Convert observers to C++

This converts observers from using a special source-generating script
to be plain C++.  This version of the patch takes advantage of C++11
by using std::function and variadic templates; incorporates Pedro's
patches; and renames the header file to "observable.h" (this change
eliminates the need for a clean rebuild).

Note that Pedro's patches used a template lambda in tui-hooks.c, but
this failed to compile on some buildbot instances (presumably due to
differing C++ versions); I replaced this with an ordinary template
function.

Regression tested on the buildbot.

gdb/ChangeLog
2018-03-19  Pedro Alves  <palves@redhat.com>
	    Tom Tromey  <tom@tromey.com>

	* unittests/observable-selftests.c: New file.
	* common/observable.h: New file.
	* observable.h: New file.
	* ada-lang.c, ada-tasks.c, agent.c, aix-thread.c, annotate.c,
	arm-tdep.c, auto-load.c, auxv.c, break-catch-syscall.c,
	breakpoint.c, bsd-uthread.c, cli/cli-interp.c, cli/cli-setshow.c,
	corefile.c, dummy-frame.c, event-loop.c, event-top.c, exec.c,
	extension.c, frame.c, gdbarch.c, guile/scm-breakpoint.c,
	infcall.c, infcmd.c, inferior.c, inflow.c, infrun.c, jit.c,
	linux-tdep.c, linux-thread-db.c, m68klinux-tdep.c,
	mi/mi-cmd-break.c, mi/mi-interp.c, mi/mi-main.c, objfiles.c,
	ppc-linux-nat.c, ppc-linux-tdep.c, printcmd.c, procfs.c,
	python/py-breakpoint.c, python/py-finishbreakpoint.c,
	python/py-inferior.c, python/py-unwind.c, ravenscar-thread.c,
	record-btrace.c, record-full.c, record.c, regcache.c, remote.c,
	riscv-tdep.c, sol-thread.c, solib-aix.c, solib-spu.c, solib.c,
	spu-multiarch.c, spu-tdep.c, stack.c, symfile-mem.c, symfile.c,
	symtab.c, thread.c, top.c, tracepoint.c, tui/tui-hooks.c,
	tui/tui-interp.c, valops.c: Update all users.
	* tui/tui-hooks.c (tui_bp_created_observer)
	(tui_bp_deleted_observer, tui_bp_modified_observer)
	(tui_inferior_exit_observer, tui_before_prompt_observer)
	(tui_normal_stop_observer, tui_register_changed_observer):
	Remove.
	(tui_observers_token): New global.
	(attach_or_detach, tui_attach_detach_observers): New functions.
	(tui_install_hooks, tui_remove_hooks): Use
	tui_attach_detach_observers.
	* record-btrace.c (record_btrace_thread_observer): Remove.
	(record_btrace_thread_observer_token): New global.
	* observer.sh: Remove.
	* observer.c: Rename to observable.c.
	* observable.c (namespace gdb_observers): Define new objects.
	(observer_debug): Move into gdb_observers namespace.
	(struct observer, struct observer_list, xalloc_observer_list_node)
	(xfree_observer_list_node, generic_observer_attach)
	(generic_observer_detach, generic_observer_notify): Remove.
	(_initialize_observer): Update.
	Don't include observer.inc.
	* Makefile.in (generated_files): Remove observer.h, observer.inc.
	(clean mostlyclean): Likewise.
	(observer.h, observer.inc): Remove targets.
	(SUBDIR_UNITTESTS_SRCS): Add observable-selftests.c.
	(COMMON_SFILES): Use observable.c, not observer.c.
	* .gitignore: Remove observer.h.

gdb/doc/ChangeLog
2018-03-19  Tom Tromey  <tom@tromey.com>

	* observer.texi: Remove.

gdb/testsuite/ChangeLog
2018-03-19  Tom Tromey  <tom@tromey.com>

	* gdb.gdb/observer.exp: Remove.

2 files changed, 4 insertions, 313 deletions

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index dca13c6..2441f15 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,7 @@
+2018-03-19  Tom Tromey  <tom@tromey.com>
+
+	* observer.texi: Remove.
+
 2018-03-04  John Baldwin  <jhb@FreeBSD.org>
 
 	* gdb.texinfo (Debugging Output): Document "set/show debug
diff --git a/gdb/doc/observer.texi b/gdb/doc/observer.texi
deleted file mode 100644
index 8ab8da7..0000000
--- a/gdb/doc/observer.texi
+++ /dev/null
@@ -1,313 +0,0 @@
-@c -*-texinfo-*-
-
-@c This file is part of the GDB manual.
-@c
-@c Copyright (C) 2003-2018 Free Software Foundation, Inc.
-@c
-@c See the file gdbint.texinfo for copying conditions.
-@c
-@c Also, the @deftypefun lines from this file are processed into a
-@c header file during the GDB build process.  Permission is granted
-@c to redistribute and/or modify those lines under the terms of the
-@c GNU General Public License as published by the Free Software
-@c Foundation; either version 3 of the License, or (at your option)
-@c any later version.
-
-@node GDB Observers
-@appendix @value{GDBN} Currently available observers
-
-@section Implementation rationale
-@cindex observers implementation rationale
-
-An @dfn{observer} is an entity which is interested in being notified
-when GDB reaches certain states, or certain events occur in GDB.
-The entity being observed is called the @dfn{subject}.  To receive
-notifications, the observer attaches a callback to the subject.
-One subject can have several observers.
-
-@file{observer.c} implements an internal generic low-level event
-notification mechanism.  This generic event notification mechanism is
-then re-used to implement the exported high-level notification
-management routines for all possible notifications.
-
-The current implementation of the generic observer provides support
-for contextual data.  This contextual data is given to the subject
-when attaching the callback.  In return, the subject will provide
-this contextual data back to the observer as a parameter of the
-callback.
-
-Note that the current support for the contextual data is only partial,
-as it lacks a mechanism that would deallocate this data when the
-callback is detached.  This is not a problem so far, as this contextual
-data is only used internally to hold a function pointer.  Later on, if
-a certain observer needs to provide support for user-level contextual
-data, then the generic notification mechanism will need to be
-enhanced to allow the observer to provide a routine to deallocate the
-data when attaching the callback.
-
-The observer implementation is also currently not reentrant.
-In particular, it is therefore not possible to call the attach
-or detach routines during a notification.
-
-@section Debugging
-Observer notifications can be traced using the command @samp{set debug
-observer 1} (@pxref{Debugging Output, , Optional messages about
-internal happenings, gdb, Debugging with @var{GDBN}}).
-
-@section @code{normal_stop} Notifications
-@cindex @code{normal_stop} observer
-@cindex notification about inferior execution stop
-
-@value{GDBN} notifies all @code{normal_stop} observers when the
-inferior execution has just stopped, the associated messages and
-annotations have been printed, and the control is about to be returned
-to the user.
-
-Note that the @code{normal_stop} notification is not emitted when
-the execution stops due to a breakpoint, and this breakpoint has
-a condition that is not met.  If the breakpoint has any associated
-commands list, the commands are executed after the notification
-is emitted.
-
-The following interfaces are available to manage observers:
-
-@deftypefun extern struct observer *observer_attach_@var{event} (observer_@var{event}_ftype *@var{f})
-Using the function @var{f}, create an observer that is notified when
-ever @var{event} occurs, return the observer.
-@end deftypefun
-
-@deftypefun extern void observer_detach_@var{event} (struct observer *@var{observer});
-Remove @var{observer} from the list of observers to be notified when
-@var{event} occurs.
-@end deftypefun
-
-@deftypefun extern void observer_notify_@var{event} (void);
-Send a notification to all @var{event} observers.
-@end deftypefun
-
-The following observable events are defined:
-
-@deftypefun void normal_stop (struct bpstats *@var{bs}, int @var{print_frame})
-The inferior has stopped for real.  The  @var{bs} argument describes
-the breakpoints were are stopped at, if any.  Second argument
-@var{print_frame} non-zero means display the location where the
-inferior has stopped.
-@end deftypefun
-
-@deftypefun void signal_received (enum gdb_signal @var{siggnal})
-The inferior was stopped by a signal.
-@end deftypefun
-
-@deftypefun void end_stepping_range (void)
-We are done with a step/next/si/ni command.
-@end deftypefun
-
-@deftypefun void signal_exited (enum gdb_signal @var{siggnal})
-The inferior was terminated by a signal.
-@end deftypefun
-
-@deftypefun void exited (int @var{exitstatus})
-The inferior program is finished.
-@end deftypefun
-
-@deftypefun void no_history (void)
-Reverse execution: target ran out of history info.
-@end deftypefun
-
-@deftypefun void sync_execution_done (void)
-A synchronous command finished.
-@end deftypefun
-
-@deftypefun void command_error (void)
-An error was caught while executing a command.
-@end deftypefun
-
-@deftypefun void target_changed (struct target_ops *@var{target})
-The target's register contents have changed.
-@end deftypefun
-
-@deftypefun void executable_changed (void)
-The executable being debugged by GDB has changed: The user decided
-to debug a different program, or the program he was debugging has
-been modified since being loaded by the debugger (by being recompiled,
-for instance).
-@end deftypefun
-
-@deftypefun void inferior_created (struct target_ops *@var{objfile}, int @var{from_tty})
-@value{GDBN} has just connected to an inferior.  For @samp{run},
-@value{GDBN} calls this observer while the inferior is still stopped
-at the entry-point instruction.  For @samp{attach} and @samp{core},
-@value{GDBN} calls this observer immediately after connecting to the
-inferior, and before any information on the inferior has been printed.
-@end deftypefun
-
-@deftypefun void record_changed (struct inferior *@var{inferior}, int @var{started}, const char *@var{method}, const char *@var{format})
-The status of process record for inferior @var{inferior} in
-@value{GDBN} has changed.  The process record is started if
-@var{started} is true, and the process record is stopped if
-@var{started} is false.
-
-When @var{started} is true, @var{method} indicates the short name of the method
-used for recording.  If the method supports multiple formats, @var{format}
-indicates which one is being used, otherwise it is NULL.  When @var{started} is
-false, they are both NULL.
-@end deftypefun
-
-@deftypefun void solib_loaded (struct so_list *@var{solib})
-The shared library specified by @var{solib} has been loaded.  Note that
-when @value{GDBN} calls this observer, the library's symbols probably
-haven't been loaded yet.
-@end deftypefun
-
-@deftypefun void solib_unloaded (struct so_list *@var{solib})
-The shared library specified by @var{solib} has been unloaded.
-Note that when @value{GDBN} calls this observer, the library's
-symbols have not been unloaded yet, and thus are still available.
-@end deftypefun
-
-@deftypefun void new_objfile (struct objfile *@var{objfile})
-The symbol file specified by @var{objfile} has been loaded.
-Called with @var{objfile} equal to @code{NULL} to indicate
-previously loaded symbol table data has now been invalidated.
-@end deftypefun
-
-@deftypefun void free_objfile (struct objfile *@var{objfile})
-The object file specified by @var{objfile} is about to be freed.
-@end deftypefun
-
-@deftypefun void new_thread (struct thread_info *@var{t})
-The thread specified by @var{t} has been created.
-@end deftypefun
-
-@deftypefun void thread_exit (struct thread_info *@var{t}, int @var{silent})
-The thread specified by @var{t} has exited.  The @var{silent} argument
-indicates that @value{GDBN} is removing the thread from its tables
-without wanting to notify the user about it.
-@end deftypefun
-
-@deftypefun void thread_stop_requested (ptid_t @var{ptid})
-An explicit stop request was issued to @var{ptid}.  If @var{ptid}
-equals @var{minus_one_ptid}, the request applied to all threads.  If
-@code{ptid_is_pid(ptid)} returns true, the request applied to all
-threads of the process pointed at by @var{ptid}.  Otherwise, the
-request applied to the single thread pointed at by @var{ptid}.
-@end deftypefun
-
-@deftypefun void target_resumed (ptid_t @var{ptid})
-The target was resumed.  The @var{ptid} parameter specifies which
-thread was resume, and may be RESUME_ALL if all threads are resumed.
-@end deftypefun
-
-@deftypefun void about_to_proceed (void)
-The target is about to be proceeded.
-@end deftypefun
-
-@deftypefun void breakpoint_created (struct breakpoint *@var{b})
-A new breakpoint @var{b} has been created.
-@end deftypefun
-
-@deftypefun void breakpoint_deleted (struct breakpoint *@var{b})
-A breakpoint has been destroyed.  The argument @var{b} is the
-pointer to the destroyed breakpoint.
-@end deftypefun
-
-@deftypefun void breakpoint_modified (struct breakpoint *@var{b})
-A breakpoint has been modified in some way.  The argument @var{b}
-is the modified breakpoint.
-@end deftypefun
-
-@deftypefun void traceframe_changed (int @var{tfnum}, int @var{tpnum})
-The trace frame is changed to @var{tfnum} (e.g., by using the
-@code{tfind} command).  If @var{tfnum} is negative, it means
-@value{GDBN} resumes live debugging.  The number of the tracepoint
-associated with this traceframe is @var{tpnum}.
-@end deftypefun
-
-@deftypefun void architecture_changed (struct gdbarch *@var{newarch})
-The current architecture has changed.  The argument @var{newarch} is
-a pointer to the new architecture.
-@end deftypefun
-
-@deftypefun void thread_ptid_changed (ptid_t @var{old_ptid}, ptid_t @var{new_ptid})
-The thread's ptid has changed.  The @var{old_ptid} parameter specifies
-the old value, and @var{new_ptid} specifies the new value.
-@end deftypefun
-
-@deftypefun void inferior_added (struct inferior *@var{inf})
-The inferior @var{inf} has been added to the list of inferiors.  At
-this point, it might not be associated with any process.
-@end deftypefun
-
-@deftypefun void inferior_appeared (struct inferior *@var{inf})
-The inferior identified by @var{inf} has been attached to a process.
-@end deftypefun
-
-@deftypefun void inferior_exit (struct inferior *@var{inf})
-Either the inferior associated with @var{inf} has been detached from the
-process, or the process has exited.
-@end deftypefun
-
-@deftypefun void inferior_removed (struct inferior *@var{inf})
-The inferior @var{inf} has been removed from the list of inferiors.
-This method is called immediately before freeing @var{inf}.
-@end deftypefun
-
-@deftypefun void memory_changed (struct inferior *@var{inferior}, CORE_ADDR @var{addr}, ssize_t @var{len}, const bfd_byte *@var{data})
-Bytes from @var{data} to @var{data} + @var{len} have been written
-to the @var{inferior} at @var{addr}.
-@end deftypefun
-
-@deftypefun void before_prompt (const char *@var{current_prompt})
-Called before a top-level prompt is displayed.  @var{current_prompt} is
-the current top-level prompt.
-@end deftypefun
-
-@deftypefun void gdb_datadir_changed (void)
-Variable gdb_datadir has been set.  The value may not necessarily change.
-@end deftypefun
-
-@deftypefun void command_param_changed (const char *@var{param}, const char *@var{value})
-The parameter of some @code{set} commands in console are changed.  This
-method is called after a command @code{set @var{param} @var{value}}.
-@var{param} is the parameter of @code{set} command, and @var{value}
-is the value of changed parameter.
-@end deftypefun
-
-@deftypefun void tsv_created (const struct trace_state_variable *@var{tsv})
-The new trace state variable @var{tsv} is created.
-@end deftypefun
-
-@deftypefun void tsv_deleted (const struct trace_state_variable *@var{tsv})
-The trace state variable @var{tsv} is deleted.  If @var{tsv} is
-@code{NULL}, all trace state variables are deleted.
-@end deftypefun
-
-@deftypefun void tsv_modified (const struct trace_state_variable *@var{tsv})
-The trace state value @var{tsv} is modified.
-@end deftypefun
-
-@deftypefun void inferior_call_pre (ptid_t @var{thread}, CORE_ADDR @var{address})
-An inferior function at @var{address} is about to be called in thread
-@var{thread}.
-@end deftypefun
-
-@deftypefun void inferior_call_post (ptid_t @var{thread}, CORE_ADDR @var{address})
-The inferior function at @var{address} has just been called.  This observer
-is called even if the inferior exits during the call.  @var{thread} is the
-thread in which the function was called, which may be different from the
-current thread.
-@end deftypefun
-
-@deftypefun void register_changed (struct frame_info *@var{frame}, int @var{regnum})
-A register in the inferior has been modified by the @value{GDBN} user.
-@end deftypefun
-
-@deftypefun void test_notification (int @var{somearg})
-This observer is used for internal testing.  Do not use.  
-See testsuite/gdb.gdb/observer.exp.
-@end deftypefun
-
-@deftypefun void user_selected_context_changed (user_selected_what @var{selection})
-The user-selected inferior, thread and/or frame has changed.  The user_select_what
-flag specifies if the inferior, thread and/or frame has changed.
-@end deftypefun