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From: David Brown <david.brown@hesbynett.no>
Newsgroups: comp.lang.c
Subject: Re: question about linker
Date: Sun, 1 Dec 2024 19:33:08 +0100
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On 01/12/2024 17:57, Michael S wrote:
> On Sun, 1 Dec 2024 15:34:04 +0100
> David Brown <david.brown@hesbynett.no> wrote:
>>
>> I can see some advantages in a language being happy with any order of
>> function definition, without requiring forward declarations to use a
>> function before it is defined.  But C is not like that, and I cannot
>> honestly say it bothers me one way or the other.  And apparently, it
>> does not particularly bother many people - there is, I think, no
>> serious impediment or backwards compatibility issue that would
>> prevent C being changed in this way.  Yet no one has felt the need
>> for it - at least not strongly enough to fight for it going in the
>> standard or being a common compiler extension.
>>
>>
>>
> 
> I think, arguing in favor of such change would be easier on top of
> the changes made in C23.
> Before C23 there were, as you put it "no serious impediment or
> backwards compatibility issue". After C23 we could more categorical
> claim that there are no new issues.
> 

Does that mean there was something that you think was allowed in C 
before C23, but not after C23, that would potentially be a problem here?

What, specifically, are you thinking of?

The changes in declarations in C23, AFAIK, are that "void foo();" now 
means the same as "void foo(void);", and that in general non-prototype 
function declarations are no longer allowed.  (That is a good change, of 
course - 30 years late, but still welcome.)  But I can't think of a 
situation where code that is correct under the current "declare before 
using" rule would no longer be correct if "declare before or after" were 
allowed at the file-scope level.

Maybe you could construct something by playing silly-buggers with macros 
to re-define identifiers at different points in the code.

I can't say I've thought much about the consequences of such a rule 
change - it doesn't seem a realistic change to me, and I have no problem 
with the current rule.  So it's quite possible that I've missed something.