Re: git-apply does not work in a sub-directory of a Git repository

[Duy Nguyen <pclouds@gmail.com>]

On Thu, Mar 24, 2016 at 11:50 PM, Junio C Hamano <gitster@pobox.com> wrote:
> Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:
>
>>> On Wed, Mar 23, 2016 at 11:55 PM, Junio C Hamano <gitster@pobox.com> wrote:
>>>> The include/exclude mechanism does use wildmatch() but does not use
>>>> the pathspec mechanism (it predates the pathspec machinery that was
>>>> made reusable in places like this).  We should be able to
>>>>
>>>>     $ cd d/e/e/p/d/i/r
>>>>     $ git apply --include=:/ ../../../../../../../patch
>>>>
>>>> to lift this limitation.  IOW, we can think of the use_patch() to
>>>> include only the paths in the subdirectory we are in by default, but
>>>> we can make it allow --include/--exclude command line option to
>>>> override that default.
>>
>> I went with a new option instead of changing --include.
>
> It might be a "workable" band-aid, but would be an unsatisfying UI
> if it were the endgame state.  You do not say "git grep --whole" (by
> the way, "whole" is a bad option name, as you cannot tell "100% of
> *what*" you are referring to--what you are widening is the limit
> based on the location in the directory structure, so the option name
> should have some hint about it, e.g. "full-tree" or something) and
> this command will become an odd-man-out.
>
> I haven't thought things through, but thinking out aloud a few
> points...
>
>   An existing user/script may be working in a subdirectory of a huge
>   working tree and relies on the current behaviour that outside world
>   is excluded by default, and may be passing --exclude to further
>   limit the extent of damage by applying the patch to a subset of
>   paths in the current directory that itself is also huge.  And that
>   use case would not be harmed by such a change.
>
>   On the other hand, an existing user/script would not be passing an
>   "--include" that names outside the current subdirectory to force
>   them to be included, because it is known for the past 10 years not
>   to have any effect at all.

Real-world .gitignore patterns have taught me that even if it does not
have any effect, it might still be present in some scripts, waiting
for a chance to bite me.

> So a better alternative may be to conditionally disable the "Paths
> outside are not touched regardless of --include" logic, i.e. we
> exclude paths outside by default just as before, but if there is at
> least one explicit "--include" given, we skip this "return 0".
>
> That way, we do not have to commit to turning --include/--exclude to
> pathspec (which I agree is a huge change in behaviour that may not
> be a good idea) and we do not have to add "--full-tree" that is only
> understood by "apply" but not other commands that operate on the
> current directory by default.

But your suggestion is good and I can't think of any better. We could
introduce pathspec as ftiler after "--", but it does not look elegant,
and it overlaps with --include/--exclude.

Perhaps we can start to warn people if --include is specified but has
no effect for a cycle or two, then we can do as you suggested?
-- 
Duy