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From: Bart <bc@freeuk.com>
Newsgroups: comp.lang.c
Subject: Re: question about linker
Date: Fri, 29 Nov 2024 00:32:52 +0000
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On 28/11/2024 23:20, Keith Thompson wrote:
> Bart <bc@freeuk.com> writes:
>> On 28/11/2024 22:38, Keith Thompson wrote:

>>>>     T x;           // defines a readonly variable (which probably needs
>>>>                    // initialising)
>>>>     T* y;          // defines a variable pointer
>>>>
>>>> 'const' is out of the picture.
>>> You say T is an alias (what, a macro?) for 'const int', you show code
>>> using T, and then you say "'const' is out of the picture".  If you
>>> have a point, it escapes me.
>>
>> Well, can you see 'const' in my example? You can't tell x is readonly
>> by only looking at this.
> 
> Yes, you said that T is an alias for 'const int'.  Not sure why you
> wrote "alias".  Is it a macro, or a typedef, or something else?
> 
> I suggest that hiding "const" behind a macro or typedef is usually a bad
> idea.  Why did you do it here?  Is your example based on real code, or
> did you contrive it to be as confusing as possible?

It's to illustrate that the constness of a variable may depend on 
something which is remote from its declaration.

Which is unlike how it usually works elsewhere.

(And if it matters, the alias used a typedef.)

For extra confusion, consider this version:

   T x, *y;

The storage for x is read-only; for y it isn't. Or is it the other way 
around?