Re: A: a new bug to old plain C

Hi there!

My reply gives a detailed description why the arguments you provided are
not correct (as for the formal logic). Please try to be more accurate.
We're talking about GCC (as I wrote in my original response to committee),
not C++.

And what I asked for is if С standard explicitly prohibits "Foo**" ->
"const Foo * const * const" conversion.
And I have not received any confirmation of it either from you or from the
other participants of this e-mail thread.

We're talking about the point which was implemented differently by
compilers (see my previous post within the code snippet).
And I am wondering why the things which are not explicitly prohibited by C
standard are interpreted as errors, not warnings.

As for now the bottom line: about 50% of well known C compilers don't
interpret "Foo**" -> "const Foo * const * const" conversion as an error and
there is no explicit prohibition of it by C standard.
Right?

As for "Foo**" -> "void*" -> "const Foo * const * const" conversion
proposal. Yep it will work fine also, without error (see the results below).
But once again, I would prefer not to deviate from the original topic.
Thank you for your participation to this discussion.

void subfunc(struct zzz const * const * const arg) {

if (arg != NULL) {
printf("%s", "Done!");
}
}

void func(struct zzz ** arr_of_ptr, unsigned count) {

subfunc((void*)arr_of_ptr); // CLANG: x86-64 clang (trunk) - OK!
// GCC: x86-64 gcc (trunk) - OK!
// INTEL: x86-64 icc 2021.10.0 - OK!
// MICROSOFT(c++?): x64 msvc v19.latest - OK!
// POWER64 GCC trunk - OK!
// ARM gcc(trunk) - OK!
// NOTE: based on godbolt.org
}

Respectfully,
Aleksandr G Povaliaev.

ср, 26 нояб. 2025 г. в 19:14, LIU Hao <[email protected]>:

> 在 2025-11-26 21:48, Александр Поваляев 写道:
> > I want to emphasize here "One of the following shall hold"!.
> > So, if one of the following is being hold, the conversion/assignment is
> permitted.
>
> > But USE THE SAME TRICK WITH DISJUNCTION AND CONJUNCTION to prove that
> "Foo**" -> const Foo * const *
> > const" is not correct.
> > IT IS WRONG WAY.
> > To be logically correct you need to show that NO ONE OF THE 6.5.17.2
> STATEMENT is TRUE for "Foo**" ->
> > const Foo * const * const" logic.
>
> If you had read the damn standard, you would have known that the others
> are all about arithmetic types,
> structs and unions, pointer to void, and conversion to `bool`, and
> apparently they do not apply. Pity.
>
> Because you are writing C, you don't need to cast the pointer to `struct
> zzz const * const * const`; you
> just cast to `void*`. If you don't know that, you cannot know more C than
> me.
>
> I'm already very disappointed about this thread, because half of the
> messages are about `char **` does
> not implicit convert to `const char **` which is technically a different
> question from yours. And now I'm
> getting more, because of your disrespect.
>
>
> > But it is ok. It is usually being studied at some university courses, so
> if you decide to enter some high
> > education school you will learn all of these things.
>
> You are in no position to say that. We are well educated, and apparently
> you are not such a person.
>
>
> --
> Best regards,
> LIU Hao
>