bug#25393: FEATURE REQUEST: *Backtrace* -- C source code def highlight + jump to def.
As a feature request, the Emacs team may wish to consider implementing the ability for users to highlight C source code definitions in the *Backtrace* buffer and jump to the function definitions. The highlighting of said functions makes the *Backtrace* buffer prettier, and it's handy to jump to the definitions with buttons. A check should probably be included to see whether the `find-function-C-source-directory' contains C source code files before creating highlighting/buttons for jumping:
In my use-case, it wasn't very obvious to me that `/` was the cause of my backtrace error message because it was not highlighted -- this is true even though I am aware that the problem is always near the top of the debugger buffer. It is just not a function I use a lot and it didn't really look like a function because it was just regular text coloration.
(defun debugger-make-xrefs (&optional buffer)
"Attach cross-references to function names in the `*Backtrace*' buffer."
(with-current-buffer (or buffer (current-buffer))
(setq buffer (current-buffer))
(let ((inhibit-read-only t)
(old-end (point-min)) (new-end (point-min)))
(let (old-start new-start (all-match t))
(while (and all-match (not (bobp)))
(setq old-end (point))
(setq old-start (point))
(setq new-end (point))
(setq new-start (point)))
(if (not (zerop
(let ((case-fold-search nil))
(current-buffer) old-start old-end
buffer new-start new-end))))
(setq all-match nil))))
(delete-region new-end (point-max))
(insert (substring debugger-previous-backtrace
(- old-end (point-min))))
(narrow-to-region (point-min) new-end)))
(goto-char (+ (point) 2))
(let* ((beg (point))
(end (progn (skip-syntax-forward "w_") (point)))
(fn (function-called-at-point)) ;; MODIFICATION
(sym (intern-soft (buffer-substring-no-properties beg end)))
(advised (and (symbolp function)
(advice--p (advice--symbol-function function))))
;; If the function is advised, use the symbol that has the
;; real definition, if that symbol is already set up.
(or (and advised
(advice--cd*r (advice--symbol-function function)))
;; Get the real definition.
(def (if (symbolp real-function)
(or (symbol-function real-function)
(signal 'void-function (list real-function)))
(aliased (or (symbolp def)
;; Advised & aliased function.
(and advised (symbolp real-function)
(not (eq 'autoload (car-safe def))))))
(file-name (find-lisp-object-file-name function (if aliased 'defun
(and sym (symbol-file sym 'defun)))))
(when (or fn file) ;; MODIFICATION
(help-xref-button 0 'help-function-def sym file)))
(setq debugger-previous-backtrace (buffer-string)))))
> A check should probably be included to see whether the
> `find-function-C-source-directory' contains C source code files before
> creating highlighting/buttons for jumping:
I chose not to do this. I think it's better to make the buttons
and give an error message when they are pressed if
'find-function-C-source-directory' is misconfigured, because then the
error message lets the user know that there is a configuration problem
so that she or he can try to fix it.
Let me know if you are able to give this a try and how it works for you.