[PATCH] copy: distinguish "file exists" cases and add a hint (BC)

[Augie Fackler]

> On Sep 27, 2016, at 11:23, Pierre-Yves David <pierre-yves.david at ens-lyon.org> wrote:
> On 09/26/2016 10:36 PM, Augie Fackler wrote:
>> # HG changeset patch
>> # User Augie Fackler <augie at google.com>
>> # Date 1474319739 14400
>> #      Mon Sep 19 17:15:39 2016 -0400
>> # Node ID a1b65d0019f9ce96961c5c9533a8658a92e5b9d4
>> # Parent  129e38a76f2ca43291ed3a12d92b5d4b7e3b7f2b
>> copy: distinguish "file exists" cases and add a hint (BC)
> 

I'll get a v4 rolled tonight yet, assuming it doesn't turn out twisty and confusing to thread the action down into cmdutil.

>> Users that want to add a copy record to an existing commit with 'hg
>> commit --amend' should be guided towards this workflow, rather than
>> reaching for some sort of uncommit-recommit flow. As part of this,
>> distinguish in the top-line error message whether the file merely
>> already exists (untracked) on disk or the file already exists in
>> history.
> 
> Small side not. being able to record the copy after the fact is great and that is great that this changesets work toward making it more discoverable. Another important point would be to allow the same thing for move.
> 
>> diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
>> --- a/mercurial/cmdutil.py
>> +++ b/mercurial/cmdutil.py
>> @@ -640,8 +640,15 @@ def copy(ui, repo, pats, opts, rename=Fa
>> 
>>         if not after and exists or after and state in 'mn':
>>             if not opts['force']:
>> -                ui.warn(_('%s: not overwriting - file exists\n') %
>> -                        reltarget)
>> +                if state in 'mn':
>> +                    msg = _('%s: not overwriting - file already committed\n')
>> +                    hint = _('(hg copy --after --force to replace the '
>> +                             'file by recording a copy)\n')
> 
> This "replace" here is confusing. --after seems to point out that no actual replacement occurs, just a 'recording'. Why does this message mention 'replace' in addition to 'record'.

Folks on irc were very insistent that the word replace matters, notably timeless. My algorithm is that timeless is right about these things pretty much by default, so I went with a tweak of his wording. I'm not going to change this in the next version unless I hear a lot about it from native speakers.

(I agree the word replace here is a little odd, but it's not strictly wrong data-model wise, and the hint text is very much something we can tweak if it's a problem in the real world.)

> 
>> +                else:
>> +                    msg = _('%s: not overwriting - file exists\n')
>> +                    hint = _('(hg copy --after to record the copy)\n')
>> +                ui.warn(msg % reltarget)
>> +                ui.warn(hint)
>>                 return
>> 
>>         if after:
>> diff --git a/tests/test-copy.t b/tests/test-copy.t
>> --- a/tests/test-copy.t
>> +++ b/tests/test-copy.t
>> @@ -226,11 +226,23 @@ foo was clean:
>>   C foo
>> Trying to copy on top of an existing file fails,
>>   $ hg copy -A bar foo
>> -  foo: not overwriting - file exists
>> +  foo: not overwriting - file already committed
>> +  (hg copy --after --force to replace the file by recording a copy)
>> +same error without the --after, so the user doesn't have to go through
>> +two hints:
>> +  $ hg copy bar foo
>> +  foo: not overwriting - file already committed
>> +  (hg copy --after --force to replace the file by recording a copy)
> 
> I'm not sure why pointing to --after here is correct? If the user did not used '--after' in the first place it is likely that they want to actually replace the destination content with the source content. Isn't it?

Aw, heck. There are actually 6 cases:

+-------------+------------+--------------+
|             |            |              |
|             | replace    |preserve      |
|             | dest.      |dest.         |
|             | contents   |contents      |
|             |            |              |
+-------------+------------+--------------+
|             |            |              |
| dest        |            |  --after     |
| doesn't     | [no flags] | [an error]   |
| exist       |            |              |
+-------------+------------+--------------+
|             |            |              |
| dest. exists|            |              |
| but is not  | --force    | --after      |
| tracked     |            |              |
|             |            |              |
+-------------+------------+--------------+
|             |            |              |
| dest exists |            |              |
| and is      | --force    | --after      |
| tracked     |            | --force      |
|             |            |              |
+-------------+------------+--------------+


> 
>> but it's considered modified after a copy --after --force
>>   $ hg copy -Af bar foo
>>   $ hg st -AC foo
>>   M foo
>>     bar
>> +The hint for a file that exists but is not in file history doesn't
>> +mention --force:
>> +  $ touch xyzzy
>> +  $ hg cp bar xyzzy
>> +  xyzzy: not overwriting - file exists
>> +  (hg copy --after to record the copy)
>> 
>>   $ cd ..
>> diff --git a/tests/test-rename.t b/tests/test-rename.t
>> --- a/tests/test-rename.t
>> +++ b/tests/test-rename.t
>> @@ -265,7 +265,8 @@ move everything under directory d1 to ex
>> overwrite existing files (d2/b)
>> 
>>   $ hg rename d1/* d2
>> -  d2/b: not overwriting - file exists
>> +  d2/b: not overwriting - file already committed
>> +  (hg copy --after --force to replace the file by recording a copy)
> 
> This warning seems to be issued when 'rename' is used. Yet, it still mention 'hg copy'.
> It also have an issue similar to the one pointed for copy previously. It point to --after while the user have not expressed any '--after' wish in the original command.

Sigh. Yep. I'll see if I can fix this too.

> 
>>   moving d1/d11/a1 to d2/d11/a1 (glob)
>>   $ hg status -C
>>   A d2/a
>> @@ -370,6 +371,7 @@ attempt to overwrite an existing file
>>   $ echo "ca" > d1/ca
>>   $ hg rename d1/ba d1/ca
>>   d1/ca: not overwriting - file exists
>> +  (hg copy --after to record the copy)
> 
> ditto
> 
>>   $ hg status -C
>>   ? d1/ca
>>   $ hg update -C
>> @@ -393,6 +395,7 @@ attempt to overwrite an existing broken
>>   $ ln -s ba d1/ca
>>   $ hg rename --traceback d1/ba d1/ca
>>   d1/ca: not overwriting - file exists
>> +  (hg copy --after to record the copy)
> 
> ditto.
> 
> -- 
> Pierre-Yves David