Re: [PATCH v5 1/3] apply: allow "new file" patches on i-t-a entries

> diff-files recently changed to treat changes to paths marked "intent to
> add" in the index as new file diffs rather than diffs from the empty
> blob.  However, apply refuses to apply new file diffs on top of existing
> index entries, except in the case of renames. This causes "git add -p",
> which uses apply, to fail when attempting to stage hunks from a file
> when intent to add has been recorded.
> 
> This changes the logic in check_to_create() which checks if an entry
> already exists in an index in two ways: first, we only search for an
> index entry at all if ok_if_exists is false; second, we check for the
> CE_INTENT_TO_ADD flag on any index entries we find and allow the apply
> to proceed if it is set.

> 
> Helped-by: Junio C Hamano <gitster@pobox.com>
> Signed-off-by: Raymond E. Pasco <ray@ameretat.dev>
> ---
>   apply.c | 11 +++++++----
>   1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/apply.c b/apply.c
> index 8bff604dbe..4cba4ce71a 100644
> --- a/apply.c
> +++ b/apply.c
> @@ -3747,10 +3747,13 @@ static int check_to_create(struct apply_state *state,
>   {
>   	struct stat nst;
>   
> -	if (state->check_index &&
> -	    index_name_pos(state->repo->index, new_name, strlen(new_name)) >= 0 &&
> -	    !ok_if_exists)
> -		return EXISTS_IN_INDEX;
> +	if (state->check_index && !ok_if_exists) {
> +		int pos = index_name_pos(state->repo->index, new_name, strlen(new_name));
> +		if (pos >= 0 &&
> +		    !(state->repo->index->cache[pos]->ce_flags & CE_INTENT_TO_ADD))
> +			return EXISTS_IN_INDEX;
> +	}
> +
>   	if (state->cached)
>   		return 0;
>   
>