Date: Fri, 28 Apr 2017 08:33:22 +1000 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Gleb Smirnoff <glebius@freebsd.org> Cc: Ngie Cooper <yaneurabeya@gmail.com>, Ed Maste <emaste@freebsd.org>, "Pedro F. Giffuni" <pfg@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-stable@freebsd.org" <svn-src-stable@freebsd.org>, "svn-src-stable-10@freebsd.org" <svn-src-stable-10@freebsd.org> Subject: Re: svn commit: r314937 - in stable/10/sys: fs/ext2fs modules/ext2fs Message-ID: <20170428081746.H4303@besplex.bde.org> In-Reply-To: <20170427221030.GL56922@FreeBSD.org> References: <201703090247.v292l1Ws098712@repo.freebsd.org> <CAPyFy2COF-1Zaz-UfWe6y=oqP0VAYeDZGfLrPzJ0p8_hj7qVfA@mail.gmail.com> <CAGHfRMAz6ZcJw5GwURx3wvUUUV_pCKEoAu6%2B93JmqzqTJWqNTQ@mail.gmail.com> <20170427221030.GL56922@FreeBSD.org>
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On Thu, 27 Apr 2017, Gleb Smirnoff wrote: > On Thu, Apr 27, 2017 at 03:00:56PM -0700, Ngie Cooper wrote: > N> On Thu, Apr 27, 2017 at 1:52 PM, Ed Maste <emaste@freebsd.org> wrote: > N> > On 8 March 2017 at 21:47, Pedro F. Giffuni <pfg@freebsd.org> wrote: > N> >> Author: pfg > N> >> Date: Thu Mar 9 02:47:01 2017 > N> >> New Revision: 314937 > N> >> URL: https://svnweb.freebsd.org/changeset/base/314937 > N> >> > N> >> Log: > N> >> Revert 294545: > N> >> Bringing back ext4: add support for reading sparse files > N> > > N> > Tinderbox is broken on GCC architectures, e.g. from powerpc.LINT64: > N> > > N> > In file included from /scratch/tmp/emaste/freebsd/sys/fs/ext2fs/inode.h:46, > N> > from /scratch/tmp/emaste/freebsd/sys/fs/ext2fs/ext2_alloc.c:50: > N> > /scratch/tmp/emaste/freebsd/sys/fs/ext2fs/ext2_extents.h:91: warning: > N> > declaration does not declare anything > N> > N> ... because of anonymous unions not being supported in gcc 4.2.1. Anonymous unions have been a standard gcc feature since nearly gcc-1. > The whole kernel is built with option that enables them on 4.2.1. > > CFLAGS.gcc+= -fms-extensions This is a bad way to enable standard gcc anonymous unions. It also enables ms extensions which also gives unused extensions of standard gcc anonymous, and other even more unwanted ms features. The correct way to enable gcc features is to compile with -std=gnu99. This has been done for a long time in userland, but the has been misconfigured to use -std=c99 for a long time. This is sort of backwards -- the kernel is inherently more unportable and can't possible be compiled by a C99 compiler, while parts of userland can. However, userland is larger, so people setting excessive -std flags soon found that -std=c99 doesn't work. With no -std flag, gcc defaults to something like -std=gnu89, so it supports its old anonymous unions feature but not the many C99 features needed to compile almost anything now. Bruce
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