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From: Dan Cross <crossd@gmail.com>
To: Steve Nickolas <usotsuki@buric.co>
Cc: TUHS <tuhs@tuhs.org>
Subject: [TUHS] Re: [TUHS]: C dialects (was: I can't drive 55: "GOTO considered harmful" 55th anniversary)
Date: Mon, 13 Mar 2023 16:26:54 -0400	[thread overview]
Message-ID: <CAEoi9W6D0gnTYA7AWtQP5CFovMsPhz0O+PeRrcyebjGOsDLESw@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.21.2303131512140.3310@sd-119843.dedibox.fr>

On Mon, Mar 13, 2023 at 3:16 PM Steve Nickolas <usotsuki@buric.co> wrote:
> On Mon, 13 Mar 2023, Clem Cole wrote:
> > Frankly, I'd probably rather see ISO drop a bunch of the stuff they are now
> > requiring and fall back at least to K&R2 -- keep it simple. The truth is
> > that we still use the language today is that K&R2 C was then (and still is)
> > good enough and got (gets) the job done extremely well.    Overall, I'm not
> > sure all the new "features" have added all that much.
>
> C99 did introduce one thing I use: <stdint.h>
>
> Beyond that, I still code strict C89.  I simply treat the language itself
> as ossified.  I also still make assumptions about the compiler that might
> not still be true, so for example
>
>   unsigned short a;
>   unsigned char b;
>
>   b=0xFF;
>   a=b<<8;
>
> I expect to return 0 even though the logical answer is 0xFF00,

I don't know why one would expect that. `b` will be promoted to
(signed!!) `int` before the shift, and then the result of that
assigned to `a`, wrapping as needed to fit into the `unsigned short`;
on most reasonable systems the UB gods won't be angered.

OTOH, `uint16_t mul(uint16_t a, uint16_t b) { return a * b; }` is a UB
minefield on most systems.

> and I
> _always_ code it like this:
>
>   b=0xFF;
>   a=b;
>   a<<=8;

Curiously, this will be subject to the same type promotion rules as
the original.

> or alternatively
>
>   b=0xFF;
>   a=((unsigned short) b)<<8;

As will this. In fact, the cast here is completely superfluous; the
shift will still be done using after promotion to signed int.

> and there's other defensive stuff I do.  I honestly don't see the point in
> the other changes to the language and feel they take C away from what it
> has always been.

I think an issue is that there is what people _think_ C does, and what
C _actually_ does, and the two are often discordant; this is why I
think you see people tweaking compiler options to create a dialect
that's reasonable to program in: given a large-enough code base, you
inevitably end up with a very peculiar dialect, which compounds the
problem. For example, I'm quite sure that the C dialect that Linux
uses is not the same as the C that Windows uses, and so on. The
compiler writers now seem very much of the mind where you point this
out and they look at you and say, "tough."

        - Dan C.

  reply	other threads:[~2023-03-13 20:27 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-10 11:37 [TUHS] Re: I can't drive 55: "GOTO considered harmful" 55th anniversary Noel Chiappa
2023-03-10 11:51 ` [TUHS] Conditions, AKA exceptions. (Was: I can't drive 55: "GOTO considered harmful" 55th anniversary) Ralph Corderoy
2023-03-10 15:54 ` [TUHS] Re: I can't drive 55: "GOTO considered harmful" 55th anniversary Dan Cross
2023-03-12  7:39   ` Anthony Martin
2023-03-12 11:40     ` Dan Cross
2023-03-12 16:40       ` Paul Winalski
2023-03-13  3:25       ` John Cowan
2023-03-13 10:40         ` Alejandro Colomar (man-pages)
2023-03-13 12:19           ` Dan Cross
2023-03-13 12:43             ` [TUHS] [TUHS]: C dialects (was: I can't drive 55: "GOTO considered harmful" 55th anniversary) Alejandro Colomar
2023-03-13 12:46               ` [TUHS] " Dan Cross
2023-03-13 16:00               ` Paul Winalski
2023-03-13 19:00                 ` Clem Cole
2023-03-13 19:09                   ` Larry McVoy
2023-03-13 19:17                   ` Steve Nickolas
2023-03-13 20:26                     ` Dan Cross [this message]
2023-03-13 22:25                       ` Alejandro Colomar (man-pages)
2023-03-13 19:24                   ` [TUHS] Re: [TUHS]: C dialects Luther Johnson
2023-03-13 19:38                     ` Luther Johnson
2023-03-14 19:48                     ` John Cowan
2023-03-14 19:56                       ` Joseph Holsten
2023-03-14 20:01                       ` Luther Johnson
2023-03-13 20:48                   ` [TUHS] Re: [TUHS]: C dialects (was: I can't drive 55: "GOTO considered harmful" 55th anniversary) Paul Winalski
2023-03-13 20:56                     ` Bakul Shah
2023-03-14  1:06                     ` Larry McVoy
2023-03-13 21:00                   ` Paul Winalski
2023-03-13 21:07                     ` Bakul Shah
2023-03-13 21:14                       ` Dan Cross
2023-03-13 22:15                         ` Dave Horsfall
2023-03-13 22:47                           ` Dave Horsfall
2023-03-14  0:23                             ` Dan Cross
2023-03-14  0:21                           ` Dan Cross
2023-03-14 13:52                             ` Chet Ramey
2023-03-14  1:27                         ` Bakul Shah
2023-03-13 21:28                       ` Paul Winalski
2023-03-14 10:04                       ` [TUHS] C dialects Ralph Corderoy
2023-03-14 20:02                         ` [TUHS] " John Cowan
2023-03-14 21:34                           ` Thomas Paulsen
2023-03-14  0:38                     ` [TUHS] Re: [TUHS]: C dialects (was: I can't drive 55: "GOTO considered harmful" 55th anniversary) John Cowan
2023-03-14  2:49                 ` Theodore Ts'o
2023-03-14  3:06                   ` G. Branden Robinson
2023-03-15  3:59 Noel Chiappa
2023-03-15  4:33 ` John Cowan
2023-03-16 22:50 ` Bakul Shah

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