bug#5845: load-library vs. list-load-path-shadows

[Noam Postavsky <npostavs@users.sourceforge.net>]

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On Tue, Jan 16, 2018 at 12:25 PM, Ken Brown <kbrown@cornell.edu> wrote:
> On 1/16/2018 10:54 AM, Noam Postavsky wrote:
>>
>> Should we just use case-insensitive compare for `windows-nt' systems?
>> The idea of using "the same heuristics" as `load' sounds nice, but as
>> far as I can tell, `load' just queries the file system directly. Doing
>> the same in `load-path-shadow-find' is far too slow (raises execution
>> time from 0.38s to 5.64s, and that's without any packages adding to
>> the load-path).
>
>
> Would it help to use file-name-case-insensitive-p?

Ah, good point. How about the attached?

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From acbdb32b0a1973ad3f9c361748d9aa3c461e2449 Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Tue, 16 Jan 2018 16:26:56 -0500
Subject: [PATCH v2] 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-insentive-p').
---
 lisp/emacs-lisp/shadow.el | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/lisp/emacs-lisp/shadow.el b/lisp/emacs-lisp/shadow.el
index 88a494f..6402695 100644
--- a/lisp/emacs-lisp/shadow.el
+++ b/lisp/emacs-lisp/shadow.el
@@ -78,6 +78,7 @@ load-path-shadows-find
 	shadows				; List of shadowings, to be returned.
 	files				; File names ever seen, with dirs.
 	dir				; The dir being currently scanned.
+	dir-case-sensitive              ; `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 @@ load-path-shadows-find
 	     (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-sensitive (file-name-case-sensitive-p dir))
 
 	(dolist (file curr-files)
 
@@ -123,7 +127,9 @@ load-path-shadows-find
 	    ;; 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
+                                      (unless dir-case-sensitive
+                                        (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))
-- 
2.6.2.windows.1