Re: [PATCH 4/7] unpack-trees: do not mark a dirty path with SKIP_WORKTREE

> From: Elijah Newren <newren@gmail.com>
> 
> If a path is dirty, removing from the working tree risks losing data.
> As such, we want to make sure any such path is not marked with
> SKIP_WORKTREE.  While the current callers of this code detect this case
> and re-populate with a previous set of sparsity patterns, we want to
> allow some paths to be marked with SKIP_WORKTREE while others are left
> unmarked without it being considered an error.  The reason this
> shouldn't be considered an error is that SKIP_WORKTREE has always been
> an advisory-only setting; merge and rebase for example were free to
> materialize paths and clear the SKIP_WORKTREE bit in order to accomplish
> their work even though they kept the SKIP_WORKTREE bit set for other
> paths.  Leaving dirty working files in the working tree is thus a
> natural extension of what we have already been doing.
> 
> Signed-off-by: Elijah Newren <newren@gmail.com>
> ---
>  unpack-trees.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/unpack-trees.c b/unpack-trees.c
> index 853d843b17a..8f10ac91ce1 100644
> --- a/unpack-trees.c
> +++ b/unpack-trees.c
> @@ -504,8 +504,11 @@ static int apply_sparse_checkout(struct index_state *istate,
>  		 * also stat info may have lost after merged_entry() so calling
>  		 * verify_uptodate() again may fail
>  		 */
> -		if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
> +		if (!(ce->ce_flags & CE_UPDATE) &&
> +		    verify_uptodate_sparse(ce, o)) {
> +			ce->ce_flags &= ~CE_SKIP_WORKTREE;
>  			return -1;
> +		}
>  		ce->ce_flags |= CE_WT_REMOVE;
>  		ce->ce_flags &= ~CE_UPDATE;
>  	}