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From: Sebastian Huber <sebastian.huber@embedded-brains.de>
To: Bruno De Fraine <Bruno.DeFraine@synopsys.com>,
	"newlib@sourceware.org" <newlib@sourceware.org>
Subject: Re: newlib header breaks restricted pointers in C++
Date: Tue, 25 Jul 2023 19:46:18 +0200	[thread overview]
Message-ID: <3126b987-ca19-97f6-9c7a-06243add9354@embedded-brains.de> (raw)
In-Reply-To: <ZMAH45R5OHFuUKrz@calimero.vinschen.de>

On 25.07.23 19:35, Corinna Vinschen wrote:
> Hi Bruno,
> 
> On Jul 24 22:23, Bruno De Fraine wrote:
>> Hello,
>>
>> As an extension, GCC and clang offer C99-style restricted pointers in C++ mode:
>> https://gcc.gnu.org/onlinedocs/gcc/Restricted-Pointers.html
>>
>> We notice that this extension is broken when including newlib headers: restricted pointers are treated as ordinary pointers.
>>
>> We traced this to the following section of newlib/libc/include/sys/cdefs.h:
>>
>>    /*
>>     * GCC 2.95 provides `__restrict' as an extension to C90 to support the
>>     * C99-specific `restrict' type qualifier.  We happen to use `__restrict' as
>>     * a way to define the `restrict' type qualifier without disturbing older
>>     * software that is unaware of C99 keywords.
>>     */
>>    #if !(__GNUC__ == 2 && __GNUC_MINOR__ == 95)
>>    #if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901
>>    #define	__restrict
>>    #else
>>    #define	__restrict	restrict
>>    #endif
>>    #endif
>>
>> While the GCC __restrict extension was indeed introduced in GCC 2.95, it is not limited to this version; the extension is also not limited to C90:
>> https://gcc.gnu.org/gcc-2.95/c++features.html
> Either way, the above has been taken from FreeBSD, and it is still,
> as of today, the same expression as used in FreeBSDs sys/cdefs.h
> file.
> 
> Seb, any input on this?

I added a FreeBSD bug report:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=272723

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  reply	other threads:[~2023-07-25 17:46 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-24 22:23 Bruno De Fraine
2023-07-25 17:35 ` Corinna Vinschen
2023-07-25 17:46   ` Sebastian Huber [this message]
2023-07-25 18:48     ` Corinna Vinschen
2023-07-25 23:48       ` Steven J Abner
2023-07-27  9:00         ` Corinna Vinschen
2023-07-28 14:15           ` Sebastian Huber
2023-07-28 14:42             ` Joel Sherrill
2023-07-31 11:04       ` Bruno De Fraine

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