Re: [RFC PATCH v2 3/4] grep: honor sparse checkout patterns

[Elijah Newren <newren@gmail.com>]

On Fri, May 22, 2020 at 7:26 AM Elijah Newren <newren@gmail.com> wrote:
>
> Hi Matheus,
>
> On Thu, May 21, 2020 at 10:49 PM Matheus Tavares Bernardino <matheus.bernardino@usp.br> wrote:
> >
> > On Thu, May 21, 2020 at 2:52 PM Elijah Newren <newren@gmail.com> wrote:
> > >
<snip>
> > Does this seem like a good approach? Or is there another solution that
> > I have not considered? Or even further, should we choose to skip the
> > submodules in excluded paths? My only concern in this case is that it
> > would be contrary to the design in git-sparse-checkout.txt. And the
> > working tree grep and cached grep would differ even on a clean working
> > tree.
>
<snip>
> Anyway, the wording in that file seems to be really important, so
> let's fix it.
>

Let me also try to give a concrete proposal for grep behavior for the
edge cases we've discussed:

git -c sparse.restrictCmds=true grep --recurse-submodules $PATTERN

This goes through all the files in the index (i.e. all tracked files)
which do not have the SKIP_WORKTREE bit set.  For each of these: If
the file is a symlink, ignore it (like grep currently does).  If the
file is a regular file and is present in the working copy, search it.
If the file is a submodule and it is initialized, recurse into it.

git -c sparse.restrictCmds=true grep --recurse-submodules --cached $PATTERN

This goes through all the files in the index (i.e. all tracked files)
which do not have the SKIP_WORKTREE bit set.  For each of these: Skip
symlinks.  Search regular files.  Recurse into submodules if they are
initialized.

git -c sparse.restrictCmds=true grep --recurse-submodules $REVISION $PATTERN

This goes through all the files in the given revision (i.e. all
tracked files) which match the sparsity patterns (i.e. that would not
have the SKIP_WORKTREE bit set if were we to checkout that commit).
For each of these: Skip symlinks.  Search regular files.  Recurse into
submodules if they are initialized.


Further, for any of these, when recursing into submodules, make sure
to load that submodules' core.sparseCheckout setting (and related
settings) and the submodules' sparsity patterns, if any.

Sound good?

I think this addresses the edge cases we've discussed so far:
interaction between submodules and sparsity patterns, and handling of
files that are still present despite not matching the sparsity
patterns. (Also note that files which are present-despite-the-rules
are prone to be removed by the next `git sparse-checkout reapply` or
anything that triggers a call to unpack_trees(); there's already
multiple things that do and Stolee's proposed patches would add more).
If I've missed edge cases, let me know.


Elijah