head -r335782 (?) broke ci.freebsd.org's FreeBSD-head-amd64-gcc build (lib32 part of build)

[Mark Millard]

On 2018-Jun-30, at 9:29 AM, John Baldwin <jhb at FreeBSD.org> wrote:

> 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:
>> 
>>> 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 .]
>>> 
>>> 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.
>> 
>> I was correct about the search order for include files being
>> different before -r335782 vs. -r335782 and later:
> 
> 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).
> 
>> Might this reversal have other effects even for
>> architectures for which the code does compile
>> via devel/*-gcc ?
> 
> 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.

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.

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.]

(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=206123 has more about
that.)

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