Re: [PATCH 1/3] xdiff: -W: relax end-of-file function detection

From: René Scharfe <l.s.r@web.de>
Date: Jan 13, 2017, 17:49 UTC
Message-ID: <23ca90e5-90a4-a03f-e51e-c82ebc75c16f@web.de>
In-Reply-To: <1484324112-17773-1-git-send-email-vegard.nossum@oracle.com>

Am 13.01.2017 um 17:15 schrieb Vegard Nossum:

Show 6 quoted lines

> When adding a new function to the end of a file, it's enough to know
> that 1) the addition is at the end of the file; and 2) there is a
> function _somewhere_ in there.
>
> If we had simply been changing the end of an existing function, then we
> would also be deleting something from the old version.

That makes sense, thanks.

Show 8 quoted lines

> This fixes the case where we add e.g.
>
> 	// Begin of dummy
> 	static int dummy(void)
> 	{
> 	}
>
> to the end of the file.

Without this patch the unchanged function before the added lines is shown in its entirety as (uncalled for) context.

Show 24 quoted lines

>
> Cc: René Scharfe <l.s.r@web.de>
> Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
> ---
>  xdiff/xemit.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
>
> diff --git a/xdiff/xemit.c b/xdiff/xemit.c
> index 7389ce4..8c88dbd 100644
> --- a/xdiff/xemit.c
> +++ b/xdiff/xemit.c
> @@ -183,16 +183,14 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
>
>  				/*
>  				 * We don't need additional context if
> -				 * a whole function was added, possibly
> -				 * starting with empty lines.
> +				 * a whole function was added.
>  				 */
> -				while (i2 < xe->xdf2.nrec &&
> -				       is_empty_rec(&xe->xdf2, i2))
> +				while (i2 < xe->xdf2.nrec) {
> +					if (match_func_rec(&xe->xdf2, xecfg, i2,
> +						dummy, sizeof(dummy)) >= 0)

Nit: I don't like the indentation here.  Giving "dummy" its own line is 
also not exactly pretty, but at least would allow the parameters to be 
aligned on the opening parenthesis.

Show 11 quoted lines

> +						goto post_context_calculation;
>  					i2++;
> -				if (i2 < xe->xdf2.nrec &&
> -				    match_func_rec(&xe->xdf2, xecfg, i2,
> -						   dummy, sizeof(dummy)) >= 0)
> -					goto post_context_calculation;
> +				}
>
>  				/*
>  				 * Otherwise get more context from the
>