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From: "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: No warning at implicit removal of const. Was: relearning C: why
 does an in-place change to a char* segfault?
Date: Sun, 4 Aug 2024 19:37:11 -0700
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On 8/4/2024 6:06 PM, Ben Bacarisse wrote:
> "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> writes:
> 
>> On 8/2/2024 3:29 PM, Ben Bacarisse wrote:
>>> "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> writes:
>>>
>>>> For some reason I had a sort of a habit wrt const pointers:
>>>>
>>>> (experimental code, no ads, raw text...)
>>>> https://pastebin.com/raw/f52a443b1
>>>>
>>>> ________________________________
>>>> /* Interfaces
>>>> ____________________________________________________________________*/
>>>> #include <stddef.h>
>>>>
>>>>
>>>> struct object_prv_vtable {
>>>>     int (*fp_destroy) (void* const);
>>>> };
>>>>
>>>>
>>>> struct device_prv_vtable {
>>>>     int (*fp_read) (void* const, void*, size_t);
>>>>     int (*fp_write) (void* const, void const*, size_t);
>>>> };
>>> Why?  It seems like an arbitrary choice to const qualify some pointer
>>> types and some pointed-to types (but never both).
>>
>> I just wanted to get the point across that the first parameter, aka, akin
>> to "this" in C++ is a const pointer. Shall not be modified in any way shape
>> or form. It is as it is, so to speak:
>>
>> void foo(struct foobar const* const self);
>>
>> constant pointer to a constant foobar, fair enough?
> 
> No.  If you intended a const pointer to const object why didn't you
> write that?  My point was that the consts seems to be scattered about
> without any apparent logic and you've not explained why.
> 
>>>> ;^)
>>> Does the wink mean I should not take what you write seriously?  If so,
>>> please ignore my question.
>>
>> The wink was meant to show my habit in basically a jestful sort of
>> way.
> 
> Your habit of what?
> 

To write the declaration with names and the const access I want, so:

extern void (void const* const ptr);

void (void const* const ptr)
{
    // ptr is a const pointer to a const void
}