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Groups > comp.lang.c > #177360

Re: Call to a function

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Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
[...]
> The point isn't quite the same.  The C standard explicitly says
> integers may be converted to any pointer type.  The C standard
> does not say that a pointer to an object type may be converted
> to a pointer to function type.  Every implementation is within
> its rights to reject any program whose static text includes[*] a
> cast from a pointer to an object type to a pointer to function
> type, regardless of whether the cast has any chance of being
> executed.
>
> [*] meaning, still present as source of any preprocessor
> conditionals have been processed, etc.

I disagree.  (I think we've discussed this before.)

Concretely, I believe that this program violates no syntax error or
constraint.  It includes code whose behavior would be undefined if it
were executed, but the `if (0)` prevents that.

On what basis do you think a conforming implementation may reject it?
Do you see a syntax rule or constraint that it violates?  Do you see
some other basis for rejecting it?

int main(void) {
    int obj = 42;
    typedef void func(void);
    if (0) {
        func *fptr = (func*)&obj;
        fptr();
    }
}

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */

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Re: Call to a function Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-22 15:21 +0000
  Re: Call to a function James Kuyper <jameskuyper@alumni.caltech.edu> - 2023-09-22 11:39 -0400
    Re: Call to a function Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-22 16:47 +0000
      Re: Call to a function James Kuyper <jameskuyper@alumni.caltech.edu> - 2023-09-23 01:26 -0400
      Re: Call to a function Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-23 07:38 -0700
  Re: Call to a function Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-09-22 11:54 -0700
    Re: Call to a function Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-10-03 06:34 -0700
      Re: Call to a function Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-10-03 15:13 -0700
        Re: Call to a function Kaz Kylheku <864-117-4973@kylheku.com> - 2023-10-04 01:52 +0000
          Re: Call to a function Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-10-03 19:13 -0700
        Re: Call to a function "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2023-10-03 20:41 -0700

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