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.
C23 will be adding new types that don't have this issue (default promotion to in). If a variable has 3 bits, it will have 3 bits (until you mix it with a wider variable).
Another whole class of Undefined Behavior (in ISO C) or implementation-defined behavior (K&R C) is 2's complement arithmetic which has never been portable, until C23. So it's not all bad.
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;
Indeed. That's my feeling too. When discussing about features that programmers don't understand why they were added, it's rather often the case that the feature has been there for longer than they thought (if not since forever).
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."
Even "safe" Rust is having its share of Undefined Behavior. Let's see how they deal with it.