bug#50387: closed (Possible bug in Tramp or in completions)

[GNU bug Tracking System]

Your message dated Tue, 07 Sep 2021 17:51:17 +0000
with message-id <11c4e3821a7883ef488a@heytings.org>
and subject line Re: bug#50387: Possible bug in Tramp or in completions
has caused the debbugs.gnu.org bug report #50387,
regarding Possible bug in Tramp or in completions
to be marked as done.

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50387: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=50387
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> --- Begin Message ---
>
>
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> Subject: 
>
> Possible bug in Tramp or in completions
>
>
>
>
> Date: 
>
> Sun, 05 Sep 2021 00:43:59 +0000
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>
>
>
>
> With a ~/.ssh/config file containing two entries:
>
> Host foo
>   ...
> Host bar
>   ...
>
> emacs -Q
> M-: (setq tramp-default-method "ssh")
> M-: (add-to-list 'completion-styles 'substring)
> C-x C-x /ssh: TAB
>
> displays "Sole completion".  If, instead of having completion-styles set 
> to:
>
> (substring basic partial-completion emacs22)
>
> it is set to:
>
> (basic substring partial-completion emacs22)
>
> then two completion candidates are shown (as expected): "ssh:foo:" and 
> "ssh:bar:".
>
> This happens because the "substring" completion mechanism is tried first 
> by completion--some in completion--nth-completion, and returns (t . 
> substring), because
>
> (completion-substring-try-completion "/ssh:" #'completion-file-name-table 
> #'file-exists-p 5)
>
> returns t, because
>
> (completion-substring--all-completions "/ssh:" 
> #'completion-file-name-table #'file-exists-p 5) returns (("ssh:")
>
> returns (prefix "ssh:") "/" "" 1), because
>
> (completion-boundaries "/ssh:" #'completion-file-name-table 
> #'file-exists-p "")
>
> returns (1 . 0).
>
> When the "basic" completion mechanism is tried first,
>
> (completion-basic-try-completion "/ssh:" #'completion-file-name-table 
> #'file-exists-p 5)
>
> returns ("/ssh:" . 5).
>
> It is not clear to me whether this is a bug (I always thought that the 
> order of completion mechanisms in completion-styles did not matter, and in 
> this case it does indeed make no difference with (setq 
> tramp-default-method "scp")), and if so if it is a bug in Tramp, or in the 
> completion functions.
>
>
>
> --- End Message ---
> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#50387: Possible bug in Tramp or in completions
>
>
>
>
> Date: 
>
> Tue, 07 Sep 2021 17:51:17 +0000
>
>
>
>
>
> > > > That means, "scp:" hasn't been passed to 
> > > > tramp-completion-handle-file-name-all-completions, and the result of 
> > > > that function looks proper to me.
> > >
> > > Yet it isn't.
> >
> > Why not? In this example, `completion-styles' contains `substring'. And 
> > then you ask for completion of "/scp:". Looking at the candidates 
> > returned by `tramp-completion-handle-file-name-all-completions', only 
> > "pscp:" and "scp:" have the substring "scp:".
>
> Because after typing "/s" or "/sc" or "/scp" it makes sense to see that 
> "/scp:" is among the completion candidates, but after typing "/scp:" it 
> doesn't make sense anymore, the method has already been entered by the 
> user, what they now want to see is a list of hosts, and there is no way to 
> see it.
>
> > > - before your attempt to fix the problem, C-x C-f / TAB only displayed 
> > > "scp:" and "scpx:" among the completion candidates (or e.g. "ssh:", 
> > > "sshfs:" and "sshx:" with tramp-default-method set to "ssh");
> >
> > Yes, this is changed.
> >
> > > - now C-x C-f / TAB displays all Tramp methods;
> >
> > When Tramp is loaded. I regard this to be correct.
> >
> > > - with my patch, which actually fixes the bug, C-x C-f / TAB does not 
> > > display any Tramp method, as it should.
> >
> > Again, C-x C-f / TAB displays a Tramp method only when Tramp is loaded.
>
> I filed a bug report, explained in every detail what the bug is, provided 
> a patch, and the end result is a situation that is worse than earlier.  I 
> expect other bug reports from confused users, and hope that you'll change 
> your mind.
>
> Closing.
>
>
> --- End Message ---