Date: Thu, 24 Aug 2017 23:32:07 -0700 From: Mark Millard <markmi@dsl-only.net> To: imp@FreeBSD.org, svn-src-head@freebsd.org, FreeBSD Current <freebsd-current@freebsd.org>, FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org>, freebsd-hackers <freebsd-hackers@freebsd.org> Subject: Re: svn commit: r322875 - head/sys/dev/nvme Message-ID: <1C5A448F-C91A-4599-8500-E4E46E6F5205@dsl-only.net>
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> Author: imp > Date: Fri Aug 25 04:33:06 2017 > New Revision: 322875 > URL:=20 > https://svnweb.freebsd.org/changeset/base/322875 >=20 >=20 > Log: > Use _Static_assert > =20 > These files are compiled in userland too, so we can't use = sys/systm.h > and rely on CTASSERT. Switch to using _Static_assert instead. > =20 > MFC After: 3 days > Sponsored by: Netflix >=20 > Modified: > head/sys/dev/nvme/nvme.h > head/sys/dev/nvme/nvme_util.c As I remember _Static_assert is from C11, not the older C99. As I understand head/sys/dev/nvme/nvme.h use by C++ code could now reject attempts to use _Static_assert . There have been at least one old bugzilla report for such. An example is 205453 (back around 2015-Dec). =46rom back then: > # more main.cc > #include "/usr/include/sys/cdefs.h" > _Static_assert(1,"Test"); > int main(void) > { > return 0; > } >=20 > For example: >=20 > # g++49 main.cc > main.cc:2:15: error: expected constructor, destructor, or type = conversion before '(' token > _Static_assert(1,"Test"); > . . . > g++49, g++5, and powerpc64-portbld-freebsd11.0-g++ all reject the = above source the same way that libcxxrt/guard.cc compiles are rejected = during powerpc64-portbld-freebsd11.0-g++ based buildworld lib32 -m32 = compiles.=20 >=20 > gcc49, gcc5, and powerpc64-portbld-freebsd11.0-gcc all accept the = above instead (when in main.c instead of main.cc so it is handle as C = code), with or without the include. _Static_assert is specific to C11 = and is not part of C++. It takes explicit definitions to make the syntax = acceptable as C++. >=20 > Note: clang++ (3.7) accepts the use of the C11 _Static_assert, with or = without the include, going well outside the C++ language definition. >=20 > . . . >=20 > Fixed in r297299 . (The context was a C++ file head/contrib/libcxxrt/guard.cc so C++'s static_assert was used instead and -std=3Dc++11 was added for the library in question [libcxxrt].) Unless head/sys/dev/nvme/nvme.h is not to be used from C++ code: use of _Static_assert in the header would appear to be a problem. =3D=3D=3D Mark Millard markmi at dsl-only.net
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