bug#59674: 28.2; icomplete-force-complete Incorrectly Completes Filename Case

bug#59674: 28.2; icomplete-force-complete Incorrectly Completes Filename Case

[Cameron Norton]

Using icomplete, I often navigate to certain files by using a single
character for each component of the path name before completing with
icomplete-force-complete, which I have bound to <tab> while in the
minibuffer. So a file

./foo/bar/baz/asdf.txt

would be visited via the sequence

C-x C-f f/b/b/a <tab> <return>

Using icomplete-force-complete this way emulates the <tab> behavior in
completion packages like Vertico without the extra dependency.

However, with completion case sensitivity disabled, this sometimes
results in the file's path being completed incorrectly with regards to
capitalization. This is very noticeable when finding files in the usual
subdirectories of $HOME, with ~/doc <tab> completing to ~/documents/
rather than ~/Documents/, for example.

I can consistently reproduce this behavior through these steps. I have
done this on both my usual Emacs 28.2 as well as the git master
(currently 7939184).

 1. Start a clean emacs via emacs -Q.

 2. Evaluate the following:
      (icomplete-mode)
      (setq read-file-name-completion-ignore-case t)

 3. Navigate to some subdirectory of $HOME via M-x cd or equivalent.

 4. Start using C-x C-f to find a file in a different subdirectory of
    $HOME. The target file should be located in a subdirectory that
    starts with a capital letter (e.g. start finding something under
    ~/Documents somewhere).

 5. Enter the file's pathname relative to the home directory (starting
    with ~/) or an abbreviation like above using all lowercase
    letters. Do not use any completion while doing so, and do not clear
    the minibuffer of the current non-home directory beforehand.

 6. Complete the whole filename using icomplete-force-complete, which is
    bound to C-M-i by default.

An example run on my machine has me cd to ~/Downloads

M-x cd <return> ~/Downloads <return>

then try to find the file ~/Documents/Misc/asdf.org by entering

C-x C-f ~/d/m/a C-M-i

This instead completes to ~/documents/Misc/asdf.org, with "Documents"
uncapitalized but the other components completing with proper
capitalization.

(Apologies if this sent twice, I'm having unrelated technical issues.)

Cameron Norton

---

In GNU Emacs 28.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.34, cairo version 1.17.6)
 of 2022-09-12 built on frederik
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Arch Linux

Configured using:
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bug#59674: 28.2; icomplete-force-complete Incorrectly Completes Filename Case

[Eli Zaretskii]

> From: Cameron Norton <cameron.norton@gmail.com>
> Date: Mon, 28 Nov 2022 19:55:06 -0800
> 
> 
> Using icomplete, I often navigate to certain files by using a single
> character for each component of the path name before completing with
> icomplete-force-complete, which I have bound to <tab> while in the
> minibuffer. So a file
> 
> ./foo/bar/baz/asdf.txt
> 
> would be visited via the sequence
> 
> C-x C-f f/b/b/a <tab> <return>
> 
> Using icomplete-force-complete this way emulates the <tab> behavior in
> completion packages like Vertico without the extra dependency.
> 
> However, with completion case sensitivity disabled, this sometimes
> results in the file's path being completed incorrectly with regards to
> capitalization. This is very noticeable when finding files in the usual
> subdirectories of $HOME, with ~/doc <tab> completing to ~/documents/
> rather than ~/Documents/, for example.

I cannot reproduce what you describe.  I see a completely different
behavior: as soon as I type ~/d/m M-C-i, ~/Documents disappears from the
completions, and I see only ~/dir/moo ("dir" is another directory I have
under my home directory).

So I'm not sure why you see what you see: perhaps there's some step missing
in the recipe?

bug#59674: 28.2; icomplete-force-complete Incorrectly Completes Filename Case

[Gregory Heytings]

>
> I cannot reproduce what you describe.  I see a completely different 
> behavior: as soon as I type ~/d/m M-C-i, ~/Documents disappears from the 
> completions, and I see only ~/dir/moo ("dir" is another directory I have 
> under my home directory).
>
> So I'm not sure why you see what you see: perhaps there's some step 
> missing in the recipe?
>

The recipe is not incomplete, but it must be followed very carefully (it's 
really a corner case):

mkdir -p ~/Zack/foo/bar ~/zock
echo baz > ~/Zack/foo/bar/baz.txt
emacs -Q
M-x icomplete-mode RET
M-: (setq read-file-name-completion-ignore-case t) RET
M-x cd ~/zock RET
C-x C-f ~/z/f/b/b ;; only type these characters, with only lower case letters
;; at that point you should see this in the minibuffer:
;; Find file: ~/zock/~/z/f/b/b[...ack/foo/bar/baz.txt] [Matched]
C-M-i
;; now you see:
;; Find file: ~/zock/~/zack/foo/bar/baz.txt[...ack/foo/bar/baz.txt] [Matched]
RET
;; the above baz.txt file is not opened, instead a new empty file is created, and you see:
;; Use M-x make-directory RET RET to create the directory and its parent