bug#6154: error from: describe-face font-lock-*

[David Reitter]

X-Debbugs-CC: nathaniel.cunningham@gmail.com

`describe-face' assumes that `find-lisp-object-file-name' always returns a file name.  I'm seeing the bug described below because we're pre-loading font-lock and this function returns `C-source'.

I suggest the patch below. 

Debugger entered--Lisp error: (wrong-type-argument stringp C-source)

  file-name-nondirectory(C-source)

  describe-face((font-lock-constant-face))

  call-interactively(describe-face t nil)

  execute-extended-command(nil)

  call-interactively(execute-extended-command nil nil)

diff --git a/lisp/faces.el b/lisp/faces.el

index 740c7f7..5994f3e 100644

--- a/lisp/faces.el

+++ b/lisp/faces.el

@@ -1406,12 +1406,14 @@ If FRAME is omitted or nil, use the selected frame."

  (setq file-name (find-lisp-object-file-name f 'defface))

  (when file-name

   (princ "Defined in `")

-  (princ (file-name-nondirectory file-name))

+  (princ (if (symbolp file-name) file-name

+   (file-name-nondirectory file-name)))

   (princ "'")

   ;; Make a hyperlink to the library.

-  (save-excursion

-    (re-search-backward "`\\([^`']+\\)'" nil t)

-    (help-xref-button 1 'help-face-def f file-name))

+  (unless (symbolp file-name)

+    (save-excursion

+      (re-search-backward "`\\([^`']+\\)'" nil t)

+      (help-xref-button 1 'help-face-def f file-name)))

   (princ ".")

   (terpri)

   (terpri))

Begin forwarded message:

From: Nathaniel Cunningham <nathaniel.cunningham@gmail.com>

Date: May 10, 2010 1:57:32 AM EDT

To: Development of Aquamacs Emacs <aquamacs-devel@aquamacs.org>

Subject: [Aquamacs-devel] error from: describe-face font-lock-*

Reply-To: Aquamacs Developers <aquamacs-devel@aquamacs.org>

Just came across this error:

M-x describe-face [RET] font-lock-constant-face [RET]

Wrong type argument: stringp, C-source

No *Help* frame appears.  If I then describe a different face sucessfully, e.g. tabbar-default, then repeat the sequence above, the *Help* frame get reused, and says:

Face: font-lock-constant-face (sample) (customize this face)

Documentation:
Font Lock mode face used to highlight constants and labels.

Defined in `

I get the same error for all the font-lock faces tested so far, but no others.