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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: bart again (UCX64)
Date: Mon, 04 Sep 2023 18:15:47 -0700
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Xref: csiph.com comp.lang.c:173931

Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:

> David Brown <david.brown@hesbynett.no> writes:
>
>> On 04/09/2023 12:06, Bart wrote:
>
> [...]
>
>>>   char* fred(void) {
>>>   (long long int)rand()*3.14159;
>>>   }
>>>   int main(void) {
>>>   printf("%s\n", fred());
>>>   }
>
> [...]
>
>> As you know, it is not valid C code.  As you know, proper C compilers
>> will - at least - warn you about it when asked to treat the input
>> according to the C standards.  As you know, there isn't a compiler in
>> the world for any language which will stop programmers from writing
>> incorrect code.
>
> Given the context of the discussion, pedantry seems appropriate.
>
> It's invalid C code because it doesn't declare rand() and printf(),
> correctable by adding `#include <stdlib.h>` and `#include <stdio.h>`.
> (It also contains NO-BREAK SPACE characters, but that's that's just a
> Usenet formatting issue.)
>
> Other than that, a conforming C compiler is not required to diagnose
> the above code.  It does have undefined behavior, and a C compiler is
> likely to warn about it with appropriate warnings, but it does not
> violate any syntax rule or constraint.

I say it does.