[llvm-dev] RFC: On removing magic numbers assuming 8-bit bytes

via llvm-dev llvm-dev at lists.llvm.org
Thu May 2 10:31:40 PDT 2019

I don't think it was really that severe of a "subset" and would
dispute that a "subset" is inherently "incompatible" but that
is straying too far from the topic at hand to tolerate.

> -----Original Message-----
> From: jfbastien at apple.com [mailto:jfbastien at apple.com]
> Sent: Thursday, May 02, 2019 1:25 PM
> To: Robinson, Paul
> Cc: jesper.antonsson at ericsson.com; llvm-dev at lists.llvm.org
> Subject: Re: [llvm-dev] RFC: On removing magic numbers assuming 8-bit
> bytes
> > On May 2, 2019, at 10:21 AM, paul.robinson at sony.com wrote:
> >
> >> -----Original Message-----
> >> From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of JF
> >> Bastien via llvm-dev
> >>
> >> I’m not a fan of C and C++ supporting anything but 8 bits per byte.
> >> Realistically, C and C++ on such targets are different languages from
> 8-
> >> bit-per-byte C and C++, and therefore code isn’t portable from one to
> the
> >> other.
> >
> > Having done it, I promise you that it's reasonable to write portable C
> > targeting both 7-bit and 8-bit 'char'.  It was too long ago to remember
> > anything in detail, but the brain cells still remaining from that era
> > believe it was pretty clean.
> I agree it’s *possible*, same way I’ve seen some correct uses of volatile,
> and the same way I’m sure some code supported non-two’s-complement
> machines correctly. What I’m saying is that most code simply isn’t, often
> in subtle ways. The code you wrote is therefore a subset of C which is
> incompatible with C at large.
> >> I intend to propose that C++23 support only 8 bits per byte, ditto
> >> C. I’m therefore not a fan of teaching clang about this.
> >
> > My impression is that non-8-bit-byte machines are (these days) generally
> > small and likely for embedded or other special purposes, so a proposal
> > to stop trying to squeeze the bloated monster that C++ has become onto
> > those is probably fine. C, on the other hand, appears to be the language
> > of choice for all sorts of weird things, and that's less likely to fly.
> > (Just sayin'. I'm not on either committee and have no vested interest.)
> > --paulr
> >

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