A: a new bug to old plain C

Tue Nov 25 10:24:11 GMT 2025

We're not converting "Foo** -> const Foo**". We are doing "Foo** -> const
Foo * const * const" conversion and this works fine (according to the right
the same
https://isocpp.org/wiki/faq/const-correctness#constptrptr-conversion which
was mentioned).

So, what we're doing is correct from both language syntax and coding
practices (safe coding) points of view.
This bug should be reported and fixed!!!

Respectfully,
Aleksandr G Povaliaev.

пн, 24 нояб. 2025 г. в 20:49, Henrik Holst <henrik.holst@millistream.com>:

> no they are not, they are a WIKIfication of the C specification, in
> particular the heading "Why am I getting an error converting a Foo** →
> const Foo**?" in an official FAQ from the C Standards Committee should make
> you realize this.
>
> /HH
>
> Den mån 24 nov. 2025 kl 18:45 skrev Александр Поваляев <
> apovalyaev@gmail.com>:
>
>> The articles mentioned are all about coding practices ("safe" and
>> "unsafe"). They are not about bugs in compilers and hard restrictions being
>> placed on where I can use "const" in my code and where I can't. :)
>>
>> The links mentioned earlier just give a recommendation to use "Foo** ->
>> const Foo * const *" conversion instead of "Foo** -> const Foo**".
>> Literally, what I am saying is that: "if you can use const, you should
>> use it". And this is the case which just confirms my attitude.
>> But again, this is about coding practices and recommendations. There is
>> no place in C and C++ standards saying "DON"T USE CONST EVEN IF YOU CAN DO
>> IT. WE'RE PROHIBITING THIS".
>>
>> And so, what GCC compiler (+ some SDKs) is doing now is just the opposite
>> to the recommendation mentioned. It restricts the places where "const"
>> might be used.
>> Anyway, it is a BUG (BIG BUG!!!) in the GCC + SDK. And the BUG was not
>> made intentionally to protect software engineers from using "unsafe coding
>> practices" :)))))
>> For such kind of practices, there are warnings with information messages.
>> And the bug in GCC should be (1) reported; (2) nailed down and (3) fixed.
>>
>> Respectfully,
>> Aleksandr G Povaliaev.
>>
>>
>> пн, 24 нояб. 2025 г. в 16:10, Henrik Holst <henrik.holst@millistream.com
>> >:
>>
>>>
>>>
>>> Den mån 24 nov. 2025 kl 13:40 skrev Александр Поваляев <
>>> apovalyaev@gmail.com>:
>>>
>>>> Hi there!
>>>>
>>>> "False sense of security". Const is a hint to any C compiler to make
>>>> code more error-prone. So, it is always better to use as much "const" as
>>>> possible.
>>>> My point is that "if const might be used, it SHOULD be used". That is
>>>> the cornerstone.
>>>> I want to use it, so GCC compiler + SDK should make it possible. It is
>>>> my code and my design decisions being undertaken.
>>>>
>>>> All discussions if it is possible to overcome or not "Const"
>>>> restriction is irrelivant here.
>>>>
>>> no it is not irrelevant here because if I declare a variable as const in
>>> my local code the value should not be changed by other code either, look at
>>> the code in the link given to you earlier which shows just such a case as
>>> an example on why this is not allowed in C.
>>>
>>> /HH
>>>
>>>>
>>>> Respectfully,
>>>> Aleksandr G Povaliaev.
>>>>
>>>> пн, 24 нояб. 2025 г. в 13:46, Henrik Holst <
>>>> henrik.holst@millistream.com>:
>>>>
>>>>> The things is that this is unsafe and invalid due to it creating a
>>>>> false sense of security. Aka your "const Foo *" can change under your feet
>>>>> by _other_ code leading to your const here giving you a false sense of
>>>>> security. Yes it prevents you from modifying it locally but not some other
>>>>> code or thread from modifying your const pointer to now point to something
>>>>> else, hence the compiler issues an error here since you do not get what you
>>>>> think you are getting.
>>>>>
>>>>> /HH
>>>>>
