Date: Tue, 25 Jul 2023 17:45:43 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 272723] <sys/cdefs.h> header breaks restricted pointers in C++ Message-ID: <bug-272723-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D272723 Bug ID: 272723 Summary: <sys/cdefs.h> header breaks restricted pointers in C++ Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: misc Assignee: bugs@FreeBSD.org Reporter: sebastian.huber@embedded-brains.de Newlib shares large parts of <sys/cdefs.h> with FreeBSD and received this b= ug report: https://sourceware.org/pipermail/newlib/2023/020400.html As an extension, GCC and clang offer C99-style restricted pointers in C++ m= ode: 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__ =3D=3D 2 && __GNUC_MINOR__ =3D=3D 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 This is a suggestion how the logic in the header could be rewritten: /* * We use `__restrict' as a way to define the `restrict' type qualifier * without disturbing older software that is unaware of C99 keywords. * GCC also provides `__restrict' as an extension to support C99-style * restricted pointers in other language modes. */ #if defined(__STDC_VERSION__) && __STDC_VERSION__ >=3D 199901 #define __restrict restrict #elif !__GNUC_PREREQ__(2, 95) #define __restrict #endif --=20 You are receiving this mail because: You are the assignee for the bug.=
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