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/* Return a NULL pointer, without letting the compiler know it.
Copyright (C) 2017 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <stdlib.h>
/* Return NULL.
Usual compilers are not able to infer something about the return value. */
static void *
null_ptr (void)
{
unsigned int x = rand ();
unsigned int y = x * x;
if (y & 2)
return (void *) -1;
else
return (void *) 0;
}
/* If you want to know why this always returns NULL, read
https://en.wikipedia.org/wiki/Quadratic_residue#Prime_power_modulus . */
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