bug#49776: 28.0.50; Incorrect username completion results reported by `read-file-name-interal`

[Daniel Mendler <mail@daniel-mendler.de>]

On 7/30/21 1:47 PM, Lars Ingebrigtsen wrote:
>> `(all-completions "~/.config/~man" #'read-file-name-internal)` returns
>> the list `("/.config/~man")`. The file completion table incorrectly
>> recognizes "/.config/~man" as the username instead of only "~man".
> 
> I'm unable to reproduce this problem, and you haven't used `M-x
> report-emacs-bug', so I don't know what system you're seeing this on.
> I'm getting the expected on Debian/bullseye:
> 
> (all-completions "~/.config/~man" #'read-file-name-internal)
> => (#("/.config/~man/" 0 13 (face completions-common-part)))

No, this is exactly the problem I meant (You reproduced it).
"/.config/~man" is an invalid completion string. It is not a valid path
nor a valid username on my system. The file completion table should not
return invalid completion candidates.

> And, of course:
> 
> (all-completions "~/.config/~man/" #'read-file-name-internal)
> => ("tr/" "zh/" "CACHEDIR.TAG" "de/" "ru/" "ro/" "cat3/" "it/" "pt/" "./" "cat7/" "zh_TW/" "sr/" "fr.ISO8859-1/" "hr/" "cat6/" "fi/" "ja/" "index.db" "cat1/" "cat2/" "cat5/" "cat8/" "vi/" "ko/" "nl/" "uk/" "sl/" "../" "zh_CN/" "id/" "hu/" "da/" "sv/" "es/" "fr.UTF-8/" "pt_BR/" "cs/" "pl/" "sk/" "cat4/" "fr/")

Yes, of course. This works correctly and as expected.

Daniel