Re: diff --check is stupid about blank lines

Junio C Hamano [off-list ref] writes:

Jeff King [off-list ref] writes:

quoted

... 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...".

Instead, data.trailing_blanks_start is supposed to be reset to 0 every
time we see non-blank newline, a copied context line, or new hunk.

So if this triggers with -U0 I'd understand, but otherwise I do not see
how.

Ahhh, what idiot wrote the logic for checking trailing blank lines in
checkdiff_consume().

It does not ask for any context lines.  Sheesh.

This should fix it.

diff --git i/diff.c w/diff.c
index 10d5440..5923fe2 100644
--- i/diff.c
+++ w/diff.c

@@ -1628,6 +1628,7 @@ static void builtin_checkdiff(const char *name_a, const char *name_b,
 		xdemitcb_t ecb;
 
 		memset(&xecfg, 0, sizeof(xecfg));
+		xecfg.ctxlen = 1; /* at least one context line */
 		xpp.flags = XDF_NEED_MINIMAL;
 		xdi_diff_outf(&mf1, &mf2, checkdiff_consume, &data,
 			      &xpp, &xecfg, &ecb);