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Date:      Sat, 30 Jun 2018 10:19:22 -0700
From:      Mark Millard <marklmi@yahoo.com>
To:        John Baldwin <jhb@FreeBSD.org>, Dimitry Andric <dim@FreeBSD.org>
Cc:        Bryan Drewery <bdrewery@FreeBSD.org>, svn-src-head@freebsd.org, FreeBSD Current <freebsd-current@freebsd.org>
Subject:   Re: head -r335782 (?) broke ci.freebsd.org's FreeBSD-head-amd64-gcc build (lib32 part of build)
Message-ID:  <F60AE252-CB8E-429E-97BF-812CC4012A90@yahoo.com>
In-Reply-To: <49BF6569-96A9-4104-BDE6-8BB94C0D9626@yahoo.com>
References:  <00D1127A-1F0E-4E0E-B86C-1C5AA5B2E085@yahoo.com> <CF0230A1-1384-4F0F-A96A-5AB555FD17AC@yahoo.com> <7A845F2C-C994-4828-823D-33A97B7B6EB0@yahoo.com> <72081b02-cf23-82ec-32df-7f5793c35f57@FreeBSD.org> <003509F0-F2F4-4A43-82FE-3F6FC23D19D4@yahoo.com> <65b19cc4-eaf0-13ed-43e6-9f04a1f7f196@FreeBSD.org> <FF369ACC-D496-49AF-BB41-406936E433B0@yahoo.com> <edcd2126-3554-f444-6ba0-3da94d887dfe@FreeBSD.org> <49BF6569-96A9-4104-BDE6-8BB94C0D9626@yahoo.com>

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On 2018-Jun-30, at 10:04 AM, Mark Millard <marklmi at yahoo.com> wrote:

> On 2018-Jun-30, at 9:29 AM, John Baldwin <jhb at FreeBSD.org> wrote:
>=20
>> On 6/30/18 9:17 AM, Mark Millard wrote:
>>> On 2018-Jun-30, at 7:51 AM, John Baldwin <jhb at FreeBSD.org> wrote:
>>>=20
>>>> On 6/29/18 2:37 PM, Mark Millard wrote:
>>>>> [I expect this is more than just amd64-gcc related but that is all
>>>>> that ci.freebsd.org normally builds via a devel/*-gcc .]
>>>>=20
>>>> As indicated by my other mail, this is i386 and amd64 specific as =
it
>>>> only matters for float.h on i386 due to the disagreement on
>>>> LDBL_MANT_DIG.
>>>=20
>>> I was correct about the search order for include files being
>>> different before -r335782 vs. -r335782 and later:
>>=20
>> Yes, but this is kind of a feature, not a bug, and the issue there is =
that
>> as much as possible we should allow FreeBSD to work with the standard =
headers
>> that are supposed to be part of the language (and thus provided by =
the
>> toolchain).  Right now we don't ship any of the 'std*.h' headers =
clang
>> provides for example in our base system clang, though a few months =
ago I
>> fixed the one place that was using <machine/stdarg.h> instead of
>> <stdarg.h> in userland that was breaking the use of the =
toolchain-provided
>> stdarg.h (both GCC and clang).
>>=20
>>> Might this reversal have other effects even for
>>> architectures for which the code does compile
>>> via devel/*-gcc ?
>>=20
>> It depends on the header.  This particular failure is due to a quirk =
of
>> <float.h> on FreeBSD/i386.  I have built other platforms with =
external
>> GCC just fine.  To the extent that we encounter any other issues we
>> should try to make our source more conformant with C and only fall =
back to
>> axeing the toolchain-provided language headers as a last resort.
>=20
> It is too bad that the review https://reviews.freebsd.org/D16055 did =
not
> catch the change in what headers are used by buildworld and =
buildkernel.
> I'd view such switching of long established header bindings as a
> fairly big deal, possibly even warranting being explicitly proposed =
and
> debated.
>=20
> I'm not claiming my opinion on which search order that I have is
> actually relevant. I'm just now nervous about my powerpc64-gcc based
> builds having unexpected differences, for example. [I sometimes =
explore
> the status of powerpc family builds via more modern toolchains.]
>=20
> (But lib32 for powerpc64 via modern gcc's is messed up anyway,
> generating code in crtbeginS.o for the wrong ABI: using R30 =
incorrectly.
> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D206123 has more =
about
> that.)

Looks like my being nervous is justified: there is a conflicting =
altivec.h
that has nothing to do with C/C++ language standards:

# ls /usr/local/lib/gcc/powerpc64-unknown-freebsd12.0/6.4.0/include/
altivec.h		htmxlintrin.h		ppc-asm.h		=
spe.h			stdarg.h		stddef.h		=
stdint.h		varargs.h
float.h			iso646.h		ppu_intrinsics.h	=
spu2vmx.h		stdatomic.h		stdfix.h		=
stdnoreturn.h		vec_types.h
htmintrin.h		paired.h		si2vmx.h		=
stdalign.h		stdbool.h		stdint-gcc.h		=
tgmath.h

I've not checked for other name conflicts vs. FreeBSD. I just happen
to recognize altivec.h . There is:

=
/usr/obj/powerpc64vtsc_xtoolchain-gcc/powerpc.powerpc64/usr/src/powerpc.po=
werpc64/tmp/usr/include/machine/altivec.h

=
/usr/obj/powerpc64vtsc_xtoolchain-gcc/powerpc.powerpc64/usr/src/powerpc.po=
werpc64/tmp/usr/lib/clang/6.0.0/include/altivec.h

=
/usr/obj/powerpc64vtsc_xtoolchain-gcc/powerpc.powerpc64/usr/src/powerpc.po=
werpc64/obj-lib32/tmp/usr/include/machine/altivec.h



=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)




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