From patchwork Thu Aug 31 21:09:22 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 9932901 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 718126022E for ; Thu, 31 Aug 2017 21:09:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6526A22BF1 for ; Thu, 31 Aug 2017 21:09:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 59B9423B32; Thu, 31 Aug 2017 21:09:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2DDB623B23 for ; Thu, 31 Aug 2017 21:09:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751415AbdHaVJZ (ORCPT ); Thu, 31 Aug 2017 17:09:25 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:53286 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751276AbdHaVJY (ORCPT ); Thu, 31 Aug 2017 17:09:24 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.87 #1 (Red Hat Linux)) id 1dnWiI-0002d3-L7; Thu, 31 Aug 2017 21:09:22 +0000 Date: Thu, 31 Aug 2017 22:09:22 +0100 From: Al Viro To: Linus Torvalds Cc: Josh Poimboeuf , Sparse Mailing-list Subject: Re: Sparse preprocessing bug with zero-arg variadic macros Message-ID: <20170831210922.GA9227@ZenIV.linux.org.uk> References: <20170831133400.zjeaxhf25rbdftic@treble> <20170831205433.GQ5426@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20170831205433.GQ5426@ZenIV.linux.org.uk> User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-sparse-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sparse@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Thu, Aug 31, 2017 at 09:54:33PM +0100, Al Viro wrote: > What a mess... Note that for non-vararg it *is* the right interpretation > (with #define A(x) [x] we will have A() interpreted as "empty token sequence > as the only argument", not "no arguments given"). For vararg case we > normally do not need to distinguish "not given" and "empty" - the only > thing that cares is exactly the ,## kludge. There with > #define B(x,...) [x,##__VA_ARGS__] > B(1) and B(1,) yield [1] and [1,] resp. And for everything other than > "just ..." we even get it right... > > I see what's going on there; will post a fix in a few. Fix macro argument parsing for (...) case Nasty corner case for the sake of ,##__VA_ARGS__ perversion - for something like #define A(x,...) [x,##__VA_ARGS] we want A(1) to expand to [1] and A(1,) - to [1,]. In other words, "no vararg given" and "vararg empty" are different and need to be distinguished. Unfortunately, in case when there was nothing but vararg we got it wrong - #define A(...) ,##__VA_ARGS ended up with A() interpreted as "one empty argument" (as it would in non-vararg case) rather than "zero arguments". Signed-off-by: Al Viro --- -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/pre-process.c b/pre-process.c index 74414df..8800dce 100644 --- a/pre-process.c +++ b/pre-process.c @@ -296,9 +296,11 @@ static int collect_arguments(struct token *start, struct token *arglist, struct for (count = 0; count < wanted; count++) { struct argcount *p = &arglist->next->count; next = collect_arg(start, p->vararg, &what->pos, p->normal); - arglist = arglist->next->next; if (eof_token(next)) goto Eclosing; + if (p->vararg && wanted == 1 && eof_token(start->next)) + break; + arglist = arglist->next->next; args[count].arg = start->next; args[count].n_normal = p->normal; args[count].n_quoted = p->quoted;