X-Recipient: archive-cygwin AT delorie DOT com
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 16FD33857C6D
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1635343660;
	bh=eVnTsRbUuuFQnGxyldo0GykfJsqwsDEgQniUGf0qvnI=;
	h=References:In-Reply-To:Date:Subject:To:List-Id:List-Unsubscribe:
	 List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:
	 From;
	b=Q7mH2zniJgQVKQ7UYgKb5ZiuD+pGI5tx0wDp2dda+7IyqkBhgMutyjZtXz8v3i8VT
	 /jdUCgbZ/sIPa2qtZvOFQd/y0ruOh0GYKBKbHBM/uZoPNRXdafDTeIij1ymfGdPH30
	 UUWJWzWZBt3qGNgxKhdC+kvwqJ7hmAhtCqDKg6pA=
X-Original-To: cygwin AT cygwin DOT com
Delivered-To: cygwin AT cygwin DOT com
DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 2C5133858C27
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
 d=1e100.net; s=20210112;
 h=x-gm-message-state:mime-version:references:in-reply-to:from:date
 :message-id:subject:to;
 bh=0INt6JFs17YOPndprvjh9JHhcsHrWE/U55M8MK1BH/8=;
 b=TNG2n4KdfWHtl8tdCZvzSO6DgsTt8W7UcvakZz+zHV4yIZW7wpQuGiCvzq4O+pPO7l
 XBUs2k71p5M0/O46tDbK10R24tk8etqU3JoURyT6wNZnlc2Re7dGIRXrruEZLrDvaFA4
 vjicwqc5m5IIlJZLTalKBCyn1Iwgg7+wx//ENG3ypz+84HtdE4pEqucGvjsinbXgO/AQ
 69QhQ8T4hKWeYOebojgVl536Vk9PCtaJvOeWdLZ+rmri376PgoAmnY20Kb4TcBr2691C
 HWMYPhe3OulbXtmjlAUlWfO7UM27sq0E8b1ZBCBwOpdp052wRuof4n9n5LNmF4yb25pJ
 lqew==
X-Gm-Message-State: AOAM533JDHpSwLxaJrRzTPEoYc//1Y6GO+DOiJ71Gk8f07qTujKbpP/l
 RqZNH7nwK5ORmRE7ZsxB4i4S37tb41BIHj1+Ov0+kdR2WI4=
X-Google-Smtp-Source: ABdhPJyS9t4m2j92QLLMKzyHp74sNyG4XdLs38TsmdfhZU7MnOeXoXVDHnVmb9qFsqApAxmkyEoA0VetJAisVWd/fIY=
X-Received: by 2002:a05:6102:e06:: with SMTP id
 o6mr30405739vst.53.1635343625677; 
 Wed, 27 Oct 2021 07:07:05 -0700 (PDT)
MIME-Version: 1.0
References: <248361fa-f16d-cebb-eefe-be78e09f4c10 AT towo DOT net>
 <530117425 DOT 2623944 DOT 1635332143429 AT mail DOT yahoo DOT com>
In-Reply-To: <530117425.2623944.1635332143429@mail.yahoo.com>
Date: Wed, 27 Oct 2021 23:06:54 +0900
Message-ID: <CAAr43iPPAMTUnJzOa=2B3R1Z84SWaDbrYEebLhqJDBnhn475UA@mail.gmail.com>
Subject: Re: gcc 11 weird bug
To: "cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
X-Spam-Status: No, score=-0.9 required=5.0 tests=BAYES_00, DKIM_SIGNED,
 DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,
 SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on
 server2.sourceware.org
X-BeenThere: cygwin AT cygwin DOT com
X-Mailman-Version: 2.1.29
List-Id: General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Archive: <https://cygwin.com/pipermail/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe: <https://cygwin.com/mailman/listinfo/cygwin>,
 <mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
From: Joel Rees via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Joel Rees <joel DOT rees AT gmail DOT com>
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Sender: "Cygwin" <cygwin-bounces+archive-cygwin=delorie DOT com AT cygwin DOT com>

On Wed, Oct 27, 2021 at 7:56 PM Hannes Domani via Cygwin
<cygwin AT cygwin DOT com> wrote:
>
>  Am Mittwoch, 27. Oktober 2021, 11:19:19 MESZ hat Thomas Wolff <towo AT towo DOT net> Folgendes geschrieben:
>
> > I noticed that mintty did not compile anymore after upgrade to gcc 11,
> > but only on cygwin 32-bit.
> > I tried to minimize the test case as much as possible without having the
> > bug vanish, to the attached standalone file.
> > Compile this with
> > cc -O2 -Wall -Werror m0.c
> > and it gives a false positive warning about possible uninitialized data
> > usage.
> > While data flow analysis is not perfect, it is weird that this used to
> > happen on 32 bit but not on 64 bit.
> > Meanwhile, after updating some other packages (not sure which), but
> > still the same gcc version, the report on the test case also happens on
> > 64 bit, while the original, unstripped file, as part of mintty, still
> > works without error on 64 bit, which is even weirder.
> > I have not yet had the opportunity to test this on Linux, sorry, so I'm
> > reporting it here.
> > Thomas
>
> If you mean this warning:
>
> m0.c: In function 'do_bidi':
> m0.c:256:12: error: '*types[0]' may be used uninitialized [-Werror=maybe-uninitialized]
>
> This warning is correct, because as far as gcc is concerned, count could
> be 0, and in this case types[0] will be uninitialized (and doesn't even
> exist, since it's declared as 'uchar types[count];').

I'm not familiar with cygwin repositories, where can I find the source for this?

I'm looking at the warnings and wondering if it's from a "flexible
array" declaration in a typedef.

-- 
Joel Rees

http://reiisi.blogspot.jp/p/novels-i-am-writing.html

-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple