Newlib shares large parts of <sys/cdefs.h> with FreeBSD and received this bug report: https://sourceware.org/pipermail/newlib/2023/020400.html 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 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__ >= 199901 #define __restrict restrict #elif !__GNUC_PREREQ__(2, 95) #define __restrict #endif
A commit in branch main references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=15876d9fd83fdfa7d541ea747eb40faeade975d2 commit 15876d9fd83fdfa7d541ea747eb40faeade975d2 Author: Sebastian Huber <sebastian.huber@embedded-brains.de> AuthorDate: 2023-08-06 13:27:27 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2023-08-06 21:09:52 +0000 sys/cdefs.h: fix for use __restrict in C++ Newlib shares large parts of <sys/cdefs.h> with FreeBSD and received this bug report: https://sourceware.org/pipermail/newlib/2023/020400.html 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 Rewrite the logic in the header so that __restrict is kept alone when available. PR: 272723 MFC after: 1 week sys/sys/cdefs.h | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-)
A commit in branch stable/13 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=4e94219d55824b19693287052edd8a1da76e3541 commit 4e94219d55824b19693287052edd8a1da76e3541 Author: Sebastian Huber <sebastian.huber@embedded-brains.de> AuthorDate: 2023-08-06 13:27:27 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2023-08-13 04:35:41 +0000 sys/cdefs.h: fix for use __restrict in C++ PR: 272723 (cherry picked from commit 15876d9fd83fdfa7d541ea747eb40faeade975d2) sys/sys/cdefs.h | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-)