bug#27986: 26.0.50; 'rename-file' can rename files without confirmation

[Paul Eggert <eggert@cs.ucla.edu>]

On 09/11/2017 07:47 AM, Eli Zaretskii wrote:
> do these changes modify interactive
> behavior in incompatible ways?  I thought we agreed to leave the
> interactive behavior intact, and only change the non-interactive uses.
>
That wasn't my understanding. In our last email exchange about 
interactivity I proposed that Emacs prompt the user when the destination 
is not a directory name but happens to be a directory (see 
Bug#27986#97), but you were dubious about that (Bug#27986#100) so I left 
it alone.

I normally use dired to rename files in Emacs, and dired's behavior 
hasn't changed as far as I can tell. Where there is a bit of a change is 
when using M-x rename-file directly. Here, in the typical case with file 
name completion there is still no difference, since names of destination 
directories are completed to have trailing /. However, if one uses "M-x 
rename-file foo RET and then laboriously types out the name of an 
existing directory /tmp/destination-dir without using completion and 
without trailing / before hitting RET, one will notice a difference: 
rename-file will now say "File /tmp/destination-dir already exists; 
rename to it anyway? (yes or no)" and if one types "yes" the rename will 
typically fail. So yes, this is a (noisy) incompatibility with previous 
usage. If you like I can go back and implement the suggestion in 
Bug#27986#97; this would be more-compatible with existing usage. I 
suggest leaving it alone, though, as things are simpler and easier to 
explain the way they are.