Re: [PATCH 2/2] convert trivial uses of strncmp() to skip_prefix()

From: Jeff King <peff@peff.net>
Date: Jan 7, 2023, 13:33 UTC
Message-ID: <Y7l0mq6khtlgxGca@coredump.intra.peff.net>
In-Reply-To: <Y7lzFG9gyDrOE4Xt@coredump.intra.peff.net>

On Sat, Jan 07, 2023 at 08:26:45AM -0500, Jeff King wrote:

> Note in the case in ws.c that to get rid of the magic number "9"
> completely, we also switch out "len" for recomputing the pointer
> difference. These are equivalent because "len" is always "ep - string".

By the way, one thing I noticed about this parse_whitespace_rule() function is that it's very loose about its matching. It does:

        for (i = 0; i < ARRAY_SIZE(whitespace_rule_names); i++) {
                if (strncmp(whitespace_rule_names[i].rule_name,
                            string, len))
                        continue;
		...we matched...
		break;
	}

So it will prefix-match any of the options, even if there are ambiguities. E.g.:

  git -c core.whitespace=-t show

will turn off "trailing-space", even though it would also match "tab-in-indent". It would be easy enough to fix it to require the whole name, but I wasn't sure if this prefix-matching was supposed to be a feature (it doesn't seem to be documented anywhere, though).

-Peff