bug#28513: 25.1; ido insists on guessing the wrong directory

[Dmitry Gutov <dgutov@yandex.ru>]

On 14.12.2020 18:42, Lars Ingebrigtsen wrote:

>> Okay, but why does the fallback command end up trying to overwrite the
>> original file, even though, in your scenario, input ends with /vc/?
> 
> In essence, it's doing this (if we say we've navigated to "/tmp/" before
> `C-f'):
> 
> (let ((default-directory "/tmp/"))
>    (call-interactively 'write-file))
> 
> This gives you a prompt of
> 
> Write file: /tmp/
> 
> If you then hit RET, then:
> 
> 
> 
> That is, hitting RET in the `write-file' dialogue gives you
> buffer-file-name, and ignores whatever is in the prompt.  This seems
> contrary to what the doc string says:
> 
> ---
> Interactively, prompt for FILENAME.
> If you specify just a directory name as FILENAME, that means to write
> to a file in that directory.  In this case, the base name of the file
> is the same as that of the file visited in the buffer, or the buffer
> name sans leading directories, if any, if the buffer is not already
> visiting a file.
> ---
> 
> So this isn't an ido problem at all -- it's a bug in `write-file'?  Or
> rather...
> 
> (let ((default-directory "/tmp/")) (read-file-name "Foo: "))
> 
> If you just hit RET there, it'll return `buffer-file-name'.

But there is a difference between having default-directory set to /tmp/ 
and typing /tmp/ yourself.

I think when the user calls the escape hatch command, they don't expect 
their current input to translate to the new default-directory value. 
Rather, it should be the input in the new prompt.

Might not be easy to fix, however, given that the current code in Ido 
tries to do that in the most generic way:

         (let ((default-directory ido-current-directory)
	      (read-file-name-function nil))
	  (setq this-command (or ido-fallback fallback 'find-file))
	  ...
	  (call-interactively this-command))

And since that this feature is an escape hatch and, say, fido-mode 
(which everyone will migrate to any year now) shouldn't need anything 
like it, maybe it's not worth the effort fixing.