Making filenames/line numbers linkable in Emacs gud buffer

Question

I'm running pdb on my testcases in Python through the gud buffer. When I get a stacktrace/failure in my testcase, it looks like this:

FAIL: test_foo_function (__main__.TestFoo)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test/testfoo.py", line 499, in test_foo_function
    self.assertEqual('foo', 'foo')

I'd love to be able to make the line(s) like:

File "test/testfoo.py", line 499, in test_foo_function

clickable and take be to line 499 in testfoo.py.

(edit) The folks on the python-mode list led me to pdbtrack and I was able to get it to work there. See answer below...

Answer 1

Thanks to a hint by Gerard B I figured it out. I'm doing this from pdbtrack (shell) instead of pure pdb, but it should work in both I believe. You need to enable compilation-shell-minor-mode. And have the following code in your .emacs:

;; if compilation-shell-minor-mode is on, then these regexes
;; will make errors linkable
(defun matt-add-global-compilation-errors (list)
  (dolist (x list)
    (add-to-list 'compilation-error-regexp-alist (car x))
    (setq compilation-error-regexp-alist-alist
      (cons x
            (assq-delete-all (car x)
                             compilation-error-regexp-alist-alist)))))

(matt-add-global-compilation-errors
 `(
   (matt-python ,(concat "^ *File \\(\"?\\)\\([^,\" \n    <>]+\\)\\1"
                    ", lines? \\([0-9]+\\)-?\\([0-9]+\\)?")
           2 (3 . 4) nil 2 2)
   (matt-pdb-stack ,(concat "^>?[[:space:]]*\\(\\([-_./a-zA-Z0-9 ]+\\)"
                       "(\\([0-9]+\\))\\)"
                       "[_a-zA-Z0-9]+()[[:space:]]*->")
              2 3 nil 0 1)
   (matt-python-unittest-err "^  File \"\\([-_./a-zA-Z0-9 ]+\\)\", line \\([0-9]+\\).*" 1 2)
   )
 )

(defun matt-set-local-compilation-errors (errors)
  "Set the buffer local compilation errors.

Ensures than any symbols given are defined in
compilation-error-regexp-alist-alist."
  (dolist (e errors)
     (when (symbolp e)
      (unless (assoc e compilation-error-regexp-alist-alist)
        (error (concat "Error %s is not listed in "
                       "compilation-error-regexp-alist-alist")
               e))))
  (set (make-local-variable 'compilation-error-regexp-alist)
       errors))

Then you can use standard compile mode navigation to zip through the error stack trace.

Answer 2

I think what you want to customize is compilation-parse-errors-filename-function, which is a function that takes a filename, and returns a modified version of the filename to be displayed. This is a buffer local variable, so you should set it in each buffer that will be displaying python errors (there is probably an appropriate hook to use, I do not have python mode installed so I cannot look it up). You would use propertize to return a version of the input filename that acts as a hyperlink to load the actual file. propertize is well documented in the elisp manual.

If compilation-parse-errors-filename-function is not getting called, then you want to add a list to compilation-error-regexp-alist-alist (that does say alist-alist, that is not a typo) which is a list of mode names followed by regular expressions to match errors, and numerical indexes of the matching line number, filename etc. info in the error regexp match.