Re: [RFC PATCH] Not computing changed path filter for root commits

["SZEDER Gábor" <szeder.dev@gmail.com>]

On Mon, Sep 11, 2023 at 03:31:56PM -0700, Jonathan Tan wrote:
> SZEDER Gábor suggested [2] that we change the revision walk to read
> changed path filters also for root commits, but I don't think that's
> possible - we have to tie reading changed path filters to when we read
> trees, and right now, we don't seem to read trees when evaluating root
> commits (rev_compare_tree() in revision.c is in the only code path that
> uses changed path filters, and it itself is only called per-parent and
> thus not called for root commits).

When encountering a root commit during a pathspec-limited revision
walk we call rev_same_tree_as_empty() instead of rev_compare_tree().
All that's missing there is checking the Bloom filter and accounting
for false positives.