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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Abstract Syntax Tree for C programs
Date: Fri, 07 Jun 2019 10:56:06 -0700
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Bart <bc@freeuk.com> writes:
> On 07/06/2019 17:42, Ben Bacarisse wrote:
[...]
>> Not function pointers.
>
> Why not? They seem to work:
>
>    C:\c>type c.c
>        #include <stdio.h>
>
>        typedef struct {int d,m,y[100];} date;
>
>        int main(void) {
>            date d;
>            printf("%p %p %p %p %p %p\n",d,d,d, main,main,main);
>        }
>
>    C:\c>gcc -std=c11 -pedantic-errors c.c

That code has undefined behavior, but it doesn't violate a constraint
or syntax error, so the language doesn't require a diagnostic.
Recent versions of gcc (4.8 and later, of the versions available
to me) do produce warnings.

Did your gcc print any warnings?

Incidentally, on my system the last three printed values are not
the same.  This is an unsurprising result of undefined behavior.

[...]

> But how would your officially print the value of a function pointer? 

There is no portable way to print a function pointer value.  Casting
to void* and using "%p" is likely to "work", but the cast itself is
problematic at best.  Or you could access a function pointer object
as as array of unsigned char and print its representation.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */