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.

1 files changed, 8 insertions, 14 deletions

diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index e77a6a7d216..7264b8ed2b6 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -26,7 +26,7 @@
 #include "target.h"
 #include "gdbcmd.h"
 #include "disasm.h"
-#include "observer.h"
+#include "observable.h"
 #include "cli/cli-utils.h"
 #include "source.h"
 #include "ui-out.h"
@@ -44,8 +44,9 @@
 /* The target_ops of record-btrace.  */
 static struct target_ops record_btrace_ops;
 
-/* A new thread observer enabling branch tracing for the new thread.  */
-static struct observer *record_btrace_thread_observer;
+/* Token associated with a new-thread observer enabling branch tracing
+   for the new thread.  */
+static const gdb::observers::token record_btrace_thread_observer_token;
 
 /* Memory access types used in set/show record btrace replay-memory-access.  */
 static const char replay_memory_access_read_only[] = "read-only";
@@ -166,8 +167,8 @@ record_btrace_auto_enable (void)
 {
   DEBUG ("attach thread observer");
 
-  record_btrace_thread_observer
-    = observer_attach_new_thread (record_btrace_enable_warn);
+  gdb::observers::new_thread.attach (record_btrace_enable_warn,
+				     record_btrace_thread_observer_token);
 }
 
 /* Disable automatic tracing of new threads.  */
@@ -175,14 +176,9 @@ record_btrace_auto_enable (void)
 static void
 record_btrace_auto_disable (void)
 {
-  /* The observer may have been detached, already.  */
-  if (record_btrace_thread_observer == NULL)
-    return;
-
   DEBUG ("detach thread observer");
 
-  observer_detach_new_thread (record_btrace_thread_observer);
-  record_btrace_thread_observer = NULL;
+  gdb::observers::new_thread.detach (record_btrace_thread_observer_token);
 }
 
 /* The record-btrace async event handler function.  */
@@ -210,7 +206,7 @@ record_btrace_push_target (void)
   record_btrace_generating_corefile = 0;
 
   format = btrace_format_short_string (record_btrace_conf.format);
-  observer_notify_record_changed (current_inferior (), 1, "btrace", format);
+  gdb::observers::record_changed.notify (current_inferior (), 1, "btrace", format);
 }
 
 /* Disable btrace on a set of threads on scope exit.  */
@@ -258,8 +254,6 @@ record_btrace_open (const char *args, int from_tty)
   if (!target_has_execution)
     error (_("The program is not being run."));
 
-  gdb_assert (record_btrace_thread_observer == NULL);
-
   ALL_NON_EXITED_THREADS (tp)
     if (args == NULL || *args == 0 || number_is_in_list (args, tp->global_num))
       {