[Emacs-diffs] master d1890a3: New user option 'debugger-stack-frame-as-list'

[Eli Zaretskii]

branch: master
commit d1890a3a4a18f79cabf4caf8d194cdc29ea4bf05
Author: Vasilij Schneidermann <address@hidden>
Commit: Eli Zaretskii <address@hidden>

    New user option 'debugger-stack-frame-as-list'
    
    * src/eval.c (syms_of_eval) <debugger-stack-frame-as-list>: New
    variable.
    * lisp/cus-start.el (standard): Add debugger-stack-frame-as-list.
    * lisp/emacs-lisp/debug.el (debugger-setup-buffer): Adjust
    backtrace processing for the value of debugger-stack-frame-as-list.
    * lisp/emacs-lisp/edebug.el (edebug-backtrace): Adjust backtrace
    processing for the value of debugger-stack-frame-as-list.
    * doc/lispref/debugging.texi (Internals of Debugger): Document
    debugger-stack-frame-as-list.
    * etc/NEWS: Mention 'debugger-stack-frame-as-list'.
---
 doc/lispref/debugging.texi |   31 +++++++++++++++++++++++++++++++
 etc/NEWS                   |    5 +++++
 lisp/cus-start.el          |    1 +
 lisp/emacs-lisp/debug.el   |    4 +++-
 lisp/emacs-lisp/edebug.el  |    4 +++-
 src/eval.c                 |   12 ++++++++++--
 6 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/doc/lispref/debugging.texi b/doc/lispref/debugging.texi
index 2f83b40..710ab92 100644
--- a/doc/lispref/debugging.texi
+++ b/doc/lispref/debugging.texi
@@ -623,6 +623,37 @@ forms are elided.
 @end smallexample
 @end deffn
 
address@hidden debugger-stack-frame-as-list
+If this variable is address@hidden, every stack frame of the backtrace
+is displayed as a list.  This aims at improving the backtrace
+readability at the cost of special forms no longer being visually
+different from regular function calls.
+
+With @code{debugger-stack-frame-as-list} address@hidden, the above
+example would look as follows:
+
address@hidden
address@hidden
+----------- Buffer: backtrace-output ------------
+  (backtrace)
+  (list ...computing arguments...)
address@hidden group
+  (progn ...)
+  (eval (progn (1+ var) (list (quote testing) (backtrace))))
+  (setq ...)
+  (save-excursion ...)
+  (let ...)
+  (with-output-to-temp-buffer ...)
+  (eval (with-output-to-temp-buffer ...))
+  (eval-last-sexp-1 nil)
address@hidden
+  (eval-last-sexp nil)
+  (call-interactively eval-last-sexp)
+----------- Buffer: backtrace-output ------------
address@hidden group
address@hidden smallexample
address@hidden defvar
+
 @defvar debug-on-next-call
 @cindex @code{eval}, and debugging
 @cindex @code{apply}, and debugging
diff --git a/etc/NEWS b/etc/NEWS
index c3f4cf0..dffbac8 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -205,6 +205,11 @@ questions, with a handy way to display help texts.
 +++
 ** 'switch-to-buffer-preserve-window-point' now defaults to t.
 
++++
+** The new variable 'debugger-stack-frame-as-list' allows displaying
+all call stack frames in a Lisp backtrace buffer as lists.  Both
+debug.el and edebug.el have been updated to heed to this variable.
+
 
 * Editing Changes in Emacs 25.3
 
diff --git a/lisp/cus-start.el b/lisp/cus-start.el
index 2b79bbb..d9ad0a5 100644
--- a/lisp/cus-start.el
+++ b/lisp/cus-start.el
@@ -246,6 +246,7 @@ Leaving \"Default\" unchecked is equivalent with specifying 
a default of
             (debug-ignored-errors debug (repeat (choice symbol regexp)))
             (debug-on-quit debug boolean)
             (debug-on-signal debug boolean)
+             (debugger-stack-frame-as-list debugger boolean)
             ;; fileio.c
             (delete-by-moving-to-trash auto-save boolean "23.1")
             (auto-save-visited-file-name auto-save boolean)
diff --git a/lisp/emacs-lisp/debug.el b/lisp/emacs-lisp/debug.el
index 22a3f39..7d27380 100644
--- a/lisp/emacs-lisp/debug.el
+++ b/lisp/emacs-lisp/debug.el
@@ -279,7 +279,9 @@ That buffer should be current already."
   (goto-char (point-min))
   (delete-region (point)
                 (progn
-                  (search-forward "\n  debug(")
+                  (search-forward (if debugger-stack-frame-as-list
+                                       "\n  (debug "
+                                     "\n  debug("))
                   (forward-line (if (eq (car args) 'debug)
                                      ;; Remove debug--implement-debug-on-entry
                                      ;; and the advice's `apply' frame.
diff --git a/lisp/emacs-lisp/edebug.el b/lisp/emacs-lisp/edebug.el
index 1a00c45..6918539 100644
--- a/lisp/emacs-lisp/edebug.el
+++ b/lisp/emacs-lisp/edebug.el
@@ -3798,7 +3798,9 @@ Otherwise call `debug' normally."
          (forward-line 1)
          (delete-region last-ok-point (point)))
 
-        ((looking-at "^  edebug")
+        ((looking-at (if debugger-stack-frame-as-list
+                          "^  (edebug"
+                        "^  edebug"))
          (forward-line 1)
          (delete-region last-ok-point (point))
          )))
diff --git a/src/eval.c b/src/eval.c
index e08a25a..4075610 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -3421,13 +3421,17 @@ Output stream used is value of `standard-output'.  */)
       else
        {
          tem = backtrace_function (pdl);
+         if (debugger_stack_frame_as_list)
+           write_string ("(");
          Fprin1 (tem, Qnil);   /* This can QUIT.  */
-         write_string ("(");
+         if (!debugger_stack_frame_as_list)
+           write_string ("(");
          {
            ptrdiff_t i;
            for (i = 0; i < backtrace_nargs (pdl); i++)
              {
-               if (i) write_string (" ");
+               if (i || debugger_stack_frame_as_list)
+                 write_string(" ");
                Fprin1 (backtrace_args (pdl)[i], Qnil);
              }
          }
@@ -3850,6 +3854,10 @@ This is nil when the debugger is called under 
circumstances where it
 might not be safe to continue.  */);
   debugger_may_continue = 1;
 
+  DEFVAR_BOOL ("debugger-stack-frame-as-list", debugger_stack_frame_as_list,
+              doc: /* Non-nil means display call stack frames as lists. */);
+  debugger_stack_frame_as_list = 0;
+
   DEFVAR_LISP ("debugger", Vdebugger,
               doc: /* Function to call to invoke debugger.
 If due to frame exit, args are `exit' and the value being returned;