Re: Casting the return value of ...

Kaz Kylheku <433-929-6894@kylheku.com> writes:

On 2024-03-28, Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:

The warnings I get from gcc are:
>
warning: ISO C forbids conversion of function pointer to object pointer type [-Wpedantic]
warning: ISO C forbids conversion of object pointer to function pointer type [-Wpedantic]
>
With -pedantic-errors, these become fatal errors.
>
I disagree with gcc.  ISO C doesn't define the behavior, but it doesn't
forbid the conversion.

>
It's never good for a diagnostic to be stating a blatant falsehood,
regardless of whether the presence of the diagnostic is a good idea
or not.

[...]

I'm actually opening a GCC bugzilla about this right now.

I should have remembered that I reported this as a bug in 2017:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83584

That bug report was closed (inappropriately IMHO) as a duplicate of

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=11234

A commenter on bug #83584 cites the C99 Rationale:
"Even with an explicit cast, it is invalid to convert a function pointer
to an object pointer or a pointer to void, or vice versa."

It's not clear what "invalid" means in that context, and in any case the
Rationale is not normative.

N1570 Annex J 5.7 mentions casting between object pointers and function
pointers as a common extension.

Kaz, I see you've submitted
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114526
which has (inappropriately IMHO) been closed as a duplicate of #11234.

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Medtronic
void Void(void) { Void(); } /* The recursive call of the void */