(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, 18 insertions, 2 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 2a979c5cb9e..aa1d4433914 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -3072,10 +3072,24 @@ dsafe__call (bool inhibit_quit, Lisp_Object (f) (ptrdiff_t, Lisp_Object *),
   return val;
 }
 
+static Lisp_Object
+funcall_with_backtraces (ptrdiff_t nargs, Lisp_Object *args)
+{
+  /* If an error is signaled during a Lisp hook in redisplay, write a
+     backtrace into the buffer *Redisplay-trace*.  */
+  push_handler_bind (list_of_error, Qdebug_early__muted, 0);
+  Lisp_Object res = Ffuncall (nargs, args);
+  pop_handler ();
+  return res;
+}
+
 #define SAFE_CALLMANY(inhibit_quit, f, array) \
   dsafe__call ((inhibit_quit), f, ARRAYELTS (array), array)
-#define dsafe_calln(inhibit_quit, ...) \
-  SAFE_CALLMANY ((inhibit_quit), Ffuncall, ((Lisp_Object []) {__VA_ARGS__}))
+#define dsafe_calln(inhibit_quit, ...)                 \
+  SAFE_CALLMANY ((inhibit_quit),                       \
+                 backtrace_on_redisplay_error          \
+                 ? funcall_with_backtraces : Ffuncall, \
+                 ((Lisp_Object []) {__VA_ARGS__}))
 
 static Lisp_Object
 dsafe_call1 (Lisp_Object f, Lisp_Object arg)
@@ -37748,6 +37762,8 @@ cursor shapes.  */);
   DEFSYM (Qthin_space, "thin-space");
   DEFSYM (Qzero_width, "zero-width");
 
+  DEFSYM (Qdebug_early__muted, "debug-early--muted");
+
   DEFVAR_LISP ("pre-redisplay-function", Vpre_redisplay_function,
                doc: /* Function run just before redisplay.
 It is called with one argument, which is the set of windows that are to