Handle case-insensitive filenames for load-path shadows (Bug#5845)

* lisp/emacs-lisp/shadow.el (load-path-shadows-find): Check for
shadowing with case-insensitive matching for files of case-insensitive
directories (as determined by `file-name-case-insensitive-p').
* test/lisp/emacs-lisp/shadow-tests.el: New test.
* test/lisp/emacs-lisp/shadow-resources/p1/foo.el:
* test/lisp/emacs-lisp/shadow-resources/p2/FOO.el: New test files.

1 files changed, 8 insertions, 2 deletions

diff --git a/lisp/emacs-lisp/shadow.el b/lisp/emacs-lisp/shadow.el
index 88a494fdd40..1788f0d71f7 100644
--- a/lisp/emacs-lisp/shadow.el
+++ b/lisp/emacs-lisp/shadow.el
@@ -78,6 +78,7 @@ See the documentation for `list-load-path-shadows' for further information."
         shadows                         ; List of shadowings, to be returned.
         files                           ; File names ever seen, with dirs.
         dir                             ; The dir being currently scanned.
+        dir-case-insensitive            ; `file-name-case-insentive-p' for dir.
         curr-files                      ; This dir's Emacs Lisp files.
         orig-dir                        ; Where the file was first seen.
         files-seen-this-dir             ; Files seen so far in this dir.
@@ -104,6 +105,9 @@ See the documentation for `list-load-path-shadows' for further information."
              (message "Checking %d files in %s..." (length curr-files) dir))
 
         (setq files-seen-this-dir nil)
+        ;; We assume that case sensitivity of a directory applies to
+        ;; its files.
+        (setq dir-case-insensitive (file-name-case-insensitive-p dir))
 
         (dolist (file curr-files)
 
@@ -123,10 +127,12 @@ See the documentation for `list-load-path-shadows' for further information."
             ;; XXX.elc (or vice-versa) when they are in the same directory.
             (setq files-seen-this-dir (cons file files-seen-this-dir))
 
-            (if (setq orig-dir (assoc file files))
+            (if (setq orig-dir (assoc file files
+                                      (when dir-case-insensitive
+                                        (lambda (f1 f2) (eq (compare-strings f1 nil nil f2 nil nil t) t)))))
                 ;; This file was seen before, we have a shadowing.
                 ;; Report it unless the files are identical.
-                (let ((base1 (concat (cdr orig-dir) "/" file))
+                (let ((base1 (concat (cdr orig-dir) "/" (car orig-dir)))
                       (base2 (concat dir "/" file)))
                   (if (not (and load-path-shadows-compare-text
                                 (load-path-shadows-same-file-or-nonexistent