1 files changed, 33 insertions, 0 deletions
diff --git a/gnulib-tests/null-ptr.h b/gnulib-tests/null-ptr.h
new file mode 100644
index 0000000..b978418
--- /dev/null
+++ b/gnulib-tests/null-ptr.h
@@ -0,0 +1,33 @@
+/* Return a NULL pointer, without letting the compiler know it.
+   Copyright (C) 2017-2020 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 <https://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 .  */