Re: [PATCH 7/8] checkout: allow ignoring unmatched pathspec

> On Sun, Dec 9, 2018 at 12:05 PM Thomas Gummerer <t.gummerer@gmail.com> wrote:
> >
> > Currently when 'git checkout -- <pathspec>...' is invoked with
> > multiple pathspecs, where one or more of the pathspecs don't match
> > anything, checkout errors out.
> >
> > This can be inconvenient in some cases, such as when using git
> > checkout from a script.  Introduce a new --ignore-unmatched option,
> > which which allows us to ignore a non-matching pathspec instead of
> > erroring out.
> >
> > In a subsequent commit we're going to start using 'git checkout' in
> > 'git stash' and are going to make use of this feature.
> 
> This makes sense, but seems incomplete.  But to explain it, I think
> there's another bug I need to demonstrate first because it's related
> on builds on it.  First, the setup:
> 
>   $ echo foo >subdir/newfile
>   $ git add subdir/newfile
>   $ echo bar >>subdir/newfile
>   $ git status
>   On branch A
>   Changes to be committed:
>     (use "git reset HEAD <file>..." to unstage)
> 
>       new file:   subdir/newfile
> 
>   Changes not staged for commit:
>     (use "git add <file>..." to update what will be committed)
>     (use "git checkout -- <file>..." to discard changes in working directory)
> 
>       modified:   subdir/newfile
> 
> Now, does it do what we expect?
> 
>   $ git checkout HEAD -- subdir/newfile
>   error: pathspec 'subdir/newfile' did not match any file(s) known to git
> 
> This is the old overlay behavior; kinda lame, but you made no claims
> about fixing the default behavior.  What about with your new option?
> 
>   $ git checkout --no-overlay HEAD -- subdir
>   $ git status
>   On branch A
>   nothing to commit, working tree clean
> 
> Yes, the feature seems to work as advertised.  However, let's try
> again with a different variant:
> 
>   $ echo foo >subdir/newfile
>   $ git checkout --no-overlay HEAD -- subdir
>   $ git status
>   On branch A
>   Untracked files:
>     (use "git add <file>..." to include in what will be committed)
> 
>       subdir/newfile
> 
> Why is the file ignored and left there?  Also:
> 
>   $ git checkout --no-overlay HEAD -- subdir/newfile
>   error: pathspec 'subdir/newfile' did not match any file(s) known to git
> 
> That seems wrong to me.

>                          The point of no-overlay is to make it match
> HEAD, and while subdir/newfile doesn't exist in HEAD or the index it
> does match in the working tree so the intent is clear. But let's say
> that the user did go ahead and specify your new flag:
> 
> 
>   $ git checkout --no-overlay --ignore-unmatch HEAD -- subdir/newfile
>   $ git status
>   On branch A
>   Untracked files:
>     (use "git add <file>..." to include in what will be committed)
> 
>       subdir/newfile
> 
>   nothing added to commit but untracked files present (use "git add" to track)
> 
> So now it avoids erroring out when the user does more work than
> necessary, but it still misses appropriately cleaning up the file.