(backtrace-on-redisplay-error): Use `handler-bind`scratch/handler-bind

Reimplement `backtrace-on-redisplay-error` using `push_handler_bind`.
This moves the code from `signal_or_quit` to `xdisp.c` and
`debug-early.el`.

* lisp/emacs-lisp/debug-early.el (debug-early-backtrace):
Add `base` arg to strip "internal" frames.
(debug--early): New function, extracted from `debug-early`.
(debug-early, debug-early--handler): Use it.
(debug-early--muted): New function, extracted (translated) from
`signal_or_quit`; trim the buffer to a max of 10 backtraces.

* src/xdisp.c (funcall_with_backtraces): New function.
(dsafe_calln): Use it.
(syms_of_xdisp): Defsym `Qdebug_early__muted`.

* src/eval.c (redisplay_deep_handler): Delete var.
(init_eval, internal_condition_case_n): Don't set it any more.
(backtrace_yet): Delete var.
(signal_or_quit): Remove special case for `backtrace_on_redisplay_error`.
* src/keyboard.c (command_loop_1): Don't set `backtrace_yet` any more.
* src/lisp.h (backtrace_yet): Don't declare.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/keyboard.c b/src/keyboard.c
index f10e9fd79b7..447f8d5d4ff 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -1167,9 +1167,10 @@ top_level_2 (void)
      encountering an error, to help with debugging.  */
   bool setup_handler = noninteractive;
   if (setup_handler)
+    /* FIXME: Should we (re)use `list_of_error` from `xdisp.c`? */
     push_handler_bind (list1 (Qerror), Qdebug_early__handler, 0);
 
-  Lisp_Object res = Feval (Vtop_level, Qnil);
+  Lisp_Object res = Feval (Vtop_level, Qt);
 
   if (setup_handler)
     pop_handler ();
@@ -1365,7 +1366,6 @@ command_loop_1 (void)
         display_malloc_warning ();
 
       Vdeactivate_mark = Qnil;
-      backtrace_yet = false;
 
       /* Don't ignore mouse movements for more than a single command
          loop.  (This flag is set in xdisp.c whenever the tool bar is