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Re: Constants and undefined behavior

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  Re: Constants and undefined behavior Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-08-15 07:58 -0700
    Re: Constants and undefined behavior cross@spitfire.i.gajendra.net (Dan Cross) - 2026-08-18 20:28 +0000

#401211 — Re: Constants and undefined behavior

cross@spitfire.i.gajendra.net (Dan Cross) writes:

> In article <86ldcm82ql.fsf@linuxsc.com>,
> Tim Rentsch  <tr.17687@z991.linuxsc.com> wrote:
>
>> cross@spitfire.i.gajendra.net (Dan Cross) writes:
>>
>>> In article <86tsrc8d0b.fsf@linuxsc.com>,
>>> Tim Rentsch  <tr.17687@z991.linuxsc.com> wrote:
>>> [...]
>>>
>>>> The C standard doesn't need to say that, for example, a
>>>> function x() other than main(), whose name is never referenced,
>>>> will never be called.  If someone wants to establish that x() could
>>>> be called, there needs to be a chain of reasoning going through the
>>>> semantic descriptions given in the C standard, to show that a call
>>>> to x() could occur.
>>>
>>> Actually, no, a reference to a function is not necessary.  A
>>> couple of years ago, a well-publicized issue in a C++ compiler a
>>> couple of years ago was something along the lines of this:
>>> [...]
>>
>> This is comp.lang.c.  My comments were only about C, and not
>> about C++.  But of course you already knew that.
>
> I see you did not read the other messages in the (sub)thread,
> but ok, here it is again, in C:
>
> ```
> term% cat what.c
> #include <stdio.h>
> int main(void) { for (unsigned int k = 0; k != 1; k += 2); return 0; }
> void hello(void) { printf("Hello, World!\n"); }
> term% clang --version | sed 1q
> clang version 22.1.6
> term% clang -Wall -pedantic -pedantic-errors -O1 -std=c23 -o what what.c
> what.c:2:58: warning: for loop has empty body [-Wempty-body]
>   2 | int main(void) { for (unsigned int k = 0; k != 1; k += 2); return 0; }
>     |                                                          ^
> what.c:2:58: note:  put the semicolon on a separate line to silence [...]
> 1 warning generated.
> term% ./what
> Hello, World!
> term%
> ```

This is a childish argument.

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#401308

In article <8633wf5t30.fsf@linuxsc.com>,
Tim Rentsch  <tr.17687@z991.linuxsc.com> wrote:
>cross@spitfire.i.gajendra.net (Dan Cross) writes:
>
>> In article <86ldcm82ql.fsf@linuxsc.com>,
>> Tim Rentsch  <tr.17687@z991.linuxsc.com> wrote:
>>
>>> cross@spitfire.i.gajendra.net (Dan Cross) writes:
>>>
>>>> In article <86tsrc8d0b.fsf@linuxsc.com>,
>>>> Tim Rentsch  <tr.17687@z991.linuxsc.com> wrote:
>>>> [...]
>>>>
>>>>> The C standard doesn't need to say that, for example, a
>>>>> function x() other than main(), whose name is never referenced,
>>>>> will never be called.  If someone wants to establish that x() could
>>>>> be called, there needs to be a chain of reasoning going through the
>>>>> semantic descriptions given in the C standard, to show that a call
>>>>> to x() could occur.
>>>>
>>>> Actually, no, a reference to a function is not necessary.  A
>>>> couple of years ago, a well-publicized issue in a C++ compiler a
>>>> couple of years ago was something along the lines of this:
>>>> [...]
>>>
>>> This is comp.lang.c.  My comments were only about C, and not
>>> about C++.  But of course you already knew that.
>>
>> I see you did not read the other messages in the (sub)thread,
>> but ok, here it is again, in C:
>>
>> ```
>> term% cat what.c
>> #include <stdio.h>
>> int main(void) { for (unsigned int k = 0; k != 1; k += 2); return 0; }
>> void hello(void) { printf("Hello, World!\n"); }
>> term% clang --version | sed 1q
>> clang version 22.1.6
>> term% clang -Wall -pedantic -pedantic-errors -O1 -std=c23 -o what what.c
>> what.c:2:58: warning: for loop has empty body [-Wempty-body]
>>   2 | int main(void) { for (unsigned int k = 0; k != 1; k += 2); return 0; }
>>     |                                                          ^
>> what.c:2:58: note:  put the semicolon on a separate line to silence [...]
>> 1 warning generated.
>> term% ./what
>> Hello, World!
>> term%
>> ```
>
>This is a childish argument.

Well, your response certainly is.

	- Dan C.

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