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Date:      Wed, 21 Aug 2019 09:01:48 -0700
From:      Marshall Clow <mclow.lists@gmail.com>
To:        =?UTF-8?Q?T=C4=B3l_Coosemans?= <tijl@freebsd.org>
Cc:        Dimitry Andric <dim@freebsd.org>, src-committers <src-committers@freebsd.org>,  svn-src-all <svn-src-all@freebsd.org>, svn-src-head@freebsd.org
Subject:   Re: svn commit: r351253 - in head/contrib/libc++: include src
Message-ID:  <CAMBqOshqSZ1t6dMXnGzUvHzixFXJMnw4TjbkChUmRdN0V_O2Eg@mail.gmail.com>
In-Reply-To: <20190821151949.00c9845c@FreeBSD.org>
References:  <201908201739.x7KHdXvv054610@repo.freebsd.org> <20190821144908.7137e6bc@FreeBSD.org> <F6455A96-9AB3-428B-A486-981C313FCD39@FreeBSD.org> <20190821151949.00c9845c@FreeBSD.org>

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On Wed, Aug 21, 2019 at 6:20 AM T=C4=B3l Coosemans <tijl@freebsd.org> wrote=
:

> On Wed, 21 Aug 2019 15:07:56 +0200 Dimitry Andric <dim@FreeBSD.org>
> wrote:
> > On 21 Aug 2019, at 14:49, T=C4=B3l Coosemans <tijl@FreeBSD.org> wrote:
> >> On Tue, 20 Aug 2019 17:39:33 +0000 (UTC) Dimitry Andric
> >> <dim@FreeBSD.org> wrote:
> >>> Author: dim
> >>> Date: Tue Aug 20 17:39:32 2019
> >>> New Revision: 351253
> >>> URL: https://svnweb.freebsd.org/changeset/base/351253
> >>>
> >>> Log:
> >>>  Pull in r368867 from upstream libc++ trunk (by Marshall Clow):
> >>>
> >>>    Rework recursive_timed_mutex so that it uses __thread_id instead o=
f
> >>>    using the lower-level __libcpp_thread_id. This is prep for fixing
> >>>    PR42918. Reviewed as https://reviews.llvm.org/D65895
> >>>
> >>>  Pull in r368916 from upstream libc++ trunk (by Marshall Clow):
> >>>
> >>>    Fix thread comparison by making sure we never pass our special 'no=
t
> a
> >>>    thread' value to the underlying implementation. Fixes PR#42918.
> >>>
> >>>  This should fix std::thread::id::operator=3D=3D() attempting to call
> >>>  pthread_equal(3) with zero values.
> > ...
> >> This seems to break building Firefox:
> >>
> >> In file included from
> /usr/ports/www/firefox/work/firefox-68.0.2/media/mtransport/nricectx.cpp:=
82:
> >> In file included from
> /usr/ports/www/firefox/work/firefox-68.0.2/media/mtransport/third_party/n=
ICEr/src/stun/stun_client_ctx.h:41:
> >> In file included from
> /usr/ports/www/firefox/work/firefox-68.0.2/media/mtransport/third_party/n=
ICEr/src/stun/stun.h:45:
> >> In file included from /usr/include/net/if_var.h:84:
> >> /usr/include/sys/lock.h:68:15: error: reference to 'thread' is ambiguo=
us
> >>                            struct thread **owner);
> >>                                   ^
> >> /usr/include/sys/lock.h:42:8: note: candidate found by name lookup is
> 'thread'
> >> struct thread;
> >>       ^
> >> /usr/include/c++/v1/__threading_support:397:24: note: candidate found
> by name
> >>      lookup is 'std::__1::thread'
> >> class _LIBCPP_TYPE_VIS thread;
> >>                       ^
> >>
> >> This "class thread" conflicts with "struct thread" in sys/lock.h.
> >> Should everything in sys/lock.h be under #ifdef _KERNEL?
> >
> > Maybe, but is Firefox using "using namespace std;" here?  It is a likel=
y
> > explanation for the ambiguity between the global struct thread from
> > sys/lock.h, and std::thread from libc++.
>
> Yes, several headers in media/mtransport/third_party/nICEr/src start
> with:
>
> #ifdef __cplusplus
> using namespace std;
> extern "C" {
> #endif /* __cplusplus */
>

libc++ has always had a `std::thread` struct.

The change here is that forward declaration moved from <thread> to
<__threading_support>, and
that was included by <mutex>.

-- Marshall



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