X-Authentication-Warning: delorie.com: mail set sender to djgpp-bounces using -f
X-Recipient: djgpp AT delorie DOT com
X-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=20161025;
        h=subject:to:references:from:message-id:date:user-agent:mime-version
         :in-reply-to:content-language:content-transfer-encoding;
        bh=ryKVkA+QkE9/suYHfI/nhFDuHCE98QgY0zaMGv38yK8=;
        b=kOhysAgyN5St4cX/O8MKssp2B9lqqauVnQ6T1KczMPjDumGJCNzCQ8sQ3uvk9mtcU7
         H46vn+HPgLPrpM/tvH2SVSDCZ8FYPTLDh2fqE3c4fNLNdVP9OOCORxmjrsDjC8OMQhsf
         iHOEEFTKuHbhAHWVkvR9AgFBDOkfKWp/+qzVX8plmoPc4LY+oXBkSYkvCJVbG/VKrjRa
         C7KPnMzsWGN5j+74C2XfV9VfWzXCpwM1zuetOfP0V0SgAgjnlWod6yma2sVmYwx26GYx
         dpQRzdzIrMSdkRTnKaPGWuxqO44V5HmiFNHsF4BgqMJ/X950ge629kZsVxtm+FnkpTW9
         ACgw==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=1e100.net; s=20161025;
        h=x-gm-message-state:subject:to:references:from:message-id:date
         :user-agent:mime-version:in-reply-to:content-language
         :content-transfer-encoding;
        bh=ryKVkA+QkE9/suYHfI/nhFDuHCE98QgY0zaMGv38yK8=;
        b=Jc1PZ3hqbhBsl0p9tnojLjXWEy+UkBz2kvi26YWFfpb3EXIWe1ctMZkTIU+PtDOHwq
         V7tIiY8Lw2Nq1qnH81X4YTxCJ6VUr988rVltwHghJHGteAQpFlDNH99yVhr2oLRExv0P
         P4+mFPN//Fm4QP1/f09ldP69yOH5NiS2Rhy3Q1Wg2r89UjzQzHdZ2OwDHT11OA82R9h0
         O9cjo72Xhyy9DZNneDC85kQtgIhkBcm+VNmZte50Fg49Xzsu1CSvurde4d0viIAJWKAZ
         Ah0kT/4+QIQCyaYboS3ve9+9ZKPK5cCXjruqEwC1afRD1hipU4W+ETvTpBIB08YBKYHI
         dnpw==
X-Gm-Message-State: AOAM5320ePDPJMQDZucxk2+JlgRy2P/aS0vQQlLCknLRGRFbezgdeZOz
	Hk9UY9u1ECLMMv+O6piFZ9X6teEqbWc=
X-Google-Smtp-Source: ABdhPJwiugK9MUG+tlV1lzmo/FnsxaDwlb/vdrRFMC4MF6dMUN9L5a+f7fjRpU7DvMvunpFHtAvfmQ==
X-Received: by 2002:a19:4941:: with SMTP id l1mr3174190lfj.136.1607626519664;
        Thu, 10 Dec 2020 10:55:19 -0800 (PST)
Subject: Re: Difficulties compiling libc from repository using gcc 10.N.0
To: djgpp AT delorie DOT com
References: <5FD1FEA1 DOT 7010304 AT gmx DOT de>
 <8816d501-9f33-4d68-4235-1935a83580f6 AT gmail DOT com>
 <CAA2C=vACivjbYiU7yVpyFdzKjjKB10E1tvqShLPQ6i31cuKrDA AT mail DOT gmail DOT com>
 <111383e4-b3db-f346-b71c-749dee17dc9e AT gmail DOT com>
 <CAA2C=vDL+YWHssNteT71jUNxYAJkxwiNXrKp1O618tY6bHHcxg AT mail DOT gmail DOT com>
 <831rfx4ixg DOT fsf AT gnu DOT org>
From: "J.W. Jagersma (jwjagersma AT gmail DOT com) [via djgpp AT delorie DOT com]" <djgpp AT delorie DOT com>
Message-ID: <6371c322-a0ad-b85a-1ccc-1bdfff4a8d87@gmail.com>
Date: Thu, 10 Dec 2020 19:55:11 +0100
User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101
 Thunderbird/78.5.1
MIME-Version: 1.0
In-Reply-To: <831rfx4ixg.fsf@gnu.org>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Reply-To: djgpp AT delorie DOT com
Errors-To: nobody AT delorie DOT com
X-Mailing-List: djgpp AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com
Precedence: bulk

On 2020-12-10 19:25, Eli Zaretskii (eliz AT gnu DOT org) [via djgpp AT delorie DOT com] wrote:
>> From: "Ozkan Sezer (sezeroz AT gmail DOT com) [via djgpp AT delorie DOT com]" <djgpp AT delorie DOT com>
>> Date: Thu, 10 Dec 2020 20:44:01 +0300
>>
>> --- src/debug/fsdb/makefile	27 Sep 1998 17:04:26 -0000	1.3
>> +++ src/debug/fsdb/makefile	10 Dec 2020 17:39:43 -0000
>> @@ -12,6 +12,9 @@ EOBJS += unassmbl.o
>>  
>>  include $(TOP)/../makefile.inc
>>  
>> +#see screen.h as to why this is needed
>> +CFLAGS += -fcommon
>> +
> 
> This part looks OK.
> 
>> --- src/libc/ansi/stdlib/exit.c	2 May 2015 07:32:10 -0000	1.9
>> +++ src/libc/ansi/stdlib/exit.c	10 Dec 2020 17:39:43 -0000
>> @@ -15,7 +15,7 @@
>>  
>>  struct __atexit *__atexit_ptr = 0;
>>  
>> -void (*__stdio_cleanup_hook)(void);
>> +extern void (*__stdio_cleanup_hook)(void); /* stdio/stdiohk.c */
> 
> This part I don't understand: are you saying that it is no longer the
> default that a function not explicitly declared 'static' has the
> external linkage?  Why do we need an explicit 'extern' qualifier?
> 
> Thanks.

This only applies to global variables (and __stdio_cleanup_hook here is a
function *pointer*), functions themselves still have implicit external linkage.

I'm not a C language lawyer but this page suggests that it was always an error
to omit 'extern' on global variable declarations.  It just wasn't reported as
such, until now:

https://gcc.gnu.org/gcc-10/porting_to.html