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Date:      Thu, 9 Aug 2018 19:44:52 -0700
From:      Conrad Meyer <cem@freebsd.org>
To:        Benjamin Kaduk <bjkfbsd@gmail.com>
Cc:        "cem@FreeBSD.org" <cem@freebsd.org>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org,  svn-src-head@freebsd.org
Subject:   Re: svn commit: r337535 - head/sbin/init
Message-ID:  <CAG6CVpVyaug5uf5SpmMaA0UyciBZd8qP8FyDj5Sgb5MyxLvgjQ@mail.gmail.com>
In-Reply-To: <CAJ5_RoC5s-oVrkPx%2BCcF5oRhzqYniGcaF6hEZN7oFLonrV7Vfw@mail.gmail.com>
References:  <201808091217.w79CH3gO096411@repo.freebsd.org> <CAJ5_RoBVWZgMgoNGkTkCMB9kU5Ci1GcN-p_Ad-FMMwhO%2BQX5VA@mail.gmail.com> <CAG6CVpU8jwQJiNsf6B5Gq75QHEoGaT4K-dCK6Drc59ETPH4VRw@mail.gmail.com> <CAJ5_RoC5s-oVrkPx%2BCcF5oRhzqYniGcaF6hEZN7oFLonrV7Vfw@mail.gmail.com>

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Then maybe don=E2=80=99t keep bringing it up? Especially when it=E2=80=99s =
totally
irrelevant, like here.  FreeBSD has certain assumptions of supported
platforms beyond the guarantees of standard C that have nothing whatsoever
to do with the boogeyman of a patched compiler.

On Thu, Aug 9, 2018 at 2:42 PM Benjamin Kaduk <bjkfbsd@gmail.com> wrote:

> On Thu, Aug 9, 2018 at 11:03 AM, Conrad Meyer <cem@freebsd.org> wrote:
>
>> On Thu, Aug 9, 2018 at 5:52 AM, Benjamin Kaduk <bjkfbsd@gmail.com> wrote=
:
>> > On Thu, Aug 9, 2018 at 7:17 AM, Edward Tomasz Napierala <
>> trasz@freebsd.org>
>> > wrote:
>> >>   Use NULLs instead of casted zeroes, for consistency.
>> >
>> > It's probably helpful to note explicitly that these are not in
>> arguments to
>> > varargs functions,
>>
>> I don't think it's helpful.
>>
>> > in which case the explicit cast is needed in order to produce a progra=
m
>> that
>> > will have
>> > correct behavior on all compliant compilers/systems.
>>
>> Here "compliant" means "minimally compliant to the C standard."  Use
>> of NULL in varargs is functionally correct on all FreeBSD systems.
>>
>> >  (We do define NULL to
>> > be a zero-with-cast,
>> > but programs
>>
>> (Ones that care about portability to weird systems.)  I don't think
>> BSD's 500 line init =E2=80=94 hyper local to FreeBSD =E2=80=94 is a stro=
ng candidate
>> for portability.
>>
>> > should not assume that NULL will be of pointer type -- "An
>> > integer constant
>> > expression with the value 0, or such an expression cast to type void *=
,
>> is
>> > called a null pointer constant".)
>>
>> Right.  The problem only arises when both conditions are met:
>>
>> 1. The system's varargs representation is smaller than the pointer
>> representation, and
>> 2. The runtime headers do not defined NULL as a pointer-typed value.
>> (3. The function being invoked is actually varargs?)
>>
>> Neither is true on FreeBSD and v7-style init is not a useful place to
>> call for portability.
>>
>
> I don't really feel a need to continue the discussion that was already
> started in response
> to  r336835 (in addition to the current thread), so I'll limit myself to
> asking whether we
> want to be writing standard C or a FreeBSD-specific dialect of C.  My
> understanding was
> that we had some experience with the latter (e.g., heavy patching of the
> compiler) and
> it ended up with us in a bad place, which would tend to support writing
> standard C or
> as close to it as we can.  (Yes, I know that we have non-standard printf
> specifiers and the like.)
>
> -Ben
>



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