Re: diff --check is stupid about blank lines

From: Jeff King <peff@peff.net>
Date: Aug 20, 2008, 17:28 UTC
Message-ID: <20080820172825.GC27773@sigill.intra.peff.net>
In-Reply-To: <20080820140517.GA1304@atjola.homenet>

On Wed, Aug 20, 2008 at 04:05:17PM +0200, Björn Steinbrink wrote:

> diff --check triggers not only for blank lines at the end of the file,
> but also at the end of the changes. That seems broken to me, unless you
> really dislike empty lines.

Hmm, yes, that seems wrong. The problem seems to be the conditional at diff.c:1622:

        if ((data.ws_rule & WS_TRAILING_SPACE) &&
            data.trailing_blanks_start) {
                fprintf(o->file, "%s:%d: ends with blank lines.\n",
                        data.filename, data.trailing_blanks_start);
                data.status = 1; /* report errors */
        }

that should probably be "if we care about trailing space, and the last thing we saw was a trailing blank, _and_ the last hunk adds to end-of-file, then...". However, I'm not sure what is the best way to get that information out of xdiff. Is there a "this hunk hits eof" signal anywhere? Is there a definitive line count we could use to calculate that it is in the chunk of final lines in the file?

-Peff