Re: [PATCH v3 02/10] xdiff: use ptrdiff_t for dstart/dend

From: Junio C Hamano <gitster@pobox.com>
Date: Nov 11, 2025, 22:23 UTC
Message-ID: <xmqqms4sus2w.fsf@gitster.g>
In-Reply-To: <52e3f589b1ce25085921453eea14b9c9d7c8f362.1762890152.git.gitgitgadget@gmail.com>

"Ezekiel Newren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Ezekiel Newren <ezekielnewren@gmail.com>
>
> ptrdiff_t is appropriate for dstart and dend because they both describe
> positive or negative offsets relative to a pointer.

Makes sense.

> A future patch will move these fields to a different struct. Moving
> them to the end of xdfile_t now, means the field order of xdfile_t will
> be disturbed less.

If these members will be gone from this struct, it wouldn't make any difference in the end. I am not sure what you mean by "disturbed less". Right now there is a gap between changed and nrec members, and at some later point, these two members may be adjacent with each other. I do not think it would make that much difference if they become adjacent after this step [02/10], after step [10/10], or in a separate series (xdiff-cleanup-3?).

Show 21 quoted lines

> Signed-off-by: Ezekiel Newren <ezekielnewren@gmail.com>
> ---
>  xdiff/xtypes.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/xdiff/xtypes.h b/xdiff/xtypes.h
> index f145abba3e..7c8c057bca 100644
> --- a/xdiff/xtypes.h
> +++ b/xdiff/xtypes.h
> @@ -47,10 +47,10 @@ typedef struct s_xrecord {
>  typedef struct s_xdfile {
>  	xrecord_t *recs;
>  	long nrec;
> -	long dstart, dend;
>  	bool *changed;
>  	long *rindex;
>  	long nreff;
> +	ptrdiff_t dstart, dend;
>  } xdfile_t;
>  
>  typedef struct s_xdfenv {