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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Abstract Syntax Tree for C programs
Date: Wed, 05 Jun 2019 19:06:40 -0700
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James Kuyper <jameskuyper@alumni.caltech.edu> writes:
> On 6/5/19 7:09 PM, Keith Thompson wrote:
> ...
>> rule).  But if you're writing code that depends on POSIX features,
>> you're probably not going to use "-std=c11 -pedantic".
>
> But you might use
>
>     -std=c11 -pedantic -D_POSIX_C_SOURCE=200809L

I still get the warning, and using "-std=gnu11" doesn't turn it off:

$ cat c.c
#include <dlfcn.h>
int main(void) {
    int (*ptr)(void) = (int(*)(void))dlsym((void*)0, "foo");
}
$ gcc -std=c11 -pedantic -D_POSIX_C_SOURCE=200809L c.c -ldl -o c
c.c: In function ‘main’:
c.c:3:24: warning: ISO C forbids conversion of object pointer to function pointer type [-Wpedantic]
     int (*ptr)(void) = (int(*)(void))dlsym((void*)0, "foo");
                        ^
$ 

(dlsym() isn't going to returning anything meaningful with those
arguments; the point is the compile-time diagnostics.)

-- 
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 */