>>>>> Den mån 24 nov. 2025 kl 11:10 skrev Александр Поваляев via Gcc-help <
>>>>> gcc-help@gcc.gnu.org>:
>>>>>
>>>>>> Hi there!
>>>>>>
>>>>>> The code is not invalid and neither of the links posted saying that
>>>>>> "const
>>>>>> Foo * const * const" is invalid construction for C.
>>>>>> The links posted just are discussing that it might be UNSAFE to cast
>>>>>> "Foo
>>>>>> **" -> "const Foo **" and recommending usage of "Foo **" -> "const
>>>>>> Foo *
>>>>>> const *" instead.
>>>>>> It's OK. If you feel that it is unsafe, please don't use it. It is
>>>>>> your own
>>>>>> decision.
>>>>>>
>>>>>> But the syntax itself "const Foo * const * const" is correct and the
>>>>>> use-case I mentioned is quite simple and evident.
>>>>>> And so I need this code snipped to be compiled transparently over all
>>>>>> the
>>>>>> GCC (and platform SDKs) available versions.
>>>>>>
>>>>>> Respectfully,
>>>>>> Aleksandr G Povaliaev.
>>>>>>
>>>>>>
>>>>>> пн, 24 нояб. 2025 г. в 01:48, David Brown <david.brown@hesbynett.no>:
>>>>>>
>>>>>> > On 23/11/2025 21:45, Александр Поваляев via Gcc-help wrote:
>>>>>> > > Hi there!
>>>>>> > >
>>>>>> >
>>>>>> > This is getting /extremely/ frustrating.  /Please/ find some way to
>>>>>> > learn the C programming language - courses, books, good online
>>>>>> resources.
>>>>>> >
>>>>>> > And /please/ believe me when I say that people who have worked with
>>>>>> C
>>>>>> > and C++ for decades, studied the standards, who serve on the
>>>>>> standards
>>>>>> > committee, know better about these things than you do.  (I'm talking
>>>>>> > about Jonathan here, not myself - he really is a world-class expert
>>>>>> here.)
>>>>>> >
>>>>>> > > Either the links you've provided or the links you provided earlier
>>>>>> > > (yesterday) are irrelevant, cause they are just discussing if it
>>>>>> is safer
>>>>>> > > to convert "Foo_Type **" to "const Foo_Type **" or not.
>>>>>> > >
>>>>>> >
>>>>>> > The links are highly relevant.  They explain why you cannot convert
>>>>>> from
>>>>>> > "char **" to "const char **".  That also explains why you cannot
>>>>>> convert
>>>>>> > from "char **" to "const char * const * const".  Adding even more
>>>>>> > "const" qualifiers to the invalid conversion does not somehow
>>>>>> magically
>>>>>> > make it work.
>>>>>> >
>>>>>> > > Once again, we are not converting "char** to const char**", we're
>>>>>> > > converting char** to const char * const * const".
>>>>>> > > And we're not discussing if it is safer or not, we are discussing
>>>>>> GCC
>>>>>> > > compiler error.
>>>>>> > >
>>>>>> >
>>>>>> > The compiler is generating an error message because you wrote
>>>>>> invalid
>>>>>> > code.  The error - or bug, if you like - is in /your/ code.  Not the
>>>>>> > compiler.  GCC is doing its job correctly here.
>>>>>> >
>>>>>> > >
>>>>>> > > Respectfully,
>>>>>> > > Aleksandr G Povaliaev.
>>>>>> > >
>>>>>> >
>>>>>> > I'm sorry, but signing the post with "respectfully" does not make it
>>>>>> > respectful.  You started the thread disrespectfully - insisting that
>>>>>> > there is a bug in GCC when you simply do not understand the relevant
>>>>>> > aspects of the C programming language.  And you have gone downhill
>>>>>> since
>>>>>> > then, ignoring and rejecting the help and advice you have been
>>>>>> given.
>>>>>> > Getting things wrong once is entirely understandable - this is a
>>>>>> subtle
>>>>>> > point of the C language, and you are posting to a "help" list.
>>>>>> Doubling
>>>>>> > down on your ignorance when you have received the help and
>>>>>> information
>>>>>> > you need, is a different matter entirely.
>>>>>> >
>>>>>> > Your code is flawed.  You need to fix it.  Mindlessly repeating your
>>>>>> > misunderstandings about how you think C works will not do anything
>>>>>> but
>>>>>> > annoy people.
>>>>>> >
>>>>>> > David
>>>>>> >
>>>>>> >
>>>>>>
>>>>>