Re: [PATCH v2 1/2] filter-branch: stop special-casing $filter_subdir argument

Johannes Sixt wrote:

Thomas Rast schrieb:

quoted

Handling $filter_subdir in the usual way requires a separate case at
every use, because the variable is empty when unused.  Furthermore,
the case for --subdirectory-filter supplies its own --, so the user
cannot provide one himself (though there is also very little point in
doing so).

I understand that this is a preparatory patch, but you seem to argue that
even without the follow-up patch there is a problem. But from your
explanation I do not understand what it is. An example invocation that
shows the problem would be very helpful.

Well, I just observed while writing the patch that you cannot say

  git filter-branch --subdirectory-filter subdir -- --all -- subdir/file

because the --subdirectory-filter supplies its own -- to the rev-list
invocation, i.e., it calls

  git rev-list --all -- subdir/file -- subdir

which filters for a file called --.

I doubt anyone ever needed this operation though, and it can easily be
done in two separate filtering steps.

quoted

@@ -257,15 +257,29 @@ git read-tree || die "Could not seed the index"
 # map old->new commit ids for rewriting parents
 mkdir ../map || die "Could not create map/ directory"
 
+non_ref_args=$(git rev-parse --no-revs --sq "$@")
+dashdash=--
+for arg in "$non_ref_args"; do

At this point $non_ref_args might contain one or more IFS-separatable
words, but if you say "$non_ref_args" here, this loop will be entered
exactly once. But even if you drop the dquotes, the --sq quoting that you
requested from rev-parse bought you nothing.

Hrm.  Ok, so the ".." were clearly in mistake, but why could I remove
the --sq?  Doesn't the shell expand the arguments provided by
$non_ref_args if I use it without quotes nor --sq, so that it might
accidentally expand paths or such?

quoted

+	if test arg = --; then

Did you mean $arg here? Even then this test will succeed only if
$non_ref_args contains exactly one word and that word is '--'. Is that
what you mean?

No, it should find a -- argument to see if we need to supply our own
before the $filter_subdir.

This looks so convoluted; there must be a simpler way to achieve your goal.

I'll try with more 'case's later...  maybe I can at least avoid the
eval.

Thanks for your comments!

-- 
Thomas Rast
trast@{inf,student}.ethz.ch