before
@@ -11127,6 +11125,14 @@ until_break_command (const char *arg, int from_tty, int anywhere)
      one.  */
 
   breakpoint_up caller_breakpoint;
+
+  gdb::optional<cleanup_function> lj_deleter;
+  auto lj_deletion_func
+    = [=] ()
+      {
+	delete_longjmp_breakpoint (thread);
+      };
+
   if (frame_id_p (caller_frame_id))
     {
       struct symtab_and_line sal2;
@@ -11141,7 +11147,7 @@ until_break_command (const char *arg, int from_tty, int anywhere)
 						    bp_until);
 
       set_longjmp_breakpoint (tp, caller_frame_id);
-      make_cleanup (delete_longjmp_breakpoint_cleanup, &thread);
+      lj_deleter.emplace (lj_deletion_func);
     }
 
   /* set_momentary_breakpoint could invalidate FRAME.  */
@@ -11164,7 +11170,7 @@ until_break_command (const char *arg, int from_tty, int anywhere)
 			    std::move (caller_breakpoint));
   tp->thread_fsm = &sm->thread_fsm;
 
-  discard_cleanups (old_chain);
+  lj_deleter->cancel ();
 
   proceed (-1, GDB_SIGNAL_DEFAULT);
 }
diff --git a/gdb/common/cleanup-function.h b/gdb/common/cleanup-function.h
new file mode 100644
index 0000000000..89cc6d11c8
--- /dev/null
+++ b/gdb/common/cleanup-function.h
@@ -0,0 +1,62 @@
+/* Copyright (C) 2019 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef COMMON_CLEANUP_FUNCTION_H
+#define COMMON_CLEANUP_FUNCTION_H
+
+#include "common/function-view.h"
+
+/* A cleanup function is one that is run at the end of the current
+   scope.  It is just a function of no arguments.  A cleanup function
+   may be canceled by calling the "cancel" method.  */
+
+class cleanup_function
+{
+public:
+
+  explicit cleanup_function (gdb::function_view<void ()> func)
+    : m_func (func)
+  {
+  }
+
+  DISABLE_COPY_AND_ASSIGN (cleanup_function);
+
+  ~cleanup_function ()
+  {
+    m_func ();
+  }
+
+  /* If this is called, then the wrapped function will not be called
+     on destruction.  */
+  void cancel ()
+  {
+    m_func = do_nothing;
+  }
+
+private:
+
+  /* The function to call.  */
+  gdb::function_view<void ()> m_func;
+
+  /* A helper function that is used as the value of m_func when cancel
+     is called.  */
+  static void do_nothing ()
+  {
+  }
+};
+
+#endif /* COMMON_CLEANUP_FUNCTION_H */
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index 3c3add89ab..5c4c4171c5 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -59,6 +59,7 @@
 #include "top.h"
 #include "interps.h"
 #include "common/gdb_optional.h"
+#include "common/cleanup-function.h"
 #include "source.h"
 
 /* Local functions: */
@@ -947,13 +948,6 @@ nexti_command (const char *count_string, int from_tty)
   step_1 (1, 1, count_string);
 }
 
-void
-delete_longjmp_breakpoint_cleanup (void *arg)
-{
-  int thread = * (int *) arg;
-  delete_longjmp_breakpoint (thread);
-}
-
 /* Data for the FSM that manages the step/next/stepi/nexti
    commands.  */
 
@@ -1517,7 +1511,6 @@ until_next_command (int from_tty)
   struct symtab_and_line sal;
   struct thread_info *tp = inferior_thread ();
   int thread = tp->global_num;
-  struct cleanup *old_chain;
   struct until_next_fsm *sm;
 
   clear_proceed_status (0);
@@ -1556,11 +1549,16 @@ until_next_command (int from_tty)
   tp->control.step_over_calls = STEP_OVER_ALL;
 
   set_longjmp_breakpoint (tp, get_frame_id (frame));
-  old_chain = make_cleanup (delete_longjmp_breakpoint_cleanup, &thread);
+  auto lj_deletion_func
+    = [=] ()
+      {
+	delete_longjmp_breakpoint (thread);
+      };
+  cleanup_function lj_deleter (lj_deletion_func);
 
   sm = new_until_next_fsm (command_interp (), tp->global_num);
   tp->thread_fsm = &sm->thread_fsm;
-  discard_cleanups (old_chain);
+  lj_deleter.cancel ();
 
   proceed ((CORE_ADDR) -1, GDB_SIGNAL_DEFAULT);
 }
diff --git a/gdb/inferior.h b/gdb/inferior.h
index a82df1a52a..c63fa26b08 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -198,8 +198,6 @@ extern void continue_1 (int all_threads);
 
 extern void interrupt_target_1 (int all_threads);
 
-extern void delete_longjmp_breakpoint_cleanup (void *arg);
-
 extern void detach_command (const char *, int);
 
 extern void notice_new_inferior (struct thread_info *, int, int);
-- 
2.17.2