Re: [PATCH v1 3/4] rm: expand the index only when necessary

On 8/3/2022 10:40 PM, Derrick Stolee wrote:
 > On 8/3/2022 12:51 AM, Shaoxuan Yuan wrote:
 >> Originally, rm a pathspec that is out-of-cone in a sparse-index
 >> environment, Git dies with "pathspec '<x>' did not match any files",
 >> mainly because it does not expand the index so nothing is matched.
 >
 > This paragraph appears to be assuming that we've stopped expanding the
 > sparse index already. It might be worthwhile to rewrite this to say
 > "Before integrating 'git rm' with the sparse index, we need to..." or
 > something like that.

I have absolutely no idea why I wrote this paragraph this way, maybe I was zoning out composing it. Will fix.

 >> Remove the `ensure_full_index()` method so `git-rm` does not always
 >> expand the index when the expansion is unnecessary, i.e. when
 >> <pathspec> does not have any possibilities to match anything outside
 >> of sparse-checkout definition.
 >>
 >> Expand the index when the <pathspec> needs an expanded index, i.e. the
 >> <pathspec> contains wildcard that may need a full-index or the
 >> <pathspec> is simply outside of sparse-checkout definition.
 >>
 >> Signed-off-by: Shaoxuan Yuan <shaoxuan.yuan02@gmail.com>
 >> ---
 >>  builtin/rm.c | 5 +++--
 >>  1 file changed, 3 insertions(+), 2 deletions(-)
 >>
 >> diff --git a/builtin/rm.c b/builtin/rm.c
 >> index 84a935a16e..58ed924f0d 100644
 >> --- a/builtin/rm.c
 >> +++ b/builtin/rm.c
 >> @@ -296,8 +296,9 @@ int cmd_rm(int argc, const char **argv, const 
char *prefix)
 >>
 >>      seen = xcalloc(pathspec.nr, 1);
 >>
 >> -    /* TODO: audit for interaction with sparse-index. */
 >> -    ensure_full_index(&the_index);
 >> +    if (pathspec_needs_expanded_index(&the_index, &pathspec))
 >> +        ensure_full_index(&the_index);
 >> +
 >>      for (i = 0; i < active_nr; i++) {
 >>          const struct cache_entry *ce = active_cache[i];
 >
 > Looking back on the tests in patch 1, I don't see any tests that really
 > emphasize the kinds of pathspecs that could not ever integrate with the
 > sparse index. They are all of the form "folder1/*" or similar, making it
 > be something that could be seen as a prefix match. Such a pattern _could_
 > be integrated carefully with the sparse index.
 >
 > Instead, something like `git rm "*/a"` would be much harder to integrate
 > with the sparse index. Could we add a test (in this patch) that checks
 > that kind of case. That would also help justify this as its own patch and
 > not squashed with patch 4.

Makes sense. Will fix.

-- Thanks, Shaoxuan