1 ;;; shadow.el --- Locate Emacs Lisp file shadowings.
3 ;; Copyright (C) 1995 Free Software Foundation, Inc.
5 ;; Author: Terry Jones <terry@santafe.edu>
7 ;; Created: 15 December 1995
9 ;; This file is part of XEmacs.
11 ;; XEmacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 2, or (at your option)
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
24 ;; Boston, MA 02111-1307, USA.
28 ;; The functions in this file detect (`find-emacs-lisp-shadows')
29 ;; and display (`list-load-path-shadows') potential load-path
30 ;; problems that arise when Emacs Lisp files "shadow" each other.
32 ;; For example, a file XXX.el early in one's load-path will shadow
33 ;; a file with the same name in a later load-path directory. When
34 ;; this is unintentional, it may result in problems that could have
35 ;; been easily avoided. This occurs often (to me) when installing a
36 ;; new version of emacs and something in the site-lisp directory
37 ;; has been updated and added to the emacs distribution. The old
38 ;; version, now outdated, shadows the new one. This is obviously
41 ;; The `list-load-path-shadows' function was run when you installed
42 ;; this version of emacs. To run it by hand in emacs:
44 ;; M-x load-library RET shadow RET
45 ;; M-x list-load-path-shadows
47 ;; or run it non-interactively via:
49 ;; emacs -batch -l shadow.el -f list-load-path-shadows
51 ;; Thanks to Francesco Potorti` <pot@cnuce.cnr.it> for suggestions,
52 ;; rewritings & speedups.
54 ;; 1998-08-15 Martin Buchholz: Speed up using hash tables instead of lists.
58 (defun find-emacs-lisp-shadows (&optional path)
59 "Return a list of Emacs Lisp files that create shadows.
60 This function does the work for `list-load-path-shadows'.
62 We traverse PATH looking for shadows, and return a \(possibly empty\)
63 even-length list of files. A file in this list at position 2i shadows
64 the file in position 2i+1. Emacs Lisp file suffixes \(.el and .elc\)
65 are stripped from the file names in the list.
67 See the documentation for `list-load-path-shadows' for further information."
69 (let (shadows ; List of shadowings, to be returned.
70 dir ; The dir being currently scanned.
71 curr-files ; This dir's Emacs Lisp files.
72 orig-dir ; Where the file was first seen.
73 (file-dirs ; File names ever seen, with dirs.
74 (make-hash-table :size 2000 :test 'equal))
75 (true-names ; Dirs ever considered.
76 (make-hash-table :size 50 :test 'equal))
77 (files-seen-this-dir ; Files seen so far in this dir.
78 (make-hash-table :size 100 :test 'equal))
81 (dolist (path-elt (or path load-path))
83 (setq dir (file-truename (or path-elt ".")))
84 (if (gethash dir true-names)
85 ;; We have already considered this PATH redundant directory.
86 ;; Show the redundancy if we are interactive, unless the PATH
87 ;; dir is nil or "." (these redundant directories are just a
88 ;; result of the current working directory, and are therefore
89 ;; not always redundant).
92 (not (string= path-elt "."))
93 (message "Ignoring redundant directory %s" path-elt)))
95 (puthash dir t true-names)
96 (setq dir (or path-elt "."))
97 (setq curr-files (if (file-accessible-directory-p dir)
98 (directory-files dir nil ".\\.elc?$" t)))
101 (message "Checking %d files in %s..." (length curr-files) dir))
103 (clrhash files-seen-this-dir)
105 (dolist (file curr-files)
107 (setq file (substring
108 file 0 (if (string= (substring file -1) "c") -4 -3)))
110 ;; FILE now contains the current file name, with no suffix.
111 (unless (or (gethash file files-seen-this-dir)
112 ;; Ignore these files.
121 ;; File has not been seen yet in this directory.
122 ;; This test prevents us declaring that XXX.el shadows
123 ;; XXX.elc (or vice-versa) when they are in the same directory.
124 (puthash file t files-seen-this-dir)
126 (if (setq orig-dir (gethash file file-dirs))
127 ;; This file was seen before, we have a shadowing.
130 (list (concat (file-name-as-directory orig-dir)
132 (concat (file-name-as-directory dir)
135 ;; Not seen before, add it to the list of seen files.
136 (puthash file dir file-dirs))))))
138 ;; Return the list of shadowings.
143 (defun list-load-path-shadows ()
144 "Display a list of Emacs Lisp files that shadow other files.
146 This function lists potential load-path problems. Directories in the
147 `load-path' variable are searched, in order, for Emacs Lisp
148 files. When a previously encountered file name is found again, a
149 message is displayed indicating that the later file is \"hidden\" by
152 For example, suppose `load-path' is set to
154 \(\"/usr/gnu/emacs/site-lisp\" \"/usr/gnu/emacs/share/emacs/19.30/lisp\"\)
156 and that each of these directories contains a file called XXX.el. Then
157 XXX.el in the site-lisp directory is referred to by all of:
158 \(require 'XXX\), \(autoload .... \"XXX\"\), \(load-library \"XXX\"\) etc.
160 The first XXX.el file prevents emacs from seeing the second \(unless
161 the second is loaded explicitly via load-file\).
163 When not intended, such shadowings can be the source of subtle
164 problems. For example, the above situation may have arisen because the
165 XXX package was not distributed with versions of emacs prior to
166 19.30. An emacs maintainer downloaded XXX from elsewhere and installed
167 it. Later, XXX was updated and included in the emacs distribution.
168 Unless the emacs maintainer checks for this, the new version of XXX
169 will be hidden behind the old \(which may no longer work with the new
172 This function performs these checks and flags all possible
173 shadowings. Because a .el file may exist without a corresponding .elc
174 \(or vice-versa\), these suffixes are essentially ignored. A file
175 XXX.elc in an early directory \(that does not contain XXX.el\) is
176 considered to shadow a later file XXX.el, and vice-versa.
178 When run interactively, the shadowings \(if any\) are displayed in a
179 buffer called `*Shadows*'. Shadowings are located by calling the
180 \(non-interactive\) companion function, `find-emacs-lisp-shadows'."
183 (let* ((path (copy-sequence load-path))
186 ;; If we can find simple.el in two places,
188 (if (file-exists-p (expand-file-name "simple.el" (car tem)))
189 (setq toplevs (cons (car tem) toplevs)))
190 (setq tem (cdr tem)))
191 (if (> (length toplevs) 1)
192 ;; Cut off our copy of load-path right before
193 ;; the second directory which has simple.el in it.
194 ;; This avoids loads of duplications between the source dir
195 ;; and the dir where these files were copied by installation.
196 (let ((break (nth (- (length toplevs) 2) toplevs)))
199 (if (eq (nth 1 tem) break)
203 (setq tem (cdr tem)))))
205 (let* ((shadows (find-emacs-lisp-shadows path))
206 (n (/ (length shadows) 2))
207 (msg (format "%s Emacs Lisp load-path shadowing%s found"
208 (if (zerop n) "No" (concat "\n" (number-to-string n)))
209 (if (= n 1) " was" "s were"))))
212 ;; We are interactive.
213 ;; Create the *Shadows* buffer and display shadowings there.
214 (let ((output-buffer (get-buffer-create "*Shadows*")))
215 (display-buffer output-buffer)
216 (set-buffer output-buffer)
219 (insert (format "%s hides %s\n" (car shadows)
220 (car (cdr shadows))))
221 (setq shadows (cdr (cdr shadows))))
223 ;; We are non-interactive, print shadows via message.
225 (message "This site has duplicate Lisp libraries with the same name.
226 If a locally-installed Lisp library overrides a library in the Emacs release,
227 that can cause trouble, and you should probably remove the locally-installed
228 version unless you know what you are doing.\n")
230 (message "%s hides %s" (car shadows) (car (cdr shadows)))
231 (setq shadows (cdr (cdr shadows))))
232 (message "%s" msg))))))
236 ;;; shadow.el ends